CLASS 8 PHYSICS : Household Electricity
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Questions and Answers

What is the primary function of a fuse wire in a household circuit?

  • To increase the current flow in the circuit.
  • To protect the circuit and appliances from damage due to excessive current. (correct)
  • To prevent the circuit from overheating.
  • To regulate the voltage in the circuit.

    • Why does a fuse wire have a low melting point?

  • To allow for easy replacement of the fuse wire.
  • To prevent the circuit from becoming too hot.
  • To provide a path for excess current to flow.
  • To ensure that it melts quickly when the circuit is overloaded. (correct)

    • Where is a switch typically connected in a household circuit?

  • Between the neutral wire and the appliance.
  • Between the earth wire and the appliance.
  • Between the live wire and the appliance. (correct)
  • Directly to the appliance.

    • What is the purpose of connecting two light bulbs in parallel in a household circuit?

    <p>To allow one bulb to continue glowing even if the other bulb is fused. (C)</p> Signup and view all the answers

    What is the unit used to measure electrical energy consumption in a household?

    <p>Kilowatt-hour (kWh) (D)</p> Signup and view all the answers

    Where is an electric meter typically located in a house?

    <p>On the front or outside wall of the house. (B)</p> Signup and view all the answers

    Which of the following is an advantage of using an M.C.B. over a fuse wire?

    <p>M.C.B.s can be easily reset after tripping. (C)</p> Signup and view all the answers

    Which of the following conditions usually causes a fuse wire to melt?

    <p>When the current flow in the circuit exceeds a safe limit. (D)</p> Signup and view all the answers

    What happens when a positively charged glass rod is brought near a metal rod?

    <p>Electrons in the metal rod are attracted to the near end, making that end negatively charged. (A)</p> Signup and view all the answers

    What is the purpose of the tin foil on the sides of the glass bottle in a gold leaf electroscope?

    <p>To provide a path for the charge to escape to the ground. (A)</p> Signup and view all the answers

    How can you determine if a charged body is positively or negatively charged using a charged pith ball electroscope?

    <p>If the pith ball moves away from the body, the body is positively charged. (C)</p> Signup and view all the answers

    What happens to the leaves of a gold leaf electroscope when a positively charged body touches its brass disc?

    <p>The leaves diverge. (C)</p> Signup and view all the answers

    How does a lightning conductor protect a building from lightning strikes?

    <p>It attracts the lightning strike and directs it to the ground. (D)</p> Signup and view all the answers

    What happens during a thunderstorm when a charged cloud passes over the earth?

    <p>The earth becomes negatively charged by induction. (B)</p> Signup and view all the answers

    What is the main principle behind charging by induction?

    <p>Separation of charges. (A)</p> Signup and view all the answers

    Why is it dangerous to stand under a tree during a thunderstorm?

    <p>All of the above. (D)</p> Signup and view all the answers

    What is the purpose of the copper plate buried deep into the ground in a lightning conductor?

    <p>To provide a path for the lightning charge to flow into the ground. (B)</p> Signup and view all the answers

    What is the best safety measure to take during a thunderstorm?

    <p>All of the above. (D)</p> Signup and view all the answers

    What is the main purpose of an earth wire in an electrical appliance?

    <p>To provide a safe path for current to flow to the ground in case of a short circuit. (B)</p> Signup and view all the answers

    Which of the following statements is TRUE about parallel arrangement in a household circuit?

    <p>Each appliance has its own independent path for current flow. (A)</p> Signup and view all the answers

    What is the purpose of an MCB in a household circuit?

    <p>To prevent the circuit from overheating. (A)</p> Signup and view all the answers

    Which of the following is NOT a reason for a short circuit?

    <p>Properly functioning circuit breakers tripping due to overload. (D)</p> Signup and view all the answers

    What happens to a glass rod when it's rubbed with silk?

    <p>It loses electrons and becomes positively charged. (A)</p> Signup and view all the answers

    What is the principle of conservation of charges?

    <p>The total charge of an isolated system remains constant. (C)</p> Signup and view all the answers

    What type of charge does an ebonite rod acquire after being rubbed with fur?

    <p>Negative charge (D)</p> Signup and view all the answers

    Why do two ebonite rods rubbed with fur repel each other?

    <p>Because they have the same charge. (C)</p> Signup and view all the answers

    What does it mean for an object to be electrically neutral?

    <p>It has an equal number of protons and electrons. (C)</p> Signup and view all the answers

    What is the main difference between a conductor and an insulator in terms of electrical conductivity?

    <p>Conductors have a higher concentration of free electrons than insulators. (D)</p> Signup and view all the answers

    Which of the following materials is NOT a good conductor of electricity?

    <p>Rubber (D)</p> Signup and view all the answers

    What is charging by conduction?

    <p>Charging an object by direct contact with a charged object. (D)</p> Signup and view all the answers

    When is a conductor positively charged by conduction?

    <p>When it touches a positively charged object. (C)</p> Signup and view all the answers

    What is the main difference between a fuse wire and an MCB in terms of their operation?

    <p>Fuses need to be replaced after tripping, while MCBs can be reset. (C)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of a good conductor?

    <p>Ability to be charged by rubbing. (C)</p> Signup and view all the answers

    Why is it important to earth electrical appliances?

    <p>To provide a safe path for current to the ground if a live wire comes into contact with the appliance's metal casing. (A)</p> Signup and view all the answers

    What is the main function of a fuse wire in a circuit?

    <p>To prevent the circuit from overheating. (C)</p> Signup and view all the answers

    Which of these is NOT a reason why an MCB is superior to a fuse wire?

    <p>MCBs have a higher current capacity than fuse wires. (D)</p> Signup and view all the answers

    What is the main purpose of connecting appliances in parallel in a household circuit?

    <p>To ensure that all appliances receive the same voltage. (D)</p> Signup and view all the answers

    Which of the following components is typically connected AFTER the company fuse in a household electrical circuit?

    <p>The electric meter. (B)</p> Signup and view all the answers

    What is the relationship between the thickness of a fuse wire and its current rating?

    <p>Thicker fuse wires have higher current ratings. (A)</p> Signup and view all the answers

    What is the primary function of an earth wire in an electrical appliance?

    <p>To provide a safe path for current to flow to the ground in case of a fault. (C)</p> Signup and view all the answers

    When a positively charged glass rod is brought near a metal rod, what happens to the free electrons in the metal rod?

    <p>The free electrons move towards the glass rod, making the end near the glass rod negatively charged. (D)</p> Signup and view all the answers

    What is the primary function of a lightning conductor?

    <p>To provide a path for the lightning strike to pass safely to the ground. (D)</p> Signup and view all the answers

    Which of the following is NOT a safety measure to observe during a thunderstorm?

    <p>Using the wired phone during a thunderstorm. (D)</p> Signup and view all the answers

    A negatively charged gold leaf electroscope is touched with a charged body. The leaves of the electroscope diverge further. What can you conclude about the charge of the body?

    <p>The body is negatively charged. (B)</p> Signup and view all the answers

    Two similarly charged pith balls are suspended from a common point. What will happen to the pith balls when they are brought close to each other?

    <p>They will repel each other. (B)</p> Signup and view all the answers

    How does the charge on a glass rod change when rubbed with silk?

    <p>It loses electrons. (C)</p> Signup and view all the answers

    Which of the following statements accurately describes the interaction between a positively charged object and a negatively charged object?

    <p>They attract each other because they have opposite charges. (C)</p> Signup and view all the answers

    In a household circuit, why is a parallel arrangement preferred over a series arrangement?

    <p>In a parallel arrangement, if one appliance fails, the others continue to work. (D)</p> Signup and view all the answers

    Which of the following best describes the function of an Earth wire in an electrical appliance?

    <p>To provide a safe path for current to flow to the ground in case of a short circuit. (A)</p> Signup and view all the answers

    What happens when two objects are rubbed together?

    <p>One object gains electrons while the other loses electrons. (D)</p> Signup and view all the answers

    Which of the following statements is TRUE about the conservation of charges?

    <p>Charge can be transferred from one object to another but the total amount remains constant. (C)</p> Signup and view all the answers

    What is the main difference between a conductor and an insulator?

    <p>Conductors allow electricity to flow through them easily, while insulators do not. (A)</p> Signup and view all the answers

    What is the key difference between an MCB and a fuse wire?

    <p>An MCB can be reset after tripping, while a fuse wire needs to be replaced. (D)</p> Signup and view all the answers

    In the context of charging a conductor by conduction, what is the main requirement for the conductor to be charged?

    <p>The conductor must be in direct contact with the charged object. (C)</p> Signup and view all the answers

    Which of these is NOT a common cause of a short circuit in a household electrical system?

    <p>Connecting appliances in parallel arrangement. (D)</p> Signup and view all the answers

    Which of the following statements best describes how a glass rod becomes positively charged when rubbed with silk?

    <p>The glass rod loses electrons to the silk. (B)</p> Signup and view all the answers

    What happens to the free electrons in an ebonite rod when it is rubbed with fur?

    <p>Electrons move from the fur to the ebonite rod. (A)</p> Signup and view all the answers

    Which of the following is TRUE about an atom in its electrically neutral state?

    <p>The number of protons is equal to the number of electrons. (B)</p> Signup and view all the answers

    Why is it NOT advisable to stand under a tree during a thunderstorm?

    <p>Trees are good conductors of electricity and can attract lightning strikes. (D)</p> Signup and view all the answers

    Why is a 15 A fuse wire thicker than a 5 A fuse wire?

    <p>A thicker wire can handle more current before reaching its melting point, thus requiring a higher rating. (C)</p> Signup and view all the answers

    In a household circuit, why is an M.C.B. considered superior to a fuse wire?

    <p>An M.C.B. is a safer alternative because it can interrupt the flow of current much faster than a fuse wire in case of a short circuit. (B)</p> Signup and view all the answers

    A fuse wire melts when a large current passes through it. What happens to the electricity flow in the circuit when the fuse wire melts?

    <p>The fuse wire creates a break in the circuit, preventing the flow of current. (A)</p> Signup and view all the answers

    Why is connecting an electric meter after the company fuse in a household electrical circuit a safety precaution?

    <p>It protects the meter from damage caused by high currents or short circuits. (D)</p> Signup and view all the answers

    What is the main principle behind the operation of a fuse wire?

    <p>Fuse wires operate based on the principle of Joule's heating effect, where the heat generated by the current flow melts the fuse wire. (D)</p> Signup and view all the answers

    If a fuse wire is rated at 5 A, what does it mean?

    <p>The fuse wire will only melt if the current exceeds 5 A. (B)</p> Signup and view all the answers

    In what way is an M.C.B. similar to a fuse wire?

    <p>Both have the same function of protecting appliances from damage by interrupting the flow of current in case of an overload or short circuit. (D)</p> Signup and view all the answers

    A glass rod B is positively charged and touched with a metal rod A. Which statement accurately describes the charge transfer and the resulting charge on the rods?

    <p>Electrons move from rod A to rod B; rod A becomes positively charged and rod B becomes negatively charged. (D)</p> Signup and view all the answers

    A negatively charged gold leaf electroscope is touched with a charged body, and the leaves diverge further. What is the nature of the charge on the body?

    <p>Positive (A)</p> Signup and view all the answers

    A positively charged glass rod is brought near one end of an uncharged metal rod. What happens to the free electrons in the metal rod?

    <p>The free electrons are attracted to the positively charged glass rod and accumulate at the end of the metal rod closest to the glass rod. (B)</p> Signup and view all the answers

    Which of the following situations would NOT cause the leaves of a gold leaf electroscope to diverge?

    <p>Touching the brass disc of an uncharged electroscope with a neutral object. (B)</p> Signup and view all the answers

    During a thunderstorm, a charged cloud passes over a tall building. Which of the following statements accurately describes the induced charge on the lightning conductor?

    <p>The spikes of the lightning conductor acquire the opposite charge as the cloud, providing a safe path for the charge to flow to the ground. (C)</p> Signup and view all the answers

    Which of the following statements accurately describes the function of the copper plate buried deep into the ground in a lightning conductor?

    <p>It provides a conductive path for the electrical charge to safely flow to the ground, preventing the lightning strike from damaging the building. (D)</p> Signup and view all the answers

    What is the primary function of an electroscope?

    <p>To detect the presence and nature of charge on a body. (C)</p> Signup and view all the answers

    When a glass rod rubbed with silk is brought near a negatively charged ebonite rod, what happens?

    <p>Both attract each other. (B)</p> Signup and view all the answers

    Two identical metal spheres, A and B, are mounted on insulating stands. Sphere A is given a positive charge and Sphere B is given a negative charge. If the two spheres are brought into contact, what happens to the charges on them?

    <p>The charges redistribute, resulting in both spheres having a smaller positive charge. (A)</p> Signup and view all the answers

    If a negatively charged ebonite rod is brought near a positively charged glass rod, what will happen?

    <p>The ebonite rod will be attracted towards the glass rod. (D)</p> Signup and view all the answers

    A positively charged object is brought close to a neutral metal sphere. What happens to the free electrons in the metal sphere?

    <p>They are attracted to the charged object, accumulating on the side closest to the object. (C)</p> Signup and view all the answers

    Why does a fuse wire melt when excessive current flows through it?

    <p>The heat generated by the high current melts the fuse wire. (D)</p> Signup and view all the answers

    If a circuit has a 15-ampere fuse wire and an appliance draws 20 amperes of current, what will happen?

    <p>The fuse wire will melt and break the circuit. (C)</p> Signup and view all the answers

    Which of these is a property of a good insulator?

    <p>It has a very high resistance to the flow of electricity. (A)</p> Signup and view all the answers

    Which of the following is NOT considered an advantage of using an MCB over a fuse wire?

    <p>MCBs are more expensive than fuse wires. (B)</p> Signup and view all the answers

    In a parallel arrangement of electrical appliances in a household circuit, what happens if one appliance stops working?

    <p>The other appliances in the circuit continue to work independently. (B)</p> Signup and view all the answers

    What is the main purpose of a lightning conductor?

    <p>To channel lightning strikes to the ground, preventing damage to the building. (A)</p> Signup and view all the answers

    If you were to rub a plastic comb with a wool cloth, what type of charge would the comb acquire?

    <p>It will gain a negative charge. (A)</p> Signup and view all the answers

    During charging by induction, what is the primary difference between the charging body and the object being charged?

    <p>The charging body does not physically touch the object being charged. (B)</p> Signup and view all the answers

    Which statement correctly describes the charging mechanism of an ebonite rod rubbed with fur?

    <p>Electrons move from the fur to the ebonite rod, making the rod negatively charged. (C)</p> Signup and view all the answers

    A positively charged object is brought near a neutral metal sphere. What happens to the charges within the metal sphere?

    <p>The positive charges in the sphere move away from the charged object, while the negative charges move towards it. (C)</p> Signup and view all the answers

    A fuse wire should have a high melting point.

    <p>False (B)</p> Signup and view all the answers

    When a switch is turned off, it disconnects the neutral wire.

    <p>False (B)</p> Signup and view all the answers

    In a parallel connection, if one bulb is fused, the other bulb will not glow.

    <p>False (B)</p> Signup and view all the answers

    All household electrical appliances are connected in series.

    <p>False (B)</p> Signup and view all the answers

    An electric meter measures the amount of electric power consumed.

    <p>False (B)</p> Signup and view all the answers

    An electric fuse is a safety device that limits the current in an electric circuit.

    <p>True (A)</p> Signup and view all the answers

    A 50 A fuse wire is thinner than a 10 A fuse wire.

    <p>False (B)</p> Signup and view all the answers

    An M.C.B. is a mechanical device that automatically disconnects the circuit.

    <p>True (A)</p> Signup and view all the answers

    A positively charged glass rod will attract a negatively charged pith ball.

    <p>True (A)</p> Signup and view all the answers

    The leaves of a gold leaf electroscope diverge when a positively charged body touches its brass disc.

    <p>True (A)</p> Signup and view all the answers

    If the divergence of the leaves of a positively charged gold leaf electroscope decreases when a charged body is brought near, the body is positively charged.

    <p>False (B)</p> Signup and view all the answers

    Lightning is a spark that occurs between two clouds of opposite charge.

    <p>True (A)</p> Signup and view all the answers

    A lightning conductor is a device used to attract lightning strikes to a building.

    <p>False (B)</p> Signup and view all the answers

    During a thunderstorm, it is safe to stand under a tree.

    <p>False (B)</p> Signup and view all the answers

    The copper rod in a lightning conductor is connected to a copper plate buried deep into the ground.

    <p>True (A)</p> Signup and view all the answers

    The safety measure of removing plugs from appliances and not using wired phones during a thunderstorm is to prevent electrocution from lightning.

    <p>True (A)</p> Signup and view all the answers

    Charging by induction requires direct contact between the charged object and the object being charged.

    <p>False (B)</p> Signup and view all the answers

    A positively charged glass rod will attract a negatively charged glass rod.

    <p>False (B)</p> Signup and view all the answers

    A Miniature Circuit Breaker (MCB) can be reset after it trips, while a fuse wire must be replaced.

    <p>True (A)</p> Signup and view all the answers

    Circuit breakers are preferred over fuse wires in household circuits.

    <p>True (A)</p> Signup and view all the answers

    An MCB typically takes a longer time to interrupt a circuit than a fuse wire.

    <p>False (B)</p> Signup and view all the answers

    An appliance will stop working if its live wire comes into contact with its neutral wire.

    <p>True (A)</p> Signup and view all the answers

    If one bulb in a parallel circuit is fused, all other bulbs in the circuit will also stop working.

    <p>False (B)</p> Signup and view all the answers

    The earth wire is typically colored red or brown.

    <p>False (B)</p> Signup and view all the answers

    The metal casing of an electrical appliance is connected to the neutral wire for safety.

    <p>False (B)</p> Signup and view all the answers

    When two objects are rubbed together, both objects gain the same type of charge - either both positive or both negative.

    <p>False (B)</p> Signup and view all the answers

    Electricity at rest refers to the continuous flow of electrons through a conductor.

    <p>False (B)</p> Signup and view all the answers

    When a glass rod is rubbed with silk, the glass rod becomes negatively charged.

    <p>False (B)</p> Signup and view all the answers

    An ebonite rod rubbed with fur acquires a positive charge.

    <p>False (B)</p> Signup and view all the answers

    Two ebonite rods rubbed with fur will repel each other.

    <p>True (A)</p> Signup and view all the answers

    The total charge of a system before and after rubbing remains the same.

    <p>True (A)</p> Signup and view all the answers

    An atom is electrically neutral because it has equal numbers of protons and neutrons.

    <p>False (B)</p> Signup and view all the answers

    A substance with a large number of free electrons is considered an insulator.

    <p>False (B)</p> Signup and view all the answers

    A fuse wire with a higher current rating is generally thinner than one with a lower current rating.

    <p>False (B)</p> Signup and view all the answers

    In a household circuit, appliances are typically connected in a series arrangement.

    <p>False (B)</p> Signup and view all the answers

    An electric meter measures the amount of electric power consumed by a household.

    <p>False (B)</p> Signup and view all the answers

    The electric meter in a house is typically connected before the company fuse.

    <p>False (B)</p> Signup and view all the answers

    When a switch is turned off, it disconnects the neutral wire in a household circuit.

    <p>False (B)</p> Signup and view all the answers

    A miniature circuit breaker (MCB) is a safer alternative to a fuse wire because it can be reset after a short circuit.

    <p>True (A)</p> Signup and view all the answers

    A fuse wire with a low melting point is more likely to melt when a large current flows through it.

    <p>True (A)</p> Signup and view all the answers

    The primary function of a fuse wire is to protect the electrical appliances from damage caused by high voltage fluctuations.

    <p>False (B)</p> Signup and view all the answers

    When a positively charged glass rod is brought near the end of an uncharged metal rod, the end of the metal rod closest to the glass rod becomes positively charged.

    <p>False (B)</p> Signup and view all the answers

    Touching a negatively charged electroscope with a negatively charged object will cause the leaves to diverge further.

    <p>True (A)</p> Signup and view all the answers

    During charging by induction, the object being charged gains electrons from the charging object.

    <p>False (B)</p> Signup and view all the answers

    A lightning conductor prevents lightning strikes from occurring entirely.

    <p>False (B)</p> Signup and view all the answers

    A pith ball electroscope can be used to determine the type of charge on an object by observing whether the pith ball moves towards or away from the object.

    <p>True (A)</p> Signup and view all the answers

    The leaves of a gold leaf electroscope diverge because like charges repel each other.

    <p>True (A)</p> Signup and view all the answers

    Standing close to a tall tree during a thunderstorm is a safe practice because trees are good conductors of electricity.

    <p>False (B)</p> Signup and view all the answers

    The copper plate buried deep into the ground in a lightning conductor is necessary to prevent the lightning strike from damaging the building.

    <p>True (A)</p> Signup and view all the answers

    A lightning conductor works on the principle of attraction between opposite charges.

    <p>False (B)</p> Signup and view all the answers

    To protect a building from lightning strikes, the lightning conductor should be made of a material that is a good insulator.

    <p>False (B)</p> Signup and view all the answers

    The switch in a household circuit is usually connected in series with the appliance.

    <p>True (A)</p> Signup and view all the answers

    An M.C.B. is designed to handle higher currents compared to a fuse wire.

    <p>False (B)</p> Signup and view all the answers

    A short circuit occurs when the live wire touches the neutral wire.

    <p>True (A)</p> Signup and view all the answers

    The earth wire is connected to the metal casing of an electrical appliance to prevent electric shocks.

    <p>True (A)</p> Signup and view all the answers

    When a glass rod is rubbed with silk, the glass rod acquires a negative charge.

    <p>False (B)</p> Signup and view all the answers

    The fur becomes negatively charged after being rubbed with an ebonite rod.

    <p>False (B)</p> Signup and view all the answers

    Two like charges attract each other.

    <p>False (B)</p> Signup and view all the answers

    The total charge of a system remains unchanged before and after rubbing two objects together.

    <p>True (A)</p> Signup and view all the answers

    The protons in an atom are negatively charged.

    <p>False (B)</p> Signup and view all the answers

    An atom is always electrically neutral.

    <p>True (A)</p> Signup and view all the answers

    In charging by induction, the object to be charged is touched by a charged body.

    <p>False (B)</p> Signup and view all the answers

    Metals are considered good insulators of electricity.

    <p>False (B)</p> Signup and view all the answers

    A fuse wire can be reset after it has been triggered (blown).

    <p>False (B)</p> Signup and view all the answers

    Conductors have very few or no free electrons.

    <p>False (B)</p> Signup and view all the answers

    When a negatively charged object is brought near a neutral object, the neutral object will be attracted to the negatively charged object.

    <p>True (A)</p> Signup and view all the answers

    A fuse wire with a higher current rating will be thinner than a fuse wire with a lower current rating.

    <p>False (B)</p> Signup and view all the answers

    The counter on an electric meter measures the number of rotations of the armature in a specific time period.

    <p>True (A)</p> Signup and view all the answers

    An electric fuse is a device that limits the voltage in an electric circuit, preventing excessive voltage from damaging appliances.

    <p>False (B)</p> Signup and view all the answers

    A 10 A fuse will melt before a 5 A fuse when the same excessive current flows through both.

    <p>False (B)</p> Signup and view all the answers

    The electric meter is typically connected before the company fuse in a household electrical circuit.

    <p>False (B)</p> Signup and view all the answers

    The full form of MCB is Miniature Circuit Breaker.

    <p>True (A)</p> Signup and view all the answers

    A fuse wire melts and breaks the circuit when there's a short circuit or a sudden increase in voltage.

    <p>True (A)</p> Signup and view all the answers

    Parallel connection in a household circuit ensures that all appliances receive the same voltage, unlike series connection, where voltage is divided between appliances.

    <p>True (A)</p> Signup and view all the answers

    A fuse wire is designed to break a circuit much faster than an MCB.

    <p>False (B)</p> Signup and view all the answers

    A parallel circuit in a household allows all appliances to operate at the same voltage.

    <p>True (A)</p> Signup and view all the answers

    A $100 \Omega$ resistor connected to a $12V$ power supply will draw more current than a $50 \Omega$ resistor connected to the same power supply.

    <p>False (B)</p> Signup and view all the answers

    An ebonite rod acquires a positive charge when rubbed with fur.

    <p>False (B)</p> Signup and view all the answers

    A glass rod rubbed with silk will repel another glass rod that has been rubbed with silk.

    <p>True (A)</p> Signup and view all the answers

    The earth wire is connected to the metal casing of an electrical appliance to prevent a short circuit.

    <p>False (B)</p> Signup and view all the answers

    A neutral wire has a higher voltage than a live wire.

    <p>False (B)</p> Signup and view all the answers

    A conductor is a material that allows electricity to flow through it easily.

    <p>True (A)</p> Signup and view all the answers

    In charging by conduction, the object being charged always obtains the opposite charge of the charging body.

    <p>False (B)</p> Signup and view all the answers

    The total charge of a system before and after rubbing remains the same, illustrating the conservation of charges.

    <p>True (A)</p> Signup and view all the answers

    The nucleus of an atom is negatively charged.

    <p>False (B)</p> Signup and view all the answers

    A negatively charged body will attract a positively charged body.

    <p>True (A)</p> Signup and view all the answers

    A material with a high resistance is a good conductor.

    <p>False (B)</p> Signup and view all the answers

    An atom is electrically neutral because it has an equal number of protons and electrons.

    <p>True (A)</p> Signup and view all the answers

    A fuse wire is designed to melt and break the circuit before excessive current causes damage.

    <p>True (A)</p> Signup and view all the answers

    A positively charged glass rod has an excess of electrons.

    <p>False (B)</p> Signup and view all the answers

    When the gold leaf electroscope is positively charged and touched with a positively charged body, the leaves diverge further.

    <p>True (A)</p> Signup and view all the answers

    During charging by induction, the far end of a metal rod acquires a negative charge when a positively charged object is brought near.

    <p>True (A)</p> Signup and view all the answers

    The lightning conductor protects buildings by drawing lightning towards itself.

    <p>False (B)</p> Signup and view all the answers

    The two types of electroscopes include the gold leaf electroscope and the copper leaf electroscope.

    <p>False (B)</p> Signup and view all the answers

    When touching the end of a negatively charged rod to the earth, free electrons move into the rod.

    <p>False (B)</p> Signup and view all the answers

    A common safety measure during a thunderstorm includes the use of wired phones.

    <p>False (B)</p> Signup and view all the answers

    Induction charging occurs when a charged object touches a neutral object.

    <p>False (B)</p> Signup and view all the answers

    The divergence of leaves in a gold leaf electroscope indicates the presence of charge only if they move towards each other.

    <p>False (B)</p> Signup and view all the answers

    The principle of induction is utilized in both electroscopes and lightning conductors.

    <p>True (A)</p> Signup and view all the answers

    A ______ wire has a low melting point to protect appliances from damage.

    <p>fuse</p> Signup and view all the answers

    When a switch is turned off, it disconnects the ______ wire.

    <p>live</p> Signup and view all the answers

    Household appliances are usually connected in a ______ connection.

    <p>parallel</p> Signup and view all the answers

    An electric meter measures the amount of electrical energy used, measured in ______.

    <p>kWh</p> Signup and view all the answers

    The electric meter is connected ______ the company fuse.

    <p>after</p> Signup and view all the answers

    Electrical energy is often measured in ______ units.

    <p>BOT</p> Signup and view all the answers

    The full form of M.C.B. is ______.

    <p>miniature circuit breaker</p> Signup and view all the answers

    A thicker fuse wire is used for a ______ current rating.

    <p>higher</p> Signup and view all the answers

    A positively charged glass rod has a ______ of electrons.

    <p>deficiency</p> Signup and view all the answers

    In charging by induction, a ______ charged glass rod is brought near a metal rod.

    <p>positively</p> Signup and view all the answers

    The near end of the metal rod acquires a ______ charge in charging by induction.

    <p>negative</p> Signup and view all the answers

    An ______ is a device used to detect the presence and nature of charge on a body.

    <p>electroscope</p> Signup and view all the answers

    If a charged pith ball moves away from a charged body, the body has a ______ charge.

    <p>positive</p> Signup and view all the answers

    The gold leaf electroscope has two gold or aluminium leaves hanging from a ______ rod.

    <p>brass</p> Signup and view all the answers

    When a positively charged glass rod is touched with the disc of an uncharged gold leaf electroscope, the leaves ______ .

    <p>diverge</p> Signup and view all the answers

    During a thunderstorm, when a charged cloud passes over the earth, it acquires an ______ charge by induction.

    <p>opposite</p> Signup and view all the answers

    Lightning is a spark that occurs between two ______ charged clouds or a charged cloud and the earth.

    <p>oppositely</p> Signup and view all the answers

    A lightning conductor is a device used to prevent a building from being damaged by ______ .

    <p>lightning</p> Signup and view all the answers

    A ______ circuit breaker (MCB) is a safety device that automatically interrupts the flow of electricity in a circuit when a fault occurs.

    <p>miniature</p> Signup and view all the answers

    A ______ wire melts and breaks the circuit when the current flowing through it exceeds a certain limit.

    <p>fuse</p> Signup and view all the answers

    The ______ wire in a cable is usually red or brown and carries the electrical current.

    <p>live</p> Signup and view all the answers

    The ______ wire in a cable is usually black or light blue and completes the electrical circuit by returning the current to the source.

    <p>neutral</p> Signup and view all the answers

    The ______ wire in a cable is usually green or yellow and provides a path for current to flow to the ground in case of a fault.

    <p>earth</p> Signup and view all the answers

    A ______ circuit is one in which the electrical appliances are connected in such a way that each appliance has its own independent path for the current to flow.

    <p>parallel</p> Signup and view all the answers

    When two objects are rubbed together, ______ are transferred from one object to the other.

    <p>electrons</p> Signup and view all the answers

    The ______ of an atom is positively charged due to the presence of protons.

    <p>nucleus</p> Signup and view all the answers

    Substances that have a large number of free electrons are called ______.

    <p>conductors</p> Signup and view all the answers

    Substances that have very few or no free electrons are called ______.

    <p>insulators</p> Signup and view all the answers

    The process of charging a conductor by touching it with a charged body is called charging by ______.

    <p>conduction</p> Signup and view all the answers

    The principle that states that the total charge of a system remains constant in an isolated system is called the conservation of ______.

    <p>charges</p> Signup and view all the answers

    An ebonite rod acquires a ______ charge when rubbed with fur because free electrons move from the fur to the rod.

    <p>negative</p> Signup and view all the answers

    Two ebonite rods rubbed with fur will ______ each other because they both acquire a negative charge.

    <p>repel</p> Signup and view all the answers

    An atom is considered ______ when the number of protons is equal to the number of electrons.

    <p>neutral</p> Signup and view all the answers

    A fuse wire should have a low ______ point so that when a large amount of current passes through it, the wire will melt and does not allow excess current to pass thus protecting the appliance or circuit from getting damaged.

    <p>melting</p> Signup and view all the answers

    When the switch of an electrical appliance is put off, it disconnects the ______ wire because the switch is connected in the live wire.

    <p>live</p> Signup and view all the answers

    The two bulbs are connected in a ______ connection so that if one bulb gets fused the other will glow without being affected.

    <p>parallel</p> Signup and view all the answers

    In household electrical circuits, all appliances are connected in a ______ connection.

    <p>parallel</p> Signup and view all the answers

    An electric meter measures the amount of electric ______ consumed by the consumer in the unit kWh for which the electricity bill is paid by him to the electricity board.

    <p>energy</p> Signup and view all the answers

    Electric meter is connected after the company ______ to the electric cable coming from the pole to the house.

    <p>fuse</p> Signup and view all the answers

    The purpose of kWh meter is to measure the amount of electric ______ consumed by the consumer in kWh for which the electricity bill is paid by him to the electricity board.

    <p>energy</p> Signup and view all the answers

    Electrical energy is generally measured in a unit called B.O.T (Board of Trade) unit or ______ (kilowatt hour) for which the electricity bill is paid.

    <p>kWh</p> Signup and view all the answers

    A ______ rod is positively charged due to a deficiency of electrons.

    <p>glass</p> Signup and view all the answers

    When a positively charged glass rod is brought near a metal rod, the end of the metal rod closest to the glass rod acquires a ______ charge.

    <p>negative</p> Signup and view all the answers

    In charging by ______, a charged object is brought near an uncharged object, causing a separation of charges within the uncharged object.

    <p>induction</p> Signup and view all the answers

    The two main types of electroscopes are the pith ball electroscope and the ______ electroscope.

    <p>gold leaf</p> Signup and view all the answers

    A charged pith ball will move ______ from a body with the same type of charge and ______ towards a body with the opposite type of charge.

    <p>away, towards</p> Signup and view all the answers

    In a gold leaf electroscope, the leaves diverge when a charged object is brought in contact with the brass disc due to the ______ of like charges.

    <p>repulsion</p> Signup and view all the answers

    A negatively charged body brought near a positively charged gold leaf electroscope will cause the leaves to ______ their divergence.

    <p>decrease</p> Signup and view all the answers

    The spark that occurs between oppositely charged clouds or between a charged cloud and the earth is known as ______.

    <p>lightning</p> Signup and view all the answers

    A ______ conductor is a device used to protect buildings from lightning damage.

    <p>lightning</p> Signup and view all the answers

    A ______ is a safety device that automatically switches off the circuit in a very short time.

    <p>miniature circuit breaker</p> Signup and view all the answers

    The ______ wire in a cable is typically red or brown.

    <p>live</p> Signup and view all the answers

    The metal covering of an electrical appliance is connected to the ______ wire to protect from electric shock.

    <p>earth</p> Signup and view all the answers

    When two objects are rubbed together, there is a transfer of ______ electrons.

    <p>free</p> Signup and view all the answers

    An atom is ______ neutral because the number of protons is equal to the number of electrons.

    <p>electrically</p> Signup and view all the answers

    The three main constituents of an atom are protons, neutrons, and ______.

    <p>electrons</p> Signup and view all the answers

    In charging by ______ method, the conductor to be charged is touched with a charged body.

    <p>conduction</p> Signup and view all the answers

    When a glass rod is rubbed with silk, the glass rod acquires a ______ charge.

    <p>positive</p> Signup and view all the answers

    The ______ of charges states that the total charge of a system remains constant before and after rubbing.

    <p>conservation</p> Signup and view all the answers

    Two ebonite rods rubbed with fur repel each other because they acquire the same ______ charge.

    <p>negative</p> Signup and view all the answers

    An MCB offers greater ______, flexibility, and safety compared to a fuse wire.

    <p>protection</p> Signup and view all the answers

    The ______ arrangement is generally preferred in a household circuit because each appliance works independently.

    <p>parallel</p> Signup and view all the answers

    A short circuit occurs when the ______ wire touches the neutral wire.

    <p>live</p> Signup and view all the answers

    When an ebonite rod is rubbed with fur, the ______ loses electrons and becomes positively charged.

    <p>fur</p> Signup and view all the answers

    A ______ wire should have a low melting point so that when a large amount of current passes through it, the wire will melt and does not allow excess current to pass thus protecting the appliance or circuit from getting damaged.

    <p>fuse</p> Signup and view all the answers

    The two bulbs are connected in ______ connection so that if one bulb gets fused other will glow without being affected.

    <p>parallel</p> Signup and view all the answers

    In ______ electrical circuits, all appliances are connected in parallel connection.

    <p>household</p> Signup and view all the answers

    If electricity is in use, the electric ______ flows which rotates the armature of the meter.

    <p>current</p> Signup and view all the answers

    A ______ is a device which is used to limit the current in an electric circuit.

    <p>fuse</p> Signup and view all the answers

    The full form of M.C.B. is ______ circuit breaker.

    <p>miniature</p> Signup and view all the answers

    An M.C.B. is ______ to the fuse wire in the following ways:

    <p>superior</p> Signup and view all the answers

    A ______ rod, when rubbed with silk, becomes positively charged.

    <p>glass</p> Signup and view all the answers

    The ______ of electrons from a metal rod to a positively charged glass rod results in the metal rod becoming positively charged.

    <p>loss</p> Signup and view all the answers

    Charging by ______ involves bringing a charged object near an uncharged object to induce a separation of charges.

    <p>induction</p> Signup and view all the answers

    A positively charged glass rod brought near a metal rod causes the near end of the metal rod to acquire a ______ charge.

    <p>negative</p> Signup and view all the answers

    An electroscope is a device used to detect the ______ and nature of a charge on a body.

    <p>presence</p> Signup and view all the answers

    The ______ ball electroscope is one type of electroscope, along with the gold leaf electroscope.

    <p>pith</p> Signup and view all the answers

    A positively charged pith ball electroscope will move ______ when a negatively charged body is brought near it.

    <p>towards</p> Signup and view all the answers

    A gold leaf electroscope consists of two ______ leaves hanging from a brass rod.

    <p>gold</p> Signup and view all the answers

    If the leaves of a gold leaf electroscope ______, it indicates the presence of a charge on the touched object.

    <p>diverge</p> Signup and view all the answers

    Lightning is a spark that occurs between oppositely charged ______ or between a charged cloud and the earth.

    <p>clouds</p> Signup and view all the answers

    An ______ circuit is created when the live wire touches the neutral wire.

    <p>short</p> Signup and view all the answers

    In a household circuit, appliances are typically connected in ______ to ensure independent operation.

    <p>parallel</p> Signup and view all the answers

    The ______ wire is usually green or yellow and is used to protect against electric shock.

    <p>earth</p> Signup and view all the answers

    When two objects are rubbed together, one loses electrons and becomes ______ charged, while the other gains electrons and becomes negatively charged.

    <p>positively</p> Signup and view all the answers

    The ______ is the positively charged center of an atom.

    <p>nucleus</p> Signup and view all the answers

    In charging by ______, a conductor is touched or brought in contact with a charged body.

    <p>conduction</p> Signup and view all the answers

    A ______ is an electrical device designed to protect circuits from overcurrents.

    <p>fuse</p> Signup and view all the answers

    An MCB is a ______ circuit breaker that can be reset after tripping.

    <p>miniature</p> Signup and view all the answers

    A ______ circuit occurs when there is a direct low-resistance path for current to flow, often bypassing the intended load.

    <p>short</p> Signup and view all the answers

    A glass rod rubbed with silk acquires a ______ charge.

    <p>positive</p> Signup and view all the answers

    The law of conservation of charges states that the total charge of an isolated system remains ______.

    <p>constant</p> Signup and view all the answers

    Two ebonite rods rubbed with fur will ______ each other.

    <p>repel</p> Signup and view all the answers

    Atoms are ______ neutral because they have an equal number of protons and electrons.

    <p>electrically</p> Signup and view all the answers

    Substances with a very low number of free electrons are called ______.

    <p>insulators</p> Signup and view all the answers

    Explain why a fuse wire is designed to have a low melting point.

    <p>A fuse wire has a low melting point so that it melts and breaks the circuit when an excessive current flows through it, preventing damage to appliances and circuits. This is a crucial safety feature.</p> Signup and view all the answers

    Describe the purpose of connecting electrical appliances in parallel in a household circuit.

    <p>Connecting appliances in parallel allows each appliance to operate independently. If one appliance fails, the others continue to function normally, ensuring continuous power supply to the whole house.</p> Signup and view all the answers

    What is the role of an electric meter in a household circuit?

    <p>An electric meter measures the amount of electrical energy consumed by the household, allowing for accurate billing by the electricity board.</p> Signup and view all the answers

    Explain the difference between a 15A fuse wire and a 5A fuse wire in terms of their thickness.

    <p>A 15A fuse wire is thicker than a 5A fuse wire. The thickness of a fuse wire is directly proportional to its current rating. A higher current rating requires a thicker wire to handle the increased current flow.</p> Signup and view all the answers

    List two advantages of an MCB over a fuse wire.

    <p>MCBs are reusable, unlike fuse wires which need to be replaced after they blow. MCBs also provide faster protection than fuse wires, reacting more quickly to overcurrents.</p> Signup and view all the answers

    What is the unit of measurement for electrical energy consumption in a household?

    <p>Electrical energy consumption in a household is measured in kilowatt-hours (kWh).</p> Signup and view all the answers

    What is the meaning of the abbreviation MCB?

    <p>MCB stands for Miniature Circuit Breaker.</p> Signup and view all the answers

    Explain the main difference between a fuse wire and a Miniature Circuit Breaker (MCB) in terms of their operation and how they protect circuits.

    <p>A fuse wire melts and breaks the circuit when there's excessive current, while an MCB uses a magnetic or thermal mechanism to trip and interrupt the circuit. MCBs can be reset after tripping, while fuse wires need replacement.</p> Signup and view all the answers

    What is a short circuit and how does it typically occur in a household wiring system?

    <p>A short circuit occurs when the live wire comes into contact with the neutral wire, often due to faulty insulation or a malfunctioning appliance, creating a low-resistance path for current to flow.</p> Signup and view all the answers

    Why is parallel arrangement preferred in a household circuit over a series arrangement?

    <p>Parallel arrangements allow each appliance to operate independently, so if one appliance malfunctions, it doesn't affect the operation of others. They also ensure that each appliance receives the same voltage.</p> Signup and view all the answers

    What are the three types of wires typically found in a cable, and what is their role in a household circuit?

    <p>The wires are live (red or brown), neutral (black or light blue), and earth (green or yellow). The live wire carries the electric current to the appliance. The neutral wire completes the circuit, allowing current to return to the source. The earth wire provides a low-resistance path for current to flow to the ground in case of a short circuit, protecting against electric shocks.</p> Signup and view all the answers

    Explain the purpose of grounding the metal covering of electrical appliances.

    <p>Grounding the metal cover of an appliance connects it to the earth wire. If a live wire touches the cover accidentally, the current flows to the ground, protecting the user from electric shocks.</p> Signup and view all the answers

    What happens when two objects are rubbed together in terms of charge transfer, and what is the principle involved?

    <p>Rubbing creates a transfer of electrons. One object loses electrons and becomes positively charged, while the other gains electrons and becomes negatively charged. This is based on the principle of conservation of charges, where the total charge remains constant during the rubbing process.</p> Signup and view all the answers

    Explain the difference between static electricity and current electricity.

    <p>Static electricity refers to stationary electric charges that are not moving, while current electricity involves the continuous flow of electric charges through a conductor.</p> Signup and view all the answers

    Describe the structure of an atom and how it relates to electrical neutrality.

    <p>An atom has a nucleus containing protons (positive charge) and neutrons (no charge) surrounded by negatively charged electrons in orbits. An atom is electrically neutral because the number of protons (positive charges) is equal to the number of electrons (negative charges).</p> Signup and view all the answers

    What is the difference between a conductor and an insulator in terms of their ability to conduct electricity, and provide examples of each.

    <p>Conductors have a large number of free electrons that can easily move and carry electric current, while insulators have very few or no free electrons, hindering the flow of electricity. Metals like copper and aluminum are conductors, while materials like wood, rubber, and glass are insulators.</p> Signup and view all the answers

    Describe the two methods of charging a conductor by conduction and by induction, and explain the key differences.

    <p>Charging by conduction involves direct physical contact with a charged object, transferring the same type of charge to the conductor. Charging by induction involves bringing a charged object near the conductor, inducing an opposite charge on the conductor without direct contact.</p> Signup and view all the answers

    What is the purpose of a lightning conductor and explain how it protects a building from lightning strikes?

    <p>A lightning conductor is a metal rod connected to a grounding wire, designed to attract lightning strikes. The pathway of least resistance for the lightning current is through the conductor and grounding wire, diverting it to the earth instead of passing through the building, protecting its structure and occupants.</p> Signup and view all the answers

    Explain the principle behind charging by induction and provide an example of how it works.

    <p>Charging by induction involves using a charged object to influence the charge distribution within a conductor without direct contact. When a positively charged rod is brought near a neutral conductor, the electrons in the conductor are attracted towards the rod, creating a temporary separation of charges. This results in the conductor having a negative charge on the side near the rod and a positive charge on the opposite side. The conductor remains neutral overall, but its charge distribution is influenced by the charged object.</p> Signup and view all the answers

    What is the role of the copper plate buried deep in the ground in a lightning conductor?

    <p>The copper plate acts as a ground terminal, providing a low-resistance path for the lightning current to flow safely to the earth. The larger the surface area of the plate, the lower the resistance and the more effectively it can dissipate the electrical energy.</p> Signup and view all the answers

    Why is it important to use electrical appliances with proper grounding?

    <p>Grounding provides a safe path for current to flow to the earth in case of a short circuit or a live wire touching the appliance's metal casing. This diverts the current away from the user, significantly reducing the risk of electric shock.</p> Signup and view all the answers

    Describe the principle of conservation of charges and how it applies to static electricity.

    <p>The principle of conservation of charges states that the total electric charge in an isolated system remains constant. In static electricity, when two objects are rubbed together, electrons are transferred. One object becomes positively charged due to electron loss, while the other gains electrons and becomes negatively charged. The total amount of positive and negative charge remains the same, illustrating the conservation of charges.</p> Signup and view all the answers

    Explain how a glass rod becomes positively charged when rubbed with silk.

    <p>When a glass rod is rubbed with silk, electrons are transferred from the glass rod to the silk. This leaves the glass rod with a deficiency of electrons, making it positively charged.</p> Signup and view all the answers

    Describe the process of charging a metal rod negatively by induction.

    <p>A positively charged glass rod is brought near the metal rod. The free electrons in the metal rod are attracted towards the positively charged glass rod, accumulating at the end closest to it. This end gains a negative charge, while the opposite end gains a positive charge. Touching the positively charged end with your hand allows electrons to flow from your body to neutralize the positive charge. Removing the glass rod and your hand leaves the metal rod negatively charged, with the negative charge distributed throughout.</p> Signup and view all the answers

    How does a pith ball electroscope work to determine the charge of an object?

    <p>A pith ball electroscope utilizes the principle of electrostatic repulsion. If a charged object is brought near the pith ball, the ball will either move away (if the charges are the same) or move towards (if the charges are opposite) the object, indicating the nature of the charge present on the object.</p> Signup and view all the answers

    Explain the construction of a gold leaf electroscope and how it works to detect the presence of charge.

    <p>A gold leaf electroscope consists of two thin gold or aluminum leaves hanging from a brass rod. The rod has a brass disc at its upper end and passes through an ebonite cork fitted into a glass bottle. The glass bottle has earthed tin foil on its sides. When a charged body is touched to the disc, the leaves acquire the same charge through conduction. The leaves then repel each other due to like charges, causing them to diverge. The degree of divergence indicates the amount of charge present on the body.</p> Signup and view all the answers

    How can you determine the type of charge on a body using a charged gold leaf electroscope?

    <p>If you know the charge on the electroscope, you can determine the charge of a body brought in contact. If the leaves diverge further, the body has the same charge as the electroscope. If the leaves converge, the body has the opposite charge.</p> Signup and view all the answers

    Describe the phenomenon of lightning and how a lightning conductor protects buildings.

    <p>Lightning occurs during thunderstorms when charged clouds pass over the earth or other clouds. The electric field between the charged cloud and the ground becomes strong enough to cause a spark, which is lightning. A lightning conductor, consisting of a long copper rod with spikes attached to a grounded copper plate, utilizes induction. When a charged cloud passes nearby, an opposite charge is induced on the spikes, which then flows to ground through the rod, preventing a direct strike and protecting the building.</p> Signup and view all the answers

    List three safety measures to observe during a thunderstorm.

    <ol> <li>Avoid standing under a tree or near a tall building. 2. Don't carry an umbrella as it can attract lightning. 3. Unplug electronic devices, avoid using wired telephones, and stay away from windows.</li> </ol> Signup and view all the answers

    What is the main purpose of the grounded copper plate in a lightning conductor?

    <p>The grounded copper plate acts as a pathway for the induced charge to flow into the earth. This ensures that the lightning strike does not damage the building and is safely discharged into the ground.</p> Signup and view all the answers

    Explain why a 15A fuse wire is thicker than a 5A fuse wire, and how this thickness relates to the current rating of the fuse.

    <p>The thickness of a fuse wire is directly proportional to its current rating. A 15A fuse wire needs to be thicker than a 5A fuse wire because it needs to handle a larger current without overheating. A thicker wire offers less resistance to the flow of current, reducing the risk of overheating and melting.</p> Signup and view all the answers

    Explain why an MCB is superior to a fuse wire in terms of its operation and advantages.

    <p>MCBs are superior to fuse wires because they are more responsive, safer, and offer better protection. Unlike fuse wires, which require replacement after melting, MCBs can be reset after a short circuit or overload. They also provide faster interruption of current flow upon detecting an overload or fault, minimizing damage to the circuit and appliances. Moreover, MCBs are more reliable and provide a visual indication of the fault, aiding in quicker troubleshooting and resolution.</p> Signup and view all the answers

    Explain the reason why electrical appliances are connected in parallel in most household circuits. What would be the disadvantages of connecting them in series?

    <p>Appliances are connected in parallel in household circuits to allow each appliance to operate independently of others. This means each appliance receives the full voltage from the source, ensuring consistent performance. If appliances were in series, the failure of one appliance would interrupt the entire circuit, causing all other appliances to stop working. Additionally, in a series connection, the current would be the same throughout the circuit. This means that higher-power appliances would draw more current, potentially causing lower-power appliances to overheat or malfunction.</p> Signup and view all the answers

    Describe the role of the earth wire in an electrical appliance and explain how it contributes to safety.

    <p>The earth wire, usually colored green or green-yellow, provides a safe path for the flow of current in case of a fault. If an accidental electrical fault occurs in the appliance, the earth wire provides a low-resistance path for the fault current to flow directly to the ground. This prevents the appliance from becoming live and dangerous. Additionally, the high current flowing through the earth wire triggers the MCB or fuse, interrupting the circuit and preventing further hazards.</p> Signup and view all the answers

    Explain how an electric meter works to measure the amount of electrical energy consumed by a household, and describe the units used to quantify this energy.

    <p>An electric meter uses a rotating armature, driven by the flow of electric current. As more electricity is used, the armature rotates faster, and a counter mechanism records the rotations. The meter measures the amount of energy consumed in kilowatt-hours (kWh). One kilowatt-hour is equivalent to using one kilowatt of power for one hour. The electricity bill is determined by the total kWh consumed during a given billing period.</p> Signup and view all the answers

    Discuss the benefits of using an MCB over a fuse wire in terms of safety, convenience, and reliability.

    <p>MCBs offer greater safety by quickly interrupting the circuit in case of a fault, minimizing the risk of electrical hazards like fire or electric shock. They are also more convenient than fuse wires, as they can be reset after a fault rather than replaced. This reduces downtime and inconvenience. MCBs are generally more reliable, boasting a longer lifespan than fuse wires and providing consistent protection. They also offer a visual indication of the fault, aiding in troubleshooting even for non-technical individuals.</p> Signup and view all the answers

    Explain how a fuse wire protects electrical appliances from damage due to short circuits and voltage fluctuations.

    <p>A fuse wire is designed to break the circuit when an excessive current flows through it. During a short circuit, a low-resistance path forms, allowing a large amount of current to flow, which can overheat wires and cause damage. When this occurs, the fuse wire melts due to its low melting point, opening the circuit and preventing further current flow, thus protecting the appliance. Similarly, voltage fluctuations can cause currents to exceed safe limits, but the fuse wire will again melt and break the circuit, protecting the appliance from potential damage.</p> Signup and view all the answers

    Explain why it is important to use the correct fuse rating for an electrical appliance. Why is it dangerous to replace a blown fuse with a fuse of higher rating?

    <p>Using the correct fuse rating is crucial for safety and efficient operation. If the fuse rating is too low, it will blow frequently, interrupting the appliance's operation. However, using a fuse with a higher rating than recommended is dangerous. A higher-rated fuse will not melt even if excessive current flows, potentially causing overheating, fire hazards, or damage to the appliance. The correct fuse rating ensures that the fuse blows only in case of a fault, protecting the appliance from damage caused by overload or short circuit. It also helps to prevent fires and electrical hazards.</p> Signup and view all the answers

    Explain the process of charging a metal rod negatively by induction, focusing on the movement of electrons and the role of the positively charged glass rod.

    <p>When a positively charged glass rod is brought near a metal rod, it attracts the free electrons in the metal rod towards the end closest to the glass rod. This creates a separation of charge, with the end near the glass rod becoming negatively charged and the far end becoming positively charged. Touching the far end of the metal rod with your hand allows electrons from the earth to flow into the metal rod, neutralizing the positive charge at that end. Removing both the glass rod and your hand simultaneously leaves the metal rod with a net negative charge due to the excess electrons at the end closest to the glass rod.</p> Signup and view all the answers

    Describe the principle of operation of a gold leaf electroscope. Explain how it can be used to determine the nature of a charge on a body.

    <p>A gold leaf electroscope utilizes the principle of electrostatic repulsion. When a charged object is brought near the brass disc of an uncharged electroscope, the leaves diverge due to the repulsion between like charges. If the leaves diverge further when the charged body is touched to the disc, the body has the same charge as the electroscope. Conversely, if the divergence decreases, the body has the opposite charge. The electroscope's initial charge determines whether the body is positively or negatively charged.</p> Signup and view all the answers

    Explain the role of a lightning conductor in protecting a building during a thunderstorm. Describe how it functions based on the principle of induction.

    <p>During a thunderstorm, charged clouds induce an opposite charge on the pointed ends of a lightning conductor. This accumulation of charge creates a path of least resistance for lightning to discharge to the ground through the copper rod connected to the earth. The lightning conductor effectively diverts the lightning strike away from the building, preventing damage and potential harm.</p> Signup and view all the answers

    Illustrate the process of charging by conduction, highlighting the role of electrons in transferring the charge between objects.

    <p>Charging by conduction involves the transfer of charge through direct contact between a charged object and a neutral object. When a positively charged object touches a neutral object, electrons from the neutral object are attracted to the positively charged object. This results in a net loss of electrons from the neutral object, leaving it positively charged. Similarly, a negatively charged object would transfer electrons to a neutral object, making it negatively charged.</p> Signup and view all the answers

    Explain the concept of lightning, focusing on its occurrence during a thunderstorm. Briefly describe its potential dangers.

    <p>Lightning is a sudden electrical discharge that occurs between two oppositely charged regions. During a thunderstorm, charged cloud formations create potential differences, leading to a breakdown of air insulation and the flow of a massive current. This spark is known as lightning and it is a highly dangerous phenomenon. Lightning strikes can cause severe damage to buildings, equipment, and even kill humans and animals.</p> Signup and view all the answers

    Discuss three key safety measures that one should adopt during a thunderstorm.

    <p>During a thunderstorm, it is crucial to prioritize safety. Some essential measures include: 1) Avoiding standing under trees or near tall buildings, as these can attract lightning strikes. 2) Avoiding carrying umbrellas, especially in open areas, as the metal frame can provide a path for lightning. 3) Unplugging electrical appliances, including televisions, computers, and phones, to minimize the risk of damage from power surges caused by lightning strikes.</p> Signup and view all the answers

    Compare and contrast the charging by conduction and charging by induction. Provide examples of each charging method.

    <p>Charging by conduction involves direct contact between a charged object and a neutral object, transferring charge through the flow of electrons. In charging by induction, the charged object influences the distribution of charges in the neutral object without direct contact, resulting in a separation of charges. An example of conduction is rubbing a charged rod against a neutral object, while an example of induction is bringing a charged rod near a neutral object. Both methods lead to charged objects, but they differ in the mechanism of charge transfer.</p> Signup and view all the answers

    Explain the difference between a pith ball electroscope and a gold leaf electroscope. Briefly outline the principle of operation for both.

    <p>Both electroscopes utilize electrostatic repulsion, but they differ in their construction and sensitivity. A pith ball electroscope consists of a small, lightweight ball of pith suspended by a thread, while a gold leaf electroscope features two thin, delicate gold or aluminum leaves. The pith ball electroscope is less sensitive and primarily detects the presence of charge, while the gold leaf electroscope is more sensitive and can also indicate the type of charge. Both operate on the principle that like charges repel, causing the leaves or the pith ball to diverge from their neutral position when a charged object is brought near or into contact.</p> Signup and view all the answers

    Describe the concept of electrostatic induction. Provide an example of how it can be used to explain the operation of a lightning conductor.

    <p>Electrostatic induction refers to the separation of charges within a neutral object due to the influence of a nearby charged object without physical contact. The charged object attracts opposite charges in the neutral object, causing a polarization of charge. For example, when a charged cloud approaches a building equipped with a lightning conductor, the sharp points of the conductor induce an opposite charge on their surface. This opposite charge provides a path for the lightning to discharge to the ground through the conductor, diverting it away from the building and minimizing damage.</p> Signup and view all the answers

    Discuss the concept of electrical potential difference. Explain how it relates to the flow of electric current.

    <p>Electrical potential difference, also known as voltage, represents the work required to move a unit of charge between two points in an electric field. It's the driving force that causes electric current to flow. A larger potential difference between two points results in a greater force pushing charges, leading to a stronger current. Essentially, voltage creates the necessary energy for electrons to move from a higher potential to a lower potential, generating electric current.</p> Signup and view all the answers

    Explain why a parallel arrangement of electrical appliances in a household circuit is preferred compared to a series arrangement, providing at least two reasons.

    <p>In a parallel circuit, each appliance has its own separate path for current, so if one appliance fails, the others continue to function. Also, each appliance receives the full voltage of the circuit, allowing them to operate independently and at their designated power level.</p> Signup and view all the answers

    Describe the process of charging a metal rod positively by conduction, detailing the transfer of charges and the resulting charge on the rod.

    <p>A positively charged object, like a glass rod rubbed with silk, is brought into contact with the metal rod. The positive charges from the charged object transfer to the metal rod, resulting in a net positive charge on the metal rod.</p> Signup and view all the answers

    Explain the function of an earth wire in a household electrical appliance, outlining the circumstances under which it becomes crucial for safety and how it mitigates potential hazards.

    <p>The earth wire provides a low-resistance pathway for electric current to flow to the ground, preventing a build-up of charge on the appliance's metal casing. If a fault occurs, like a live wire touching the casing, the current flows to the ground through the earth wire, preventing electric shock to anyone touching the appliance.</p> Signup and view all the answers

    Compare and contrast the operation of a Miniature Circuit Breaker (MCB) with a fuse wire in terms of their tripping mechanism, reset capability, and overall advantages.

    <p>An MCB uses a magnetic or thermal mechanism to trip the circuit when a fault occurs, while a fuse wire melts due to excessive current. MCBs can be reset by simply flipping a switch, while fuse wires need to be replaced after a fault. MCBs offer advantages like faster response times, higher safety, and greater flexibility in handling circuit loads.</p> Signup and view all the answers

    Explain, using examples, how rubbing two objects together can lead to static electricity, considering the transfer of electrons and the resulting charges on the objects.

    <p>When a glass rod is rubbed with silk, electrons are transferred from the glass rod to the silk. This leaves the glass rod with a net positive charge and the silk with a net negative charge. Similarly, rubbing an ebonite rod with fur transfers electrons from the fur to the ebonite rod, resulting in a negatively charged ebonite rod and a positively charged fur.</p> Signup and view all the answers

    Explain the principle of conservation of charges in the context of rubbing two objects together. Provide an example to illustrate your explanation.

    <p>The principle of conservation of charges states that the total charge in a system remains constant. When two objects are rubbed, electrons are transferred from one object to another. The object that loses electrons becomes positively charged, and the object that gains electrons becomes negatively charged. However, the total amount of charge in the system remains the same. In the case of a glass rod rubbed with silk, the glass rod loses electrons becoming positively charged, and the silk gains those electrons becoming negatively charged. The total charge of the system, however, remains neutral because the number of positive charges on the glass rod is equal to the number of negative charges on the silk.</p> Signup and view all the answers

    Describe the composition of an atom, including the location and charges of its subatomic particles. Explain how the atom maintains electrical neutrality.

    <p>An atom consists of three main particles: protons, neutrons, and electrons. Protons carry a positive charge and reside in the nucleus at the center of the atom. Neutrons, with no charge, also reside in the nucleus. Electrons, carrying a negative charge, orbit around the nucleus in different energy levels. An atom is electrically neutral because the number of positively charged protons is equal to the number of negatively charged electrons.</p> Signup and view all the answers

    What are conductors and insulators? Explain the difference in their electrical conductivity and provide one example of each.

    <p>Conductors are substances that allow electricity to flow easily through them due to the presence of free electrons. Examples include metals like copper, silver, and aluminum. Insulators, on the other hand, have very few or no free electrons, making them poor conductors of electricity. Examples include wood, rubber, and glass.</p> Signup and view all the answers

    Explain the concept of charging by induction, detailing the process and the type of charge induced on the object.

    <p>Charging by induction involves bringing a charged object (inducer) near an uncharged conductor (induced object) without touching it. The presence of the charged inducer causes a redistribution of charges within the conductor. For example, if a positively charged object is brought near a conductor, negative charges in the conductor will be attracted towards the charged object, leaving the opposite side with a net positive charge. The induced object is then charged without direct contact with the inducer, and the charge induced is opposite to the charge of the inducer.</p> Signup and view all the answers

    Describe two scenarios that can lead to a short circuit in a household electrical system and explain how these scenarios can be prevented.

    <p>Two scenarios that can lead to a short circuit are: 1) Broken insulation in wiring causing live wires to touch neutral wires or the appliance casing, and 2) High current flow due to voltage fluctuations exceeding the wire's capacity. These scenarios can be prevented by using proper insulation on wires, ensuring proper installation and maintenance, and using circuit protection devices like MCBs to prevent excessive current flow.</p> Signup and view all the answers

    Explain why two ebonite rods rubbed with fur repel each other when brought close whereas two rods, one rubbed with silk and the other with fur, attract each other.

    <p>Ebonite rods rubbed with fur acquire a negative charge because electrons transfer from the fur to the rod. As both rods have the same negative charge, they repel each other. When a glass rod is rubbed with silk, the glass rod loses electrons becoming positively charged, and the silk becomes negatively charged. Since the charges are opposite, the glass rod and the ebonite rod attract each other.</p> Signup and view all the answers

    Imagine you're designing a new safety feature for household electrical systems. What is the main principle behind how this feature would work and what specific safety benefit would it provide?

    <p>The safety feature would likely be based on Ground Fault Circuit Interrupter (GFCI) technology. It works by constantly monitoring the current flowing through the live and neutral wires. If there is a difference in current, indicating a ground fault (like someone touching a faulty appliance), the GFCI immediately trips, interrupting the flow of electricity, minimizing the risk of electric shock.</p> Signup and view all the answers

    Explain how a lightning conductor works to protect a building from a lightning strike, detailing the path of electricity through the system and its ultimate destination.

    <p>A lightning conductor consists of a metal rod mounted at the highest point of the building connected to a thick copper wire that runs down the building to a grounding rod buried deep into the ground. When lightning strikes the building, the conductor provides a low-resistance path for the electricity to flow through the wire to the ground rod. This diverts the electricity safely into the ground, minimizing the risk of damage to the building and people within.</p> Signup and view all the answers

    Detail the process of charging a glass rod positively when rubbed with silk, addressing the transfer of particles, the resulting charges on both objects, and the type of charge acquired by the glass rod.

    <p>When a glass rod is rubbed with silk, free electrons from the glass rod transfer to the silk. This leaves the glass rod with fewer electrons, giving it a net positive charge. The silk, having gained electrons, becomes negatively charged. The glass rod acquires a <em>positive</em> charge due to the loss of electrons.</p> Signup and view all the answers

    Explain why an ebonite rod rubbed with fur acquires negative charge, tracing the pathway of electrons during rubbing and the resulting charge distribution.

    <p>When an ebonite rod is rubbed with fur, the electrons from the fur are transferred to the ebonite rod, leaving the fur with a deficit of electrons and a net positive charge. The ebonite rod, now possessing more electrons, gains a net negative charge. The charge on the ebonite rod is determined by the number of electrons it gains from the fur.</p> Signup and view all the answers

    In the context of electricity at rest, describe the conditions necessary for an electric current to flow and discuss what happens to the electrons in a material when an electric current is present.

    <p>For electricity to flow, there must be a difference in potential, also known as voltage, between two points. This potential difference creates an electric field within the material, which acts as a force on free electrons in the material. When a current flows, these free electrons move through the material from the region of higher potential to the region of lower potential, creating the flow of charge known as an electric current.</p> Signup and view all the answers

    Flashcards

    Fuse Wire

    A wire with a low melting point that protects circuits by melting under excess current.

    Electric Meter

    A device measuring electric energy consumption in kWh.

    kWh

    Unit of electric energy equivalent to one kilowatt used for one hour.

    Short Circuit

    An unintended connection that allows current to flow without proper resistance.

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    Parallel Connection

    A wiring configuration where appliances are connected side by side, allowing independent operation.

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    M.C.B.

    Miniature Circuit Breaker, a protective device that automatically switches off when current exceeds its rating.

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    Current Rating

    The maximum current a fuse wire can safely carry.

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    Fuse Function

    To protect electrical appliances from damage by disconnecting when excess current flows.

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    Parallel Circuit

    A circuit arrangement where each appliance operates independently.

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    Live Wire

    Wire that carries voltage; usually red or brown.

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    Neutral Wire

    Wire that completes the circuit; color is black or light blue.

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    Earth Wire

    Provides safety by transferring current to the ground; colored green or yellow.

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    Electricity at Rest

    Electric charge that is not in motion or flowing.

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    Conservation of Charges

    Total charge remains the same after rubbing two objects together.

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    Conductors

    Substances with many free electrons that allow electricity to flow.

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    Insulators

    Substances with few or no free electrons preventing electricity flow.

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    Charging by Conduction

    Method where a charged object touches a conductor to transfer charge.

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    Charging by Induction

    Charging a conductor without direct contact with a charged object.

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    Electrons in an Atom

    Negatively charged particles that orbit the nucleus of an atom.

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    Protons in an Atom

    Positively charged particles that reside in an atom's nucleus.

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    Electroscope

    A device used to detect the presence and nature of electric charge.

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    Pith Ball Electroscope

    A type of electroscope using a lightweight pith ball to determine charge type.

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    Gold Leaf Electroscope

    An electroscope made of gold leaves that diverge to show charge presence.

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    Positive Charge Induction

    When a positively charged object is brought near, causing charge separation.

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    Lightning

    A natural electrical discharge that occurs between clouds or ground, causing sparks.

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    Lightning Conductor

    A device designed to protect structures from lightning strikes by directing the charge to the ground.

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    Safety Measures During Thunderstorm

    Precautions to take to avoid lightning-related dangers during storms.

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    Induced Charge

    A temporary charge that occurs when an object is brought near a charged body, creating polarity.

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    Divergence of Leaves

    The spreading apart of leaves in an electroscope indicating the presence of charge.

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    Function of a Fuse

    A device that melts to prevent excess current in a circuit.

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    How Fuse Works

    Fuse melts when current exceeds safe limits, breaking the circuit.

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    Fuse Wire Thickness

    Thicker fuse wire is rated for higher currents; 15A wire is thicker than 5A.

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    Electric Meter Placement

    Electric meter is installed after the company fuse in the electric cable.

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    kWh Meter Purpose

    Measures electrical energy consumption for billing purposes in kWh.

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    Schneider Circuit Breaker (M.C.B.)

    Automatically disconnects the circuit when current exceeds limits, superior to fuses.

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    Voltage Fluctuation Protection

    Fuse protects appliances from damage due to voltage spikes or short circuits.

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    Current Flow and Electric Meter

    When in use, current flows and rotates a meter's armature, recording energy consumption.

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    Miniature Circuit Breaker (M.C.B.)

    A device that quickly switches off a circuit to prevent damage.

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    Short Circuit Causes

    Occurs when live wire contacts neutral wire due to insulation failure.

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    Household Circuit Preference

    Parallel arrangements are preferred because each appliance operates independently.

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    Electrical Insulation

    Materials that prevent the flow of electricity, ensuring safety.

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    Charging by Rubbing

    Process where two objects acquire opposite charges when rubbed together.

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    Positive and Negative Charge

    When one object loses electrons, becoming positive, while the other gains them, becoming negative.

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    Atom Composition

    Atoms consist of electrons, protons, and neutrons; protons are positively charged, electrons negatively charged.

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    Net Charge of an Atom

    An atom is electrically neutral because it has equal numbers of protons and electrons.

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    Charge Transfer Mechanism

    When two objects touch, free electrons move, resulting in opposite charges.

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    Ebonite Rod and Fur Rubbing

    Rubbing an ebonite rod with fur transfers electrons from fur to rod, making rod negatively charged.

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    Glass Rod and Silk Rubbing

    When a glass rod is rubbed with silk, electrons transfer from glass to silk, making glass positively charged.

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    Conduction vs. Induction

    Two ways to charge a conductor: by direct contact (conduction) or without contact (induction).

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    Conductor Characteristics

    Materials with many free electrons allowing electricity to flow easily.

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    Insulator Characteristics

    Materials that resist electric flow, often lacking free electrons.

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    Safety from Electric Shock

    Connecting appliances to earth wires protects from shocks by grounding excess current.

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    Electroscope Function

    Detects the presence and nature of electric charge on a body.

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    Induction Charge in Clouds

    When charged clouds induce opposite charges in nearby objects or other clouds.

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    Effect of Lightning

    Lightning can cause fires, destroy buildings, and kill living beings.

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    Acquired Charge

    The charge gained by an object after interaction with another charged object.

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    Fuse Wire Melting Point

    Fuse wire has a low melting point to melt under excess current, protecting circuits.

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    Purpose of Electric Meter

    Measures the amount of electric energy consumed in kWh for billing purposes.

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    Current Flow Effect

    When current flows, it rotates the armature in the electric meter to measure energy usage.

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    Short Circuit and Fuse Response

    In a short circuit, the fuse wire melts due to high temperature, breaking the circuit and preventing damage.

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    Appliances in Parallel Connection

    Connecting appliances in parallel allows separate operation; if one fails, others continue to work.

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    Induced Charge in Thunderstorms

    Clouds acquire opposite charges by induction, causing lightning.

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    Construction of Gold Leaf Electroscope

    Consists of gold leaves on a brass rod inside a glass container, detecting charge by divergence.

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    M.C.B. Reset

    Miniature Circuit Breaker can be reset after tripping.

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    Earth Wire Function

    Earth wire protects against electric shock by directing current to the ground.

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    Short Circuit Result

    Occurs when live wire contacts neutral wire due to insulation failure.

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    Insulation Breakdown

    When wire insulation fails, it can lead to dangerous short circuits.

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    Charges in Rubbing

    Rubbing transfers electrons, creating opposite charges.

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    Positive Charge Creation

    When an object loses electrons, it becomes positively charged.

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    Negative Charge Creation

    When an object gains electrons, it becomes negatively charged.

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    Atom Neutrality

    Atoms remain neutral because protons and electrons are equal.

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    Conduction Charging

    Charging by conduction occurs when a charged object touches another.

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    Induction Charging

    Charging without direct contact, causing charge separation.

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    Free Electrons

    Free electrons in conductors allow easy electricity flow.

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    Insulator Properties

    Insulators have few or no free electrons, resisting electric flow.

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    Charge Conservation

    Total charge remains constant when two objects are rubbed together.

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    Electric Meter Function

    Measures electric energy in kWh for billing consumers.

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    Household Circuits

    Appliances are connected in parallel for independent operation.

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    Short Circuit Consequence

    Occurs when live wire touches neutral, causing excess current.

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    M.C.B. Advantages

    Miniature Circuit Breaker reacts faster and resets easily compared to fuses.

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    Purpose of a Fuse

    Limits current flow to protect appliances from damage.

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    Voltage Fluctuation Effect

    Fuse prevents damage from sudden voltage changes.

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    Electric Meter Location

    Installed after the company fuse on the incoming cable.

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    Determining Charge Type with Pith Ball

    If a positively charged body is near a pith ball, it moves away; if negatively charged, it moves closer.

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    Charge Transfer in Metals

    When a charged object touches a metal, it transfers charge due to free electrons.

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    Circuit Breaker Reset

    The action of raising a tripped M.C.B. back to its working state.

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    Short Circuit Description

    A fault condition where live wire contacts neutral wire, causing excessive current flow.

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    Insulation Failure Consequences

    Breakdown of wire insulation which can lead to dangerous short circuits and potential shocks.

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    Parallel Circuit Advantage

    In parallel circuits, each appliance functions independently, ensuring uninterrupted operation.

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    Live Wire Identification

    The wire that carries electric current, often colored red or brown.

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    Earth Wire Purpose

    Directs excess current to the ground to prevent electrical shocks.

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    Charge Transfer

    The movement of electrons from one object to another when rubbed together, creating opposite charges.

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    Atom Structure

    Atoms consist of protons, neutrons, and electrons; they are neutral overall due to equal numbers of protons and electrons.

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    Ebonite and Fur Rubbing

    Rubbing an ebonite rod with fur transfers electrons, making the rod negatively charged.

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    Glass and Silk Rubbing

    When a glass rod is rubbed with silk, electrons move from glass to silk, resulting in a positively charged glass rod.

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    Conductors vs. Insulators

    Conductors allow the flow of electricity (like metals), while insulators prevent it (like rubber).

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    Function of Miniature Circuit Breaker (M.C.B.)

    M.C.B. automatically disconnects when current exceeds safe limits.

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    Standard Electric Meter Placement

    Electric meter is installed after the company fuse on the incoming cable.

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    Operation of Electric Meter

    As current flows, it rotates the meter's armature to measure energy.

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    Reason for Parallel Connection in Circuits

    Appliances in parallel allow them to operate independently.

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    Electric Meter Measurement Unit

    Electric energy consumption is measured in kWh (kilowatt hour).

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    Short Circuit Effect on Fuse

    In a short circuit, the fuse wire melts, breaking the circuit.

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    Fuse Wire and Current Rating

    Thicker fuse wire is rated for higher currents, like 15A vs 5A.

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    Independent Operation in Circuits

    In parallel circuits, each appliance operates independently without affecting others.

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    Charge During Rubbing

    When two objects are rubbed together, electrons transfer, creating opposite charges.

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    Positive Charge Definition

    Occurs when an object loses electrons, resulting in a net positive charge.

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    Properties of Conductors

    Materials with many free electrons allowing electricity to flow easily (e.g., metals).

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    Effects of Voltage Fluctuation

    Can cause excessive current flow, potentially leading to damage in electrical systems.

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    Insulating Material Examples

    Common insulators include wood, paper, and glass that do not allow electricity to flow.

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    Charge Detection

    The process of using devices like electroscopes to determine if an object is charged and its type.

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    Divergence of Leaves in Gold Leaf Electroscope

    The spreading apart of the leaves indicating the presence of electric charge.

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    Fuse Melting Point

    Fuse wire melts at about 200°C, protecting circuits by breaking connection.

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    Miniature Circuit Breaker

    M.C.B. automatically disconnects circuits when excess current flows, preventing damage.

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    Role of Fuse in Circuits

    Limits the current to protect appliances from excess current damage.

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    Short Circuit Effects

    Occurs when live wire contacts neutral wire, leading to potential damage.

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    Parallel Connection Advantages

    Appliances connected in parallel can operate independently, ensuring continuity.

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    Electric Meter Installation

    Located after the company fuse in the electric cable for accurate usage measurement.

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    Fuses and Voltage Fluctuations

    Fuses protect circuits by breaking connection during voltage spikes or fluctuations.

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    Electroscope Types

    There are two main types: Pith ball and Gold leaf electroscopes for detecting charge.

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    Induced Charge and Lightning

    During storms, clouds induce opposite charges nearby, which can lead to lightning strikes.

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    Construction of Lightning Conductor

    A rod with spikes that directs lightning to the ground, protecting buildings from strikes.

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    Function of Lightning Conductor

    Protects buildings by transferring the charge of a lightning strike safely to the ground.

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    Live Wire Color

    The wire that carries voltage, usually red or brown.

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    Neutral Wire Color

    Completes the circuit; black or light blue in color.

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    Characteristics of Insulators

    Insulators do not allow the flow of electricity and cannot be easily charged by rubbing.

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    Ebonite Rod and Fur

    Rubbing them transfers electrons from fur to ebonite, charging the rod negatively.

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    Glass Rod and Silk

    Rubbing a glass rod with silk transfers electrons from glass to silk, giving the rod a positive charge.

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    Fuse Wire Characteristics

    Fuse wire has a low melting point to protect circuits from excess current.

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    M.C.B. vs Fuse

    M.C.B. automatically disconnects during overload, superior to traditional fuse wires.

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    Function of Electric Meter

    Measures electric energy consumed in kWh for billing.

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    Electric Meter Operation

    Current flow rotates the meter's armature, recording energy consumption.

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    Effect of Short Circuit

    A fault where live wire touches neutral, causing excessive current flow.

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    Current Rating and Thickness

    Thicker fuse wire can handle a higher current rating.

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    Pith Ball Electroscope Function

    Detects charge type; if the pith ball moves away, the charge is positive, if it moves closer, it is negative.

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    Gold Leaf Electroscope Operation

    Gold leaves diverge when charged; used to determine if a body is charged and its type.

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    Lightning Conductor Purpose

    Device that protects buildings from lightning by directing charge safely to the ground.

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    Safety During Thunderstorms

    Precautions include avoiding tall objects, unplugging electronics, and not using wired phones.

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    Charge Detection with Electroscopes

    Electroscopes detect charge presence; divergence indicates charging direction and type.

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    Insulation Breakdown Consequence

    Failure of wire insulation may lead to a short circuit, increasing the risk of electric shock.

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    Live, Neutral, Earth Wire Colors

    Live wire is red or brown; neutral is black or light blue; earth is green or yellow, indicating their functions.

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    Independent Appliance Operation

    In a parallel circuit, each appliance operates separately, so one failure doesn’t affect others.

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    Rubbing Objects Charge Transfer

    When two objects are rubbed together, free electrons move, creating equal but opposite charges.

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    Ebonite and Fur Interaction

    When rubbed together, electrons move from fur to ebonite, charging the rod negatively and the fur positively.

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    Glass and Silk Charge Interaction

    When a glass rod is rubbed with silk, electrons transfer from glass to silk, resulting in a positively charged glass rod.

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    MCB vs Fuse

    MCB is a circuit breaker that automatically resets when current exceeds limits, unlike a fuse.

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    Importance of Parallel Connection

    Allows appliances to operate independently even if one fails.

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    Fuse Wire Thickness and Rating

    Thicker fuse wire can carry higher current ratings safely.

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    Miniature Circuit Breaker (M.C.B.) vs Fuse

    M.C.B. switches off quickly and can be reset, while a fuse needs replacement after use.

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    Household Parallel Circuit Benefits

    In a parallel circuit, each appliance operates independently, unaffected by others' failure.

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    Live Wire Characteristics

    The live wire carries voltage, typically colored red or brown.

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    Neutral Wire Function

    The neutral wire completes the circuit and is usually black or light blue.

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    Electron Transfer in Rubbing

    When two objects are rubbed, electrons transfer, creating positive and negative charges.

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    Conductor Examples

    Metals like silver, copper, and aluminum allow electricity to flow easily.

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    Effects of Insulation Failure

    Broken insulation may cause dangerous short circuits or shocks.

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    Current Limitation

    A fuse wire limits current flow to protect appliances from excessive current damage.

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    Electric Meter Functionality

    Electric meters measure energy consumption in kilowatt-hours (kWh) for billing purposes.

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    Parallel Connection Appliance Benefit

    In parallel circuits, if one appliance fails, others continue to operate independently.

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    Miniature Circuit Breaker (M.C.B.) Function

    M.C.B. disconnects the circuit automatically when current exceeds safe limits.

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    Pith Ball Electroscope Use

    Determining charge type by observing the movement of a charged pith ball near another body.

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    Gold Leaf Electroscope Function

    Detects electric charge presence by leaf divergence when a charged body is brought close.

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    Induced Charge in Clouds

    A process where clouds gain opposite charges that can lead to electrical discharge.

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    Touching Electroscope

    When a charged object touches an electroscope, it transfers charge causing leaf divergence.

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    Household Circuit Arrangement

    Appliances are connected in parallel for independent operation.

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    Insulation Failure

    Breakdown of wire insulation leading to possible short circuits.

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    Ebonite Rod Charging

    Rubbing an ebonite rod with fur transfers electrons, making it negatively charged.

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    Glass Rod Charging

    When a glass rod is rubbed with silk, it loses electrons, becoming positively charged.

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    Atoms

    Composed of protons, neutrons, and electrons; neutral when balanced.

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    Connection of Appliances

    In houses, appliances are connected in parallel.

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    Short Circuit Protection

    Fuses melt to break the circuit during a short circuit.

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    Difference Between M.C.B. and Fuse

    M.C.B. can reset after tripping, unlike fuses.

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    Current and Wire Thickness

    Thicker fuse wire is used for higher current ratings.

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    Short Circuit Warning

    Occurs when a live wire touches a neutral wire, causing excess current flow.

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    Function of Earth Wire

    Earth wire protects against electric shock by directing excess current to the ground.

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    Glass Rod and Silk Charge

    When a glass rod is rubbed with silk, it becomes positively charged as electrons move to silk.

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    Ebonite Rod and Fur Charge

    Rubbing an ebonite rod with fur makes the rod negatively charged due to electron transfer.

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    Movement of Free Electrons

    Free electrons in conductors allow them to easily conduct electricity.

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    Insulator Function

    Insulators prevent electricity flow due to lack of free electrons.

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    Charging by Rubbing Mechanism

    Rubbing transfers electrons, leading to opposite charges on two objects.

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    Atom Charge Neutrality

    Atoms are neutral as they have equal numbers of protons and electrons.

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    M.C.B. Functionality

    Miniature Circuit Breaker disconnects when current exceeds safe limits.

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    Function of M.C.B.

    Miniature Circuit Breaker switches off automatically when current exceeds limits.

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    Household Circuit Connection

    All appliances in a household circuit are connected in parallel for independent operation.

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    End Charge in Induction

    In charging by induction, the side of the object near the charged object acquires an opposite charge.

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    Conducting Charges in Electroscope

    In a gold leaf electroscope, charge conducted causes leaves to separate when touched by a charged body.

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    Circuit Protection with Earthing

    Connecting the metal covering of appliances to earth wire prevents shocks.

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    Free Electrons Role

    Free electrons in conductors allow easy flow of electricity.

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    Neutral Wire Characteristics

    Wire that completes the circuit; usually colored black or light blue.

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    Study Notes

    Household Electricity

    • Fuses: Prevent appliance/circuit damage by melting when excessive current (above rating) flows. Located in the live wire. Thicker wires have higher current ratings. Limit current, protect circuits from short circuits or voltage fluctuations. Melt at approximately 200°C. A low melting point allows the wire to melt when a large current passes through it, preventing further damage. Fuse wires limit current and protect the circuit. A fuse wire should have a low melting point so that when a large amount of current passes through it, the wire will melt and does not allow excess current to pass, thus protecting the appliance or circuit from getting damaged.
    • Parallel Connections: Household appliances operate independently; failure of one doesn't affect others. Each operates at the same voltage with its own current path, allowing individual switches. Preferred for better functionality and safety. All appliances are connected in parallel configurations. If one appliance fails, others remain unaffected. Two bulbs connected in parallel ensure that if one bulb fails, the other continues to glow. This is a better setup for independent appliance functionality, and safety.
    • Electric Meters: Measure energy consumption in kilowatt-hours (kWh). Connected after the company's fuse to the house's electrical cable. Typically mounted on the front or outside wall; measure electric energy for billing. Measure the amount of energy consumed. Electric meters are used to measure electric energy consumed by the consumer. Energy is measured in B.O.T (Board of Trade) units or kilowatt-hours (kWh). The electric current flow in the circuit rotates the meter's armature, and rotations are counted to determine the energy consumed.
    • Circuit Protection: Fuses limit current, protecting circuits from short circuits or voltage fluctuations. When current exceeds fuse rating, the fuse wire melts, creating an open circuit, preventing further damage. Fuses are connected in the live wire. Short circuits/voltage fluctuations cause maximum current flow, leading to potential wire damage. The melting fuse wire creates an open circuit, stopping current flow and preventing further harm. A fuse protects electrical circuits from harm caused by short circuits and voltage fluctuations. During short circuiting or voltage fluctuations, maximum current passes through the wires causing burning of the wires. To prevent this damage, a fuse is connected to the live wire of the circuit. When a short circuit occurs, the fuse wire gets heated to melt it. This creates a gap in the live wire, breaking the circuit. No current flows, therefore protecting electrical appliances or circuits from further damage.
    • Miniature Circuit Breakers (MCBs): Interrupt circuits much faster (25 milliseconds) and are resettable. Fuses require replacement. MCBs provide more protection, flexibility, and safety. Faster circuit interruption than fuses, with the ability to reset instead of replace. The full form of MCB is miniature circuit breaker. MCB is superior to the fuse wire for these reasons: MCB switches off the circuit very quickly, it can be reset after tripping, and offers greater protection, flexibility, and safety.
    • Cable Wires: Household electrical cables have three wires: live (red/brown), neutral (black/light blue), and earth (green/yellow). Identifiable by color coding. If the insulation breaks, the live wire touches the neutral wire which results in a short circuit.
    • Earthing: Connecting appliance metal casings to the earth wire diverts excessive current to the ground, protecting users from electric shocks. Earthing prevents electric shocks by providing a direct path to the ground, diverting current away from the user. Live wires touching appliance bodies can cause fatal shocks; earthing prevents this by diverting current to the ground. This is critical for safety in electrical systems.
    • Switch: Disconnects the live wire. Switches are connected in the live wire. Switches disconnect the live wire to prevent current flow. When the switch of an appliance is turned off, it disconnects the live wire.
    • Appliance Safety: Parallel connections allow independent appliance switches, offering safety and control. Each appliance has an independent current path, working at the same voltage, and having a separate switch connected to its live wire.
    • Electricity Consumption: Measured in B.O.T (Board of Trade) units or kilowatt-hours (kWh).
    • Electric Meter Function: Measures electric energy consumed; used to calculate bills. The purpose of the kWh meter is to measure the amount of electric energy consumed by the consumer in kWh for which the electricity bill is paid by him to the electricity board.
    • Fuse Wire Thickness: Thickness of fuse wire depends on the current rating; higher rating means thicker wire. 15 A fuse wire is thicker than the 5 A fuse wire because the thickness of the fuse wire depends on its current rating.
    • Fuse wire melting point: Fuse wire melts at about 200°C.

    Static Electricity

    • Charging by Friction: Rubbing transfers electrons, creating equal and opposite charges; total charge remains constant. When two objects are rubbed, there is a transfer of free electrons. One body loses electrons and becomes positively charged, while the other gains equal electrons and becomes negatively charged.
    • Conservation of Charge: The total charge remains constant before and after rubbing; equal and opposite charges result. When two objects are rubbed together, both are charged equally but with opposite charges. Thus, the total charge before and after rubbing remains the same.
    • Charging a Conductor by Conduction: Touching a charged body to a conductor transfers charge of the same polarity to the conductor. In charging by conduction, a charged body is touched or brought into contact, and the resulting charge is the same as the charging body's charge.
    • Charging by Induction: Bringing a charged object near a conductor induces opposite charges, allowing charging without contact.
    • Electroscopes: Devices detect and identify charge type (positive or negative). Pith ball and gold leaf electroscopes differentiate charge types.
    • Lightning: Thunderstorms create opposite charges, leading to discharge (lightning). Lightning conductors mitigate damage by providing a safe path to the ground.
    • Charging by rubbing: Transfer of electrons results in opposite charges; total charge is conserved.
    • Types of Charges: Objects have positive or negative charges (e.g., glass rod/silk positive; ebonite/fur negative).
    • Electric charge at rest: Charge that is not moving or flowing. No current or energy transfer with stationary charge.
    • Rubbing and Charge: Rubbing transfers electrons, resulting in opposite charges. The total electrical charge is conserved.
    • Opposite Charges Attract: Objects with opposite charges attract.
    • Like Charges Repel: Objects with like charges repel.
    • Electroscope use: Detecting presence and type of charge. Pith ball and gold leaf electroscopes show charge type and amount.
    • Lightning Protection: Lightning conductors conduct current safely to the earth, protecting buildings.
    • Electron Transfer: Rubbing transfers electrons, resulting in different charges.

    Atomic Structure and Charge

    • Atoms: Atoms contain positively charged protons, neutrally charged neutrons, and negatively charged electrons orbiting the nucleus. Number of electrons and protons are equal; result in a neutral atom. The three constituents of an atom are electrons, protons, and neutrons. Electrons are negatively charged, protons are positively charged, and neutrons have no charge.
    • Conductors vs. Insulators: Conductors have many free electrons for current flow. Insulators have few free electrons and resist current flow. Conductors allow electricity to pass through them; insulators do not. Conductors contain many free electrons, while Insulators contain few or no free electrons. They can be charged by rubbing; insulators cannot. Metals are conductors; wood, paper, glass, and rubber are insulators.
    • Charging Conductor: Conductors can be charged by conduction or induction. Two methods of charging a conductor are conduction and induction.
    • Conservation of Charge: Total overall charge remains the same during charging processes.
    • Atomic structure: Protons (+), neutrons (neutral), and electrons (-) form atoms; net charge usually zero. Electrons orbit the nucleus. An atom has a nucleus containing protons (positively charged) and neutrons (no charge), and electrons (negatively charged) orbiting the nucleus. The number of electrons in an atom equals the number of protons, making the atom neutral.
    • Charging by contact/conduction: Transfer of charge through direct contact.
    • Charging by induction: Transfer of charge without contact, inducing opposite charges.
    • Electroscope use: Detecting presence and type of charge. Pith ball and gold leaf electroscopes show charge type and amount.
    • Lightning Protection: Lightning conductors conduct current safely to the earth, protecting buildings.
    • Electron Transfer: Rubbing transfers electrons, resulting in different charges on the objects.
    • Static Electricity: Explains the behavior of electric charges at rest, without current flow.

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    Description

    This quiz covers fundamental concepts of household electricity, including the function and importance of fuses, the advantages of parallel connections, and the role of electric meters. Additionally, it discusses circuit protection methods like miniature circuit breakers (MCBs) and their advantages over traditional fuses.

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