Physics Chapter: Electric Charge and Current

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Questions and Answers

What is the S.I. unit of electric charge?

Ohm

Volt

Ampere

Coulomb (correct)

What does Ohm's law express?

The relationship between current, voltage, and resistance (correct)

The quantization of electric charge

The power of electric circuits

The conservation of electric charge

Which property indicates that charge cannot be created or destroyed?

Invariance of Charge

Quantization of Charge

Charge Conservation (correct)

Additivity of Charge

In the context of electric current, what does 1 Ampere represent?

1 Coulomb per second (D) Signup and view all the answers

What is the unit of electric potential difference?

Volt (D) Signup and view all the answers

What type of materials allow electric current to pass through easily?

Conductors (D) Signup and view all the answers

What is the formula to calculate electric power?

P = I^2R (A) Signup and view all the answers

The relationship Q = ne demonstrates what property of charge?

Quantization of Charge (A) Signup and view all the answers

What is the primary function of a voltmeter in an electric circuit?

Measures electric potential difference (C) Signup and view all the answers

Which of the following is NOT a characteristic of electric charge?

Charge can be created (B) Signup and view all the answers

What is the formula used to calculate voltage in terms of work and charge?

V = W/Q (B) Signup and view all the answers

Which of the following correctly describes Ohm's Law?

V ∝ I at constant temperature (B) Signup and view all the answers

Which factor does NOT affect the resistance of a conductor?

Type of electric source used (D) Signup and view all the answers

If the area of cross-section of a conductor is doubled, what happens to the resistance?

Resistance is halved (C) Signup and view all the answers

What is the unit of resistance?

Ohm (Ω) (C) Signup and view all the answers

Which equation correctly defines current?

I = Q/t (D) Signup and view all the answers

What property defines the intrinsic ability of a material to resist the flow of electric current?

Resistivity (A) Signup and view all the answers

In an electric circuit, what is the purpose of an ammeter?

To measure current (D) Signup and view all the answers

If the length of a conductor is tripled, how does the resistance change?

Resistance increases threefold (C) Signup and view all the answers

During a circuit analysis, you need to find the charge Q. Which formula would you use?

Q = ne (D) Signup and view all the answers

What is the formula used to express the relationship between voltage, current, and resistance?

V = IR (C) Signup and view all the answers

Which unit is commonly used to measure electric power?

Watt (W) (D) Signup and view all the answers

What happens to an electric fuse when the current rises suddenly?

It melts and breaks the circuit. (C) Signup and view all the answers

How is electric energy measured when consumed for one hour?

Kilowatt-hour (kWh) (D) Signup and view all the answers

What determines the heat produced in a resistor when current flows through it?

The resistance of the resistor and the current. (B) Signup and view all the answers

What is the relationship between power and time in calculating energy?

Energy = Power × Time (A) Signup and view all the answers

Which of these statements correctly describes an electric heater?

It uses a nichrome coil with high resistance. (C) Signup and view all the answers

What is the effect of incorrect units when applying Ohm’s Law?

It will lead to incorrect results. (A) Signup and view all the answers

If the power of a device is 1000 watts and it operates for 2 hours, how much energy is consumed?

2 kWh (A) Signup and view all the answers

What is the primary function of an electric fuse in a circuit?

To prevent excess current from damaging equipment. (D) Signup and view all the answers

In a series circuit, how does the total current behave compared to individual resistors?

It remains constant through all resistors. (C) Signup and view all the answers

What characteristic defines the current flow in a parallel circuit?

Current divides inversely proportional to resistance. (A) Signup and view all the answers

Which formula represents the total resistance in a series circuit?

$R_t = R_1 + R_2$ (D) Signup and view all the answers

How is the voltage divided across resistors in a series circuit?

It divides based on the resistance values. (B) Signup and view all the answers

What is the relationship between heat and current in Joule's Law?

Heat is proportional to the square of the current. (B) Signup and view all the answers

What determines the power input to an electric circuit?

Current multiplied by voltage. (D) Signup and view all the answers

How is the total current through a resistor calculated in a series circuit?

$I = V/R$ (A) Signup and view all the answers

What is the first step in analyzing a circuit for mixed connections?

Simplify the circuit by identifying series and parallel combinations. (A) Signup and view all the answers

What happens to the current flowing through bulbs in a parallel circuit?

It is the same as the total circuit current. (C) Signup and view all the answers

In a series circuit, what happens to the total voltage as additional resistors are added?

It increases with each added resistor. (C) Signup and view all the answers

Study Notes

Electricity Revision Notes

Electric Charge: A physical property of matter causing it to experience force in an electromagnetic field.
- SI unit: Coulomb (C)
- Positive charge: Loss of electrons
- Negative charge: Gain of electrons
- Properties:
  - Additivity: Total charge is the sum of all charges
  - Conservation: Charge cannot be created or destroyed
  - Invariance: Charge value is constant regardless of speed
  - Quantization: Charge is a multiple of electron charge (Q = ne, where e = 1.6 x 10⁻¹⁹ C)

Electric Current

Flow of electric charge through a conductor.
- Unit: Ampere (A) (1 A = 1 C/s)
- I = Q/t (I = current, Q = charge, t = time)
- Measuring Instruments:
  - Ammeter: Measures current intensity
  - Milliammeter: Measures small currents
  - Galvanometer: Detects and measures tiny currents
  - Voltmeter: Measures potential difference

Potential Difference

Work done to move a unit positive charge between two points.
- Unit: Volt (V) (1 V = 1 J/C)
- V = W/Q (V = potential difference, W = work done, Q = charge)

Ohm's Law

Current through a conductor is directly proportional to the potential difference across its ends, at a constant temperature.
- V = IR (V = voltage, I = current, R = resistance)
- Resistance: Property of a conductor resisting charge flow -Unit: Ohm (Ω)
  - Factors affecting resistance:
    - Length (R ∝ l): Resistance increases with length
    - Area (R ∝ 1/A): Resistance decreases with area
    - Material: Factors like resistivity (ρ) differ based on the material
    - R = ρL/A (ρ = resistivity, L = length, A = area)
    - p= RA/L

Electric Circuit

Continuous path for current flow (power source, conductor, load)
- Components and symbols
- Series and parallel circuits
- Circuit analysis & calculations

Heating Effect of Electric Current

Heat is proportional to the square of current, resistance, and time.
- H = I²Rt or H = VIt
- Power (P) : Rate of energy consumption; P = VI or P = I²R or P= V²/R

Electric Power and Energy

Power: Rate of energy consumption (Unit: Watt (W), 1 W = 1 J/s)
Electric Energy: Energy used to allow current flow (watt hours or kWh)

Numerical Problems Solving Steps

Identify given values and the quantity to find
Utilize Ohm's Law (V = IR) for finding unknown values.
Ensure units are consistent
Use appropriate formula for heat (H=I²Rt or H=VIt) or power (P=VI or P=I²R or P=V²/R)

Circuit Types

Series Circuit:
- Current is the same throughout
- Voltage is divided across resistors
- Total resistance is the sum of individual resistances
Parallel Circuit:
- Voltage is the same across all resistors
- Current is divided inversely proportional to resistance
- Reciprocal of total resistance is the sum of reciprocals of individual resistances
Mixed Circuit: A combination of series and parallel circuits; simplify the circuit for calculations.

Additional Question Types

Understanding how changing a component in a circuit (like resistance) affects other components (current, voltage, etc.) for different circuit types (series, parallel, and mixed)

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Description

Test your understanding of electric charge, current, and related concepts with this quiz. Questions cover foundational principles such as Ohm's Law, electric resistance, and the properties of materials. Perfect for students looking to reinforce their knowledge in physics.