Lesson 7.3.1

7.3.1 Capacitance and energy stored in a capacitor Quiz: Pearson Edexcel Physics, Unit 7

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 7.3.1, Capacitance and energy stored in a capacitor: 20 multiple choice questions for the Pearson Edexcel Physics (9PH0), Unit 7: Electric and Magnetic Fields, written with Revision Ninja.

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The 20 questions

  1. How is capacitance defined?

    • The current flowing per unit time through the capacitor
    • The charge stored per unit potential difference across the capacitor
    • The energy stored per unit charge on the capacitor
    • The potential difference per unit charge stored on the capacitor

  2. What is the SI unit of capacitance?

    • The farad, equivalent to C V^-1
    • The ohm, equivalent to V A^-1
    • The henry, equivalent to V s A^-1
    • The tesla, equivalent to N A^-1 m^-1

  3. Which expression gives the energy stored in a capacitor of capacitance C when the potential difference across it is V?

    • W = (1/2) C V^2
    • W = C V / 2
    • W = C V^2
    • W = 2 C V^2

  4. The area under a graph of potential difference against charge stored on a capacitor represents what?

    • The energy stored by the capacitor
    • The current through the capacitor
    • The capacitance of the capacitor
    • The power dissipated in the capacitor

  5. For a capacitor of fixed capacitance, what shape is the graph of potential difference V against charge Q?

    • A straight line through the origin with gradient 1/C
    • A curve passing through the origin and rising with increasing gradient
    • A horizontal line at a constant potential difference
    • A straight line through the origin with gradient C

  6. A 100 microfarad capacitor is charged to 12 V. What charge is stored on it?

    • 1.2 x 10^-5 C
    • 1.2 x 10^-3 C
    • 8.3 x 10^-6 C
    • 0.12 C

  7. A 4.7 millifarad capacitor is charged to 9.0 V. How much energy is stored?

    • 0.19 J
    • 1.9 J
    • 0.38 J
    • 0.042 J

  8. A 2.0 microfarad capacitor is charged to 200 V. What energy is stored in it?

    • 0.00020 J
    • 0.40 J
    • 0.040 J
    • 0.020 J

  9. A capacitor stores 0.50 J of energy when the potential difference across it is 10 V. What is its capacitance?

    • 5.0 mF
    • 10 mF
    • 0.10 F
    • 20 mF

  10. A capacitor stores 3.0 millicoulomb of charge at a potential difference of 6.0 V. How much energy is stored?

    • 2.0 x 10^-3 J
    • 9.0 x 10^-3 J
    • 4.5 x 10^-3 J
    • 1.8 x 10^-2 J

  11. The potential difference across a fixed capacitor is doubled. By what factor does the energy stored change?

    • It is unchanged
    • It becomes four times larger
    • It becomes twice as large
    • It becomes half as large

  12. A 470 microfarad capacitor stores 0.40 J of energy. What is the potential difference across it?

    • 0.85 V
    • 41 V
    • 0.0017 V
    • 1700 V

  13. A capacitor is charged so that its V against Q graph passes through the point (2.0 mC, 10 V). What is the energy stored?

    • 0.020 J
    • 0.20 J
    • 0.0050 J
    • 0.010 J

  14. A capacitor of fixed capacitance has its potential difference doubled. What happens to the charge stored on it?

    • It doubles
    • It halves
    • It quadruples
    • It is unchanged

  15. A 5.0 microfarad capacitor stores 2.5 millijoule of energy. What charge is stored on it?

    • 6.3 x 10^-4 C
    • 1.6 x 10^-4 C
    • 1.6 x 10^-3 C
    • 3.2 x 10^-4 C

  16. A 1.0 microfarad capacitor is charged to 10 V and then the potential difference across it is reduced to 6.0 V. How much energy is lost from the capacitor?

    • 3.2 x 10^-5 J
    • 1.8 x 10^-5 J
    • 5.0 x 10^-5 J
    • 6.8 x 10^-5 J

  17. A 4.0 microfarad capacitor and a separate 2.0 microfarad capacitor are each charged to 10 V. What is the total energy stored in both?

    • 1.5 x 10^-4 J
    • 2.0 x 10^-4 J
    • 3.0 x 10^-4 J
    • 6.0 x 10^-4 J

  18. Why is the energy stored in a capacitor charged from zero equal to (1/2) QV rather than QV?

    • Charging releases energy into the surroundings as light and sound
    • The capacitor stores energy only in one of its two plates during charging
    • Half of the charge is lost as heat in the connecting wires during charging
    • The potential difference rises linearly from zero as charge builds up, so the average potential difference during charging is V/2

  19. Which statement about the energy stored in a capacitor is correct?

    • It depends only on the capacitance and not on the potential difference across it
    • It is always equal to the charge multiplied by the capacitance, regardless of voltage
    • It depends on both capacitance and potential difference, so a higher voltage stores more energy
    • It depends only on the charge and is independent of the capacitance chosen

  20. A capacitor stores 6.0 millicoulomb of charge at a potential difference of 3.0 V. What is its capacitance?

    • 2.0 mF
    • 0.50 mF
    • 0.20 F
    • 18 mF

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