Multiple Choice Questions from.docx

Multiple Choice Questions from \"jesc111.pdf\"\ Electric Current and Circuits\ \ What is an electric current?\ (a) Flow of heat through a conductor\ (b) Flow of light through a conductor\ **(c) Flow of electric charge through a conductor**\ (d) Flow of water through a conductor\ What constitutes the...

Multiple Choice Questions from \"jesc111.pdf\"\ Electric Current and Circuits\ \ What is an electric current?\ (a) Flow of heat through a conductor\ (b) Flow of light through a conductor\ **(c) Flow of electric charge through a conductor**\ (d) Flow of water through a conductor\ What constitutes the flow of charge in metallic wires?\ (a) Protons\ (b) Neutrons\ (c) **Electrons\ **(d) Ions\ What is an electric circuit?\ (a) A broken path of electrical energy\ (b) A continuous and closed path of electric current\ (c) An open path of electric charge\ (d**) A discontinuous and open path of electric current\ **What is the SI unit of electric charge?\ (a) Ampere\ (b**) Coulomb**\ (c) Volt\ (d) Ohm\ What is the SI unit of electric current?\ (a**) Ampere**\ (b) Coulomb\ (c) Volt\ (d) Ohm\ How is an ammeter connected in a circuit to measure electric current?\ (a) Parallel to the component\ (b) **Series with the component**\ (c) Across the battery\ (d) Does not need to be connected, just held nearby\ Electric Potential and Potential Difference\ \ What provides the energy to maintain an electric current in a circuit?\ (a) Resistor\ (b) Ammeter\ (c) **Cell or battery**\ (d) Connecting wires\ What is the SI unit of electric potential difference?\ (a) Ampere\ (b) Coulomb\ (c) **Volt**\ (d) Ohm\ How is a voltmeter connected in a circuit?\ (a) In series with the component\ (b) **In parallel across the points where potential difference is to be measured**\ (c) Across the ammeter\ (d) Anywhere in the circuit\ Ohm\'s Law\ \ What is the relationship between potential difference (V) and current (I) across a conductor according to Ohm\'s Law?\ (a**) V is directly proportional to I (V ∝ I)**\ (b) V is inversely proportional to I (V ∝ 1/I)\ (c) V is proportional to the square of I (V ∝ I²)\ (d) There is no relationship between V and I\ What is the quantity that represents the opposition to the flow of current through a conductor?\ (a) Voltage\ (b) Current\ **(c) Resistance**\ (d) Power\ What is the SI unit of resistance?\ (a) Ampere\ (b) Coulomb\ (c) Volt\ **(d) Ohm**\ Factors Affecting Resistance\ \ How does the resistance of a conductor vary with its length?\ **(a) Resistance increases with length.\ **(b) Resistance decreases with length.\ (c) Resistance is independent of length.\ (d) None of the above\ How does the resistance of a conductor vary with its area of cross-section?\ (a) Resistance increases with cross-sectional area.\ (b) **Resistance decreases with cross-sectional area**.\ (c) Resistance is independent of cross-sectional area.\ (d) None of the above.\ The resistivity of a material is a measure of:\ (a) Its ability to conduct electricity.\ (b**) Its ability to resist the flow of electricity.**\ (c) Its ability to store electrical energy.\ (d) None of the above\ Which of the following materials is the best conductor of electricity?\ **(a) Copper**\ (b) Silver\ (c) Aluminum\ (d) Tungsten\ Resistors in Series and Parallel\ \ When resistors are connected in series, the current flowing through each resistor is:\ (a) The same.\ (b) **Different.**\ (c) Zero.\ (d) Cannot be determined.\ When resistors are connected in parallel, the potential difference across each resistor is:\ (**a) The same.**\ (b) Different.\ (c) Zero.\ (d) Cannot be determined.\ The total resistance of two resistors connected in series is:\ (a) Less than the smaller resistance.\ (b) Greater than the larger resistance.\ (c) **Equal to the sum of their individual resistances.\ **(d) Equal to the difference between their individual resistances.\ The total resistance of two resistors connected in parallel is:\ (a) Less than the smaller resistance.\ (b) Greater than the larger resistance.\ (c) Equal to the sum of their individual resistances.\ (d) Equal to the product of their individual resistances. Heating Effect of Electric Current\ \ The heat produced in a conductor due to the flow of electric current is called:\ (a**) Joule heating**\ (b) Ohm\'s heating\ (c) Faraday\'s heating\ (d) None of the above\ What is the relationship between the heat produced (H) in a resistor, the current (I), the resistance (R), and the time (t) for which the current flows?\ (a) H is directly proportional to I, R, and t.\ (b) H is directly proportional to I² and t, and inversely proportional to R.\ (c) H is directly proportional to I² and R, and directly proportional to t.\ (d) H is inversely proportional to I², R, and t.\ What is the purpose of a fuse in an electrical circuit?\ (a) To increase the current flow\ **(b) To protect the circuit from excessive current**\ (c) To convert electrical energy to light\ (d) To store electrical energy\ What is the material commonly used in fuse wires?\ **(a) Copper**\ (b) Tungsten\ (c) Lead-tin alloy\ (d) Nichrome\ Electric Power\ \ Electric power is defined as:\ (a) The rate at which electrical energy is consumed or dissipated.\ (b) The amount of electrical energy stored in a device.\ (c) The opposition to the flow of electric current.\ (d) None of the above\ What is the SI unit of power?\ (a) Joule\ **(b) Watt**\ (c) Volt-ampere\ (d) Kilowatt-hour\ Which of the following equations represents electric power (P) in terms of potential difference (V) and current (I)?\ **(a) P = VI**\ (b) P = V/I\ (c) P = I/V\ (**d) P = V²I**\ What is the commercial unit of electrical energy?\ (a) Joule\ (b) Watt\ **(c) Kilowatt-hour\ **(d) Volt-ampere\ Numerical Problems\ \ A current of 2 A flows through a 10 Ω resistor. What is the potential difference across the resistor?\ (a) 5 V\ (b) 10 V\ **(c) 20 V**\ (d) 0.2 V\ A bulb is rated at 100 W and 220 V. What is the current flowing through it when it is connected to a 220 V supply?\ (a) 2.2 A\ **(b) 0.45 A**\ (c) 22 A\ (d) 4.5 A\ Calculate the equivalent resistance when a 4 Ω resistor and a 6 Ω resistor are connected in series.\ (a) 2.4 Ω\ **(b) 10 Ω**\ (c) 24 Ω\ (d) 0.42 Ω\ Calculate the equivalent resistance when a 2 Ω resistor and a 3 Ω resistor are connected in parallel.\ (a) 1.2 Ω\ (b) 5 Ω\ (c) 6 Ω\ **(d) 0.83 Ω**\ A wire of resistance R is cut into three equal pieces. What is the resistance of each piece?\ **(a) R/3**\ (b) 3R\ (c) R\ (d) R/9\ How much heat is generated when a current of 5 A flows through a resistor of 10 Ω for 1 minute?\ (a) 250 J\ (b) 1500 J\ **(b) 15000 J**\ (d) 50 J\ Conceptual Understanding\ \ Why is it dangerous to touch an electrical appliance with wet hands?\ (a) Wet hands increase the resistance of the circuit.\ (b) Wet hands decrease the resistance of the circuit.\ **(c) Water is a good conductor of electricity, increasing the risk of electric shock.**\ (d) Water is an insulator, preventing electric shock.\ Why are birds not electrocuted when they sit on high voltage power lines?\ (a) Their feet are good insulators.\ (b) **They are not part of a complete electric circuit.**\ (c) The voltage is too high for their small bodies.\ (d) They have a special adaptation to avoid electric shock.\ Why is it advisable to use electrical appliances with ISI mark?\ (a) They are cheaper.\ (b) They come in various colors.\ **(c) They meet safety standards and are less likely to cause harm.**\ (d) They are easily available.\ Two wires of the same length and material but different cross-sectional areas are connected to the same potential difference. Which wire will have a higher current flowing through it?\ (a) The wire with the larger cross-sectional area.\ **(b) The wire with the smaller cross-sectional area.**\ (c) Both wires will have the same current.\ (d) It depends on the type of material.\ A heater is rated at 1000 W, 220 V. If the voltage drops to 110 V, what will be the power consumed by the heater?\ (a) 1000 W (power remains the same)\ **(b) 500 W (power reduces to half)\ **(c) 250 W (power reduces to one-fourth)\ (d) 2000 W (power doubles)\ Why are alloys commonly used in electrical heating devices?\ (a) They have lower melting points than pure metals.\ **(b) They have higher resistivities than pure metals.**\ (c) They are cheaper than pure metals.\ (d) They are better conductors than pure metals.