Lesson 3.7.3.1

3.7.3.1 Coulomb's law Quiz: AQA Physics, Unit 7

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.7.3.1, Coulomb's law: 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. Coulomb's law gives the force between two point charges in a vacuum as:

    • F = Q1 Q2 r^2 / (4 pi eps0)
    • F = Q1 Q2 / (4 pi eps0 r^2)
    • F = Q1 Q2 / (4 pi eps0 r)
    • F = 4 pi eps0 Q1 Q2 / r^2

  2. The permittivity of free space, eps0, has a value of approximately:

    • 9.11 x 10^-31 kg
    • 1.60 x 10^-19 C
    • 8.85 x 10^-12 F m^-1
    • 6.67 x 10^-11 N m^2 kg^-2

  3. What effect do two like electric charges have on each other?

    • No force acts
    • They oscillate
    • They attract
    • They repel

  4. Unlike gravitational forces, electrostatic forces between charges can be:

    • Attractive only
    • Zero always
    • Repulsive or attractive
    • Repulsive only

  5. In Coulomb's law, electrostatic force is inversely proportional to what quantity?

    • Separation
    • Square root separation
    • Separation squared
    • Charge product

  6. Where is charge considered to be concentrated for a uniformly charged sphere?

    • On its surface
    • At infinity
    • At its edge
    • At its centre

  7. Why can air be treated as a vacuum when calculating electrostatic forces?

    • Relative permittivity ~ 100
    • Relative permittivity ~ 1
    • Relative permittivity ~ 0
    • Relative permittivity ~ 80

  8. Two point charges of 2.0 microcoulomb and 3.0 microcoulomb are 0.10 m apart in a vacuum. What is the force between them?

    • 54 N
    • 0.54 N
    • 5.4 N
    • 0.0054 N

  9. What is the electrostatic force between an electron and a proton separated by 5.3 x 10^-11 m? Take e = 1.6 x 10^-19 C.

    • about 2.3 x 10^-28 N
    • about 8.2 x 10^-6 N
    • about 8.2 x 10^-10 N
    • about 8.2 x 10^-8 N

  10. The ratio of electrostatic to gravitational force between an electron and a proton is roughly:

    • 10^-39
    • 10^3
    • 10^39
    • 10^12

  11. Two like point charges of 1.0 microcoulomb each are 1.0 m apart in a vacuum. What is the force between them?

    • 9 x 10^3 N
    • 9 x 10^-3 N
    • 9 x 10^-6 N
    • 9 x 10^-9 N

  12. What is the net electrostatic force on a charge placed midway between identical positive charges?

    • Infinite force
    • Zero
    • Double single force
    • Half single force

  13. A charge Q1 and charge Q2 are separated by r and experience force F. If Q1 is doubled and r is halved, the new force is:

    • 2F
    • 4F
    • F/8
    • 8F

  14. How do electrostatic forces exerted on each other by two point charges compare?

    • Equal and opposite
    • Equal same direction
    • Unrelated in magnitude
    • Proportional to charge

  15. The constant 1 / (4 pi eps0) in Coulomb's law is approximately:

    • 9.0 x 10^9 N m^2 C^-2
    • 1.60 x 10^-19 N m^2 C^-2
    • 8.85 x 10^-12 N m^2 C^-2
    • 6.67 x 10^-11 N m^2 kg^-2

  16. When the separation between two point charges is tripled, the electrostatic force becomes:

    • one sixth
    • one third
    • one twelfth
    • one ninth

  17. Charges of +4.0 µC and +1.0 µC are 0.30 m apart. Where is the net force zero?

    • 0.15 m from +4.0 µC
    • 0.25 m from +4.0 µC
    • 0.10 m from +4.0 µC
    • 0.20 m from +4.0 µC

  18. Two protons are separated by 1.0 x 10^-15 m. Estimate the electrostatic force between them, with e = 1.6 x 10^-19 C.

    • about 2300 N
    • about 2.3 N
    • about 230 N
    • about 0.23 N

  19. Compared to the gravitational force between two electrons, their electrostatic force is:

    • Zero
    • Much stronger
    • Equal in magnitude
    • Much weaker

  20. An electron orbits a proton in a circle of radius 5.3 x 10^-11 m, with the electrostatic force providing the centripetal force. Estimate its speed (m_e = 9.11 x 10^-31 kg).

    • about 1.1 x 10^3 m s^-1
    • about 4.4 x 10^6 m s^-1
    • about 2.2 x 10^4 m s^-1
    • about 2.2 x 10^6 m s^-1

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