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What is the charge of a proton?
What is the charge of a proton?
A neutral atom has an unequal number of protons and electrons.
A neutral atom has an unequal number of protons and electrons.
False
What happens to a body when it loses electrons?
What happens to a body when it loses electrons?
It becomes positively charged.
Charge is measured in __________.
Charge is measured in __________.
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What are the larger units of charge equivalent to 1 Coulomb?
What are the larger units of charge equivalent to 1 Coulomb?
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Match the following terms with their definitions:
Match the following terms with their definitions:
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Electric charge exists in arbitrary amounts rather than discrete units.
Electric charge exists in arbitrary amounts rather than discrete units.
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What is the smallest unit of electric charge?
What is the smallest unit of electric charge?
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What is the direction of conventional current flow in a circuit?
What is the direction of conventional current flow in a circuit?
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Electrons accumulate at the positive terminal of a battery.
Electrons accumulate at the positive terminal of a battery.
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What formula is used to calculate voltage?
What formula is used to calculate voltage?
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One volt represents ____ Joule of work done on one Coulomb of charge.
One volt represents ____ Joule of work done on one Coulomb of charge.
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Match the following components of an electric circuit with their functions:
Match the following components of an electric circuit with their functions:
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What happens to a battery when the reactants are completely converted to products?
What happens to a battery when the reactants are completely converted to products?
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Ohm's Law states that current is inversely proportional to voltage.
Ohm's Law states that current is inversely proportional to voltage.
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What is the SI unit of resistance?
What is the SI unit of resistance?
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A rheostat allows for the ____ adjustment of resistance.
A rheostat allows for the ____ adjustment of resistance.
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Which device is used to control the flow of current in a circuit?
Which device is used to control the flow of current in a circuit?
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The potential difference can exist even if no current is flowing through the circuit.
The potential difference can exist even if no current is flowing through the circuit.
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What is the main purpose of a voltmeter in a circuit?
What is the main purpose of a voltmeter in a circuit?
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The flow of current in a circuit is continuous and follows a ____ path.
The flow of current in a circuit is continuous and follows a ____ path.
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What does the slope of the V-I characteristic graph represent?
What does the slope of the V-I characteristic graph represent?
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Match each component to its corresponding symbol:
Match each component to its corresponding symbol:
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Study Notes
Introduction to Charge
- Charge is a fundamental property of matter that causes it to experience and produce electrical and magnetic effects.
- Charge is measured in Coulombs (C).
- Charge is present on all matter in the universe due to the presence of protons and electrons within atoms.
- Protons carry a positive charge while electrons carry a negative charge; neutrons are neutral particles that have no charge.
- The charge of a single proton is equal in magnitude to the charge of a single electron, but it's opposite in sign.
- The charge of a proton is +1.6 × 10⁻¹⁹ C and the charge of an electron is -1.6 × 10⁻¹⁹ C.
Charged Bodies
- A body appears charged when the balance of protons and electrons is disturbed.
- Losing electrons: When a body loses electrons, it becomes positively charged as the number of protons exceeds the number of electrons.
- Gaining electrons: When a body gains electrons, it becomes negatively charged as the number of electrons exceeds the number of protons.
- This is a simple concept that underlies many chemical reactions.
Quantization of Electric Charge
- The concept of quantization states that electric charge can only exist in discrete units.
- In other words, charge cannot be divided into any arbitrary amount.
- This is analogous to the idea that there are discrete energy levels in an atom.
- The smallest unit of charge is the charge of a single electron or proton, which is 1.602 x 10⁻¹⁹ C.
Other Key Facts
- Larger units of charge include the milli-Coulomb (mC) and the micro-Coulomb (µC).
- 1 mC = 10⁻³ C
- 1 µC = 10⁻⁶ C
- The number of protons and neutrons in an atom determines its atomic mass, while the number of protons determines the atomic number.
- The charge of an atom is neutral when it has an equal number of protons and electrons.
- The concept of a "neutral" object does not mean that it has no charge.
- It means that the positive and negative charges within the object are balanced.
Concept of Potential Difference & Voltage
- Potential Difference is described as voltage.
- Voltage is the force applied to electrons in conductors.
- Conductors are wire, typically made of metal, and contain free electrons which contribute to electric current.
What is Voltage?
- Voltage is the force that causes electric charges to flow.
- It's the external force acting on electrons to make them move.
- It is also known as Potential Difference.
How Voltage Works
- Potential Difference is created by a battery within a conductor circuit.
- A battery has two ends: a positive and a negative terminal.
- The positive terminal is at a higher potential while the negative terminal is at a lower potential.
- The negative terminal repels electrons in the conductor, and the positive terminal attracts them.
- This force causes electrons to flow.
- Conventional Current is the assumed direction of flow, from positive to negative.
- Electron flow is actually from negative to positive.
- Voltage is numerically represented by potential difference, for example, 2 volts means the high terminal is at 2 volts and the low terminal is at 0 volts.
The Source of Voltage
- The battery provides the potential difference.
- This is due to the chemical reaction in the battery, which creates a positive charge at the cathode and a negative charge at the anode.
Why Batteries Die
- Batteries contain reactants which undergo chemical reactions to produce products.
- The reactants eventually become depleted and are completely converted to products, causing the potential difference to deplete and current to stop flowing.
- This is when the battery is considered dead.
Electron Accumulation
- Electrons do not accumulate at the positive terminal, despite the constant flow, due to continuous redox reactions at cathode and anode.
- The battery continuously takes electrons in the circuit and releases them back into the circuit.
Analogy to Gravity
- Voltage can be understood using the analogy of water flow in a gravity-based system.
- When a tank of water is situated higher than another tank, the water flows from the higher tank to the lower tank due to a difference in potential energy.
- When the tanks are at the same level, the flow stops due to a lack of potential difference.
- The same applies to voltage. The flow continues when there is a potential difference.
Voltage Formula
- Voltage can be calculated with the formula: V = W / Q.
- Where V represents voltage, W represents work done, and Q represents charge.
- The units are Volts, Joules, and Coulombs, respectively.
- One Volt represents one Joule of work done on one Coulomb of charge.
Work Done
- The work done required to move two coulombs of charge across a potential difference of 12 volts is 24 joules.
Electric Circuits
- An electric circuit is a continuous and closed path made of wires through which electric current flows.
- The basic components of an electric circuit include: A battery (source of energy), Wires, A switch (on/off control), Appliances, Resistors, Measuring instruments like ammeter and voltmeter.
- An ammeter measures current in a circuit and is connected in series.
- A voltmeter measures voltage across a component and is connected in parallel.
Symbols Used in Circuit Diagrams
- A single electric cell is symbolized by short and long lines, representing negative and positive terminals, respectively.
- A battery or multiple cells are symbolized by multiple short and long lines.
- A switch, when open, represents a break in the circuit and no current flow. When closed, the switch allows current flow.
- A dot within the switch symbol represents a closed switch and current flowing through it.
- A wire joint is symbolized by a junction to show a single current dividing into multiple paths.
- Wires crossing without joining are symbolized by wires crossing with no junction to indicate no current transfer.
- A resistor is symbolized by a zig-zag line.
- A rheostat is symbolized by a wavy line indicating adjustable resistance.
- An ammeter is represented by the letter "A" inside a circle.
- A voltmeter is represented by the letter "V" inside a circle.
Electric Circuit Elements
- A battery eliminator provides a voltage source and converts alternating current (AC) to direct current (DC) for use in labs.
- A resistor box offers fixed resistance, while a rheostat allows variable resistance adjustment.
- Ammeters measure current flow and voltmeters measure voltage difference across components.
- Connecting wires connect different components in a circuit.
- On/off switches control current flow within a circuit.
Ammeter vs Voltmeter
- An ammeter measures electric current and is connected in series, with a very low resistance.
- A voltmeter measures voltage and is connected in parallel, with a very high resistance.
Ohm's Law
- Ohm's Law states that the current flowing through a conductor is directly proportional to the potential difference applied across its ends at a constant temperature.
- This means that an increase in voltage leads to an increase in current, and vice versa.
- Mathematically, Ohm's Law is represented by the formula: V=IR, where V is voltage, I is current, and R is resistance.
- R, resistance, is a constant in this equation but is not a universal constant. It can vary depending on other factors.
Resistance
- Resistance is the opposition offered by atoms in a conductor against the flow of current (electron flow).
- The opposition arises from collisions between moving electrons and stationary atoms within the conductor.
- These collisions generate heat, causing the conductor to warm, which is why electrical appliances get hot.
- Resistance is denoted by 'R' and its SI unit is the ohm (Ω).
Voltage-Current (VI) Characteristic Graph
- The VI characteristic graph, a visual representation of Ohm's Law, confirms the direct proportionality between voltage and current.
- It is a straight line graph, demonstrating the linear relationship between V and I.
- The slope of the V-I graph represents the resistance (R = ΔV/ΔI).
- Conversely, if the I-V graph is plotted, the slope represents 1/R.
- The steeper the slope, the greater the resistance.
- If the graph curves, it indicates that Ohm's Law is not being followed.
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Description
This quiz provides an overview of the concept of charge in physics. Learn about the properties of protons and electrons, their charges, and how bodies become charged through the loss or gain of electrons. Test your understanding of this fundamental topic in electrical and magnetic effects.
