arrow_backBack to Study Resources

Quiz Chapter 3: Electricity

10 questions · Form 5 Physics Bab 3: Electricity

10 questions · plays in fullscreen

Full Question List & Answer Key

Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.

1. Two resistors of resistance R and 2R are connected in PARALLEL across a DC voltage supply. How does the power dissipated in the 2R resistor compare to the R resistor?

  1. It is half as much.
  2. It is twice as much.
  3. It is four times as much.
  4. It is equal.
Show answer

Answer: A

In parallel, potential difference V is identical. Power P = V² / R. Therefore, P ∝ 1R. The 2R resistor dissipates half the power of the R resistor.

2. In a V against I graph obtained for a cell, the vertical y-intercept represents:

  1. The total external resistance
  2. The electromotive force (e.m.f.) of the cell
  3. The internal resistance of the cell
  4. The short-circuit current
Show answer

Answer: B

From V = E - Ir, when I = 0 (open circuit / y-intercept), V = E (the electromotive force).

3. Which change will DOUBLE the resistance of a cylindrical uniform copper wire?

  1. Doubling the radius of the wire
  2. Doubling the cross-sectional area of the wire
  3. Doubling the length of the wire
  4. Halving the length of the wire
Show answer

Answer: C

From R = ρ(lA), resistance R is directly proportional to length l. Doubling l doubles the resistance.

4. What is the unit of electrical resistivity ρ?

  1. Ω
  2. Ω m
  3. Ω m⁻¹
  4. W m⁻¹
Show answer

Answer: B

From R = ρ(lA), ρ = R × Al => Ω × m² / m = Ω m (ohm-meter).

5. Which factor causes the terminal potential difference across a battery to be LESS than its electromotive force (e.m.f.) during closed circuit operation?

  1. Resistivity of connecting copper wires
  2. Voltage drop across the internal resistance of the battery
  3. Atmospheric pressure surrounding the circuit
  4. The capacity of the external load resistor
Show answer

Answer: B

When current I flows, a potential drop ('lost volts' = Ir) occurs across the internal resistance r of the battery, causing V = E - Ir.

6. An air conditioner rated at 1.5 kW is operated for 8 hours daily. How many units (kWh) of electricity are consumed by the appliance in a 30-day month?

  1. 360 kWh
  2. 12 kWh
  3. 36 kWh
  4. 120 kWh
Show answer

Answer: A

Energy = Power (kW) × time (hours) = 1.5 kW × (8 h/day × 30 days) = 1.5 kW × 240 h = 360 kWh.

7. A current of 2.5 A flows through a bulb for 4 minutes. What total electric charge passes through the bulb?

  1. 10 C
  2. 600 C
  3. 100 C
  4. 1000 C
Show answer

Answer: B

Q = I × t = 2.5 A × (4 × 60 s) = 2.5 A × 240 s = 600 C.

8. An open circuit voltmeter connected across a dry cell reads 1.5 V. When a 2.5 Ω resistor is connected across the cell, the voltmeter reading drops to 1.25 V. What is the internal resistance r of the cell?

  1. 0.5 Ω
  2. 0.25 Ω
  3. 1.0 Ω
  4. 2.0 Ω
Show answer

Answer: A

e.m.f. E = 1.5 V, V = 1.25 V. Current I = VR = 1.252.5 = 0.5 A. Lost volts Ir = E - V => 0.5 r = 1.5 - 1.25 = 0.25 => r = 0.5 Ω.

9. Two resistors of resistance R and 2R are connected in SERIES across a power supply. How does the power dissipated in the 2R resistor compare to the R resistor?

  1. It is half as much.
  2. It is twice as much.
  3. It is four times as much.
  4. It is equal.
Show answer

Answer: B

In series, current I is identical. Power P = I²R. Therefore, P ∝ R. The 2R resistor dissipates twice the power of the R resistor.

10. Superconductors are unique materials that exhibit:

  1. Infinite resistance at room temperature
  2. Zero electrical resistance below a critical transition temperature (Tc)
  3. Zero potential difference regardless of current
  4. Constant current output under changing magnetic fields
Show answer

Answer: B

Superconductors lose all electrical resistance (R = 0) when cooled below their specific critical temperature (Tc).

Sponsored