Lesson 3.7.4.1

3.7.4.1 Capacitance Quiz: AQA Physics, Unit 7

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.7.4.1, Capacitance: 20 multiple choice questions for the AQA Physics (7408), Unit 7: Fields and their consequences (A-level only), written with Revision Ninja.

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The 20 questions

  1. Which expression defines the capacitance C of a capacitor?

    • C = V/Q, where Q is the charge on one plate and V is the pd between the plates
    • C = QV, where Q is the charge on one plate and V is the pd between the plates
    • C = Q/V, where Q is the charge on one plate and V is the pd between the plates
    • C = Q/I, where Q is the charge on one plate and I is the current through the plates

  2. What is the SI unit of capacitance?

    • farad (F), equivalent to coulomb per volt (C V^-1)
    • tesla (T), equivalent to newton per ampere metre (N A^-1 m^-1)
    • ohm (ohm), equivalent to volt per ampere (V A^-1)
    • henry (H), equivalent to volt second per ampere (V s A^-1)

  3. A 4.7 mF capacitor is charged to 12 V. What charge is stored on it?

    • 0.056 C
    • 0.0039 C
    • 0.39 C
    • 2.6 C

  4. The pd across a capacitor is doubled while its plate geometry and dielectric stay the same. What happens to its capacitance?

    • It doubles, because capacitance is directly proportional to the pd across it
    • It halves, because capacitance is inversely proportional to the pd across it
    • It quadruples, because capacitance is proportional to the square of the pd across it
    • It stays the same, because capacitance depends only on the geometry and the dielectric

  5. A capacitor stores 2.0 mC of charge when the pd across it is 400 V. What is its capacitance?

    • 8.0 millifarad
    • 5.0 microfarad
    • 0.20 microfarad
    • 50 microfarad

  6. On a graph of charge Q against potential difference V for a capacitor, what does the gradient represent?

    • The energy stored per unit charge on the plates
    • The resistance of the circuit connected to the capacitor
    • The capacitance of the capacitor
    • The current flowing into the capacitor

  7. A 220 microfarad capacitor is connected to a 9.0 V supply. Roughly what charge is delivered to it?

    • about 0.024 mC
    • about 0.20 mC
    • about 24 mC
    • about 2.0 mC

  8. Which statement about the charges on a charged capacitor is correct?

    • The two plates carry equal and opposite charges, so the net charge on the capacitor is zero
    • Only the positive plate carries charge, while the negative plate remains neutral
    • The charge is spread uniformly through the dielectric between the two plates
    • Both plates carry the same positive charge, giving a large net charge on the capacitor

  9. A capacitor of capacitance 10 microfarad is charged. How much charge is needed to raise its pd from 0 V to 5.0 V?

    • 2.0 x 10^-4 C
    • 2.0 x 10^-6 C
    • 5.0 x 10^-6 C
    • 5.0 x 10^-5 C

  10. A capacitor holds 3.0 microcoulomb of charge at a pd of 6.0 V. What is its capacitance?

    • 0.5 millifarad
    • 0.5 microfarad
    • 18 microfarad
    • 2.0 microfarad

  11. Which change would increase the capacitance of a parallel-plate capacitor?

    • Moving the plates closer together
    • Reducing the area of the plates
    • Increasing the pd applied across the plates
    • Removing the charge stored on the plates

  12. A 1.0 F capacitor is charged to 1.0 V. How much charge does it store?

    • 1.0 C
    • 0.5 C
    • 1.0 mC
    • 10 C

  13. Which quantity equals the charge on a capacitor divided by its capacitance?

    • The energy stored in the capacitor
    • The electric field strength between the plates
    • The current flowing into the capacitor
    • The potential difference across the capacitor

  14. A 47 microfarad capacitor carries 0.94 mC. Its charge is then raised to 1.88 mC. What is the new pd?

    • 10 V
    • 80 V
    • 40 V
    • 20 V

  15. A capacitor is kept connected to a battery while its plates are pulled apart so the separation doubles. The battery pd stays fixed. What happens to the charge on the plates?

    • It quadruples, since the field between the plates doubles
    • It halves, since capacitance halves and the pd is fixed
    • It stays the same, since the battery fixes the charge
    • It doubles, since capacitance doubles and the pd is fixed

  16. A 2200 microfarad and a 470 microfarad capacitor each store 0.10 C. Which statement is correct?

    • The 470 microfarad capacitor has the higher pd, about 213 V, and the 2200 microfarad one about 45 V
    • The 2200 microfarad capacitor has the higher pd, about 213 V, and the 470 microfarad one about 45 V
    • Both capacitors have the same pd, of about 0.10 V
    • The 470 microfarad capacitor has the higher pd, about 45 V, and the 2200 microfarad one about 213 V

  17. The pd across a 2.5 microfarad capacitor is raised from 3.0 V to 9.0 V. How much extra charge is stored?

    • 15 microcoulomb
    • 3.3 microcoulomb
    • 30 microcoulomb
    • 1.5 microcoulomb

  18. A capacitor with capacitance C is charged and then disconnected from the supply. Its plates are moved apart so the pd doubles. What is the new capacitance?

    • C/4, since the pd has doubled twice
    • C/2, half the original, since C = Q/V and Q is fixed
    • C, unchanged, since capacitance is fixed by the plates
    • 2C, since the pd has doubled

  19. The charge on a capacitor is increased by 50% while its capacitance stays constant. By what factor does its pd change?

    • 2.25 times
    • 2.0 times
    • 1.5 times
    • 0.67 times

  20. A 33 microfarad capacitor holds 6.6 mC of charge. What is the pd across it?

    • 20 V
    • 2000 V
    • 0.005 V
    • 200 V

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