Lesson 7.1.2

7.1.2 Coulomb's law and the field of a point charge Quiz: Pearson Edexcel Physics, Unit 7

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 7.1.2, Coulomb's law and the field of a point charge: 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. What does Coulomb's law state about the force between two point charges?

    • The force is proportional to the sum of the charges and inversely proportional to their separation
    • The force is independent of the charges and inversely proportional to the separation
    • The force is proportional to the product of the charges and inversely proportional to the square of their separation
    • The force is proportional to the square of each charge and directly proportional to their separation

  2. Which expression gives the Coulomb's law constant k in terms of the permittivity of free space epsilon0?

    • k = 4 pi epsilon0
    • k = 1 / (4 pi epsilon0)
    • k = 1 / (2 pi epsilon0)
    • k = epsilon0 / (4 pi)

  3. Two like point charges are placed near each other. What is the direction of the electrostatic force between them?

    • Repulsive, pushing the charges apart
    • Zero, because like charges cannot exert any force
    • Attractive, pulling the charges together
    • Perpendicular to the line joining the charges

  4. How does the electric field strength of a point charge vary with distance r from the charge?

    • It is inversely proportional to the distance
    • It is independent of the distance from the charge
    • It is directly proportional to the square of the distance
    • It is inversely proportional to the square of the distance

  5. Which equation gives the electric field strength due to a point charge Q at distance r from it?

    • E = Q r^2 / (4 pi epsilon0)
    • E = Q / (4 pi epsilon0 r^2)
    • E = Q / (4 pi epsilon0 r)
    • E = 4 pi epsilon0 Q / r^2

  6. Two point charges of +2.0 microcoulomb and +3.0 microcoulomb are 0.30 m apart. What is the magnitude of the force between them?

    • 0.054 N, repulsive
    • 6.0 N, repulsive
    • 0.20 N, attractive
    • 0.60 N, repulsive

  7. A +4.0 nC charge and a -2.0 nC charge are 0.20 m apart. What is the magnitude and nature of the force between them?

    • 1.8 x 10^-4 N, repulsive
    • 3.6 x 10^-6 N, attractive
    • 9.0 x 10^-7 N, repulsive
    • 1.8 x 10^-6 N, attractive

  8. If the separation between two point charges is doubled, by what factor does the electrostatic force change?

    • It becomes four times its original value
    • It becomes twice its original value
    • It becomes one quarter of its original value
    • It becomes one half of its original value

  9. What is the electric field strength at a point 0.50 m from a point charge of +2.0 microcoulomb?

    • 2.9 x 10^5 N C^-1
    • 7.2 x 10^4 N C^-1
    • 3.6 x 10^4 N C^-1
    • 1.8 x 10^4 N C^-1

  10. What is the electric field at a point 0.20 m from a point charge of -5.0 microcoulomb?

    • 1.1 x 10^6 N C^-1, directed away from the charge
    • 2.3 x 10^5 N C^-1, directed towards the charge
    • 1.1 x 10^6 N C^-1, directed towards the charge
    • 5.6 x 10^5 N C^-1, directed away from the charge

  11. Two equal positive point charges are placed a fixed distance apart. Where is the resultant electric field zero?

    • At a point on the perpendicular bisector far from both charges
    • At a point very far from both charges on the line joining them
    • At the position of either charge on the line joining them
    • At the midpoint on the line joining the charges

  12. What is the magnitude and nature of the electrostatic force between an electron and a proton separated by 5.3 x 10^-11 m?

    • 1.6 x 10^-19 N, repulsive
    • 8.2 x 10^-9 N, repulsive
    • 8.2 x 10^-8 N, attractive
    • 2.6 x 10^-7 N, attractive

  13. A negative point charge is placed near a fixed positive point charge. In which direction does the force on the negative charge act?

    • Perpendicular to the line joining the two charges
    • Towards the positive charge, because opposite charges attract
    • Away from the positive charge, because opposite charges repel
    • The force is zero because the charges have different signs

  14. Point charges of +3.0 microcoulomb and -3.0 microcoulomb are 0.60 m apart on a line. What is the resultant electric field at the midpoint between them?

    • 6.0 x 10^5 N C^-1, directed from the positive charge towards the negative charge
    • Zero, because the two charges are equal and opposite
    • 3.0 x 10^5 N C^-1, directed from the positive charge towards the negative charge
    • 6.0 x 10^5 N C^-1, directed from the negative charge towards the positive charge

  15. The electric force between an electron and a proton is compared with the gravitational force between them at the same separation. Approximately what is the ratio of the electric force to the gravitational force?

    • 2.3 x 10^39
    • 2.3 x 10^42
    • 1.2 x 10^10
    • 2.3 x 10^36

  16. The electric field strength at 2.0 m from a point charge is 4.5 x 10^3 N C^-1. What is the magnitude of the charge?

    • 2.0 microcoulomb
    • 8.0 microcoulomb
    • 0.50 microcoulomb
    • 18 microcoulomb

  17. Charges +q and +4q are separated by distance d. Where between them is the resultant electric field zero?

    • At one third of the separation from the charge +4q
    • At the midpoint between the two charges
    • Outside the pair, at a distance d from the charge +q
    • At one third of the separation from the charge +q

  18. An electron orbits a proton in a circular path of radius 5.3 x 10^-11 m, with the Coulomb force providing the centripetal force. What is the orbital speed of the electron?

    • 2.2 x 10^6 m s^-1
    • 1.1 x 10^6 m s^-1
    • 4.4 x 10^6 m s^-1
    • 9.1 x 10^5 m s^-1

  19. Which statement about the electric field of a point charge is correct?

    • The field increases with distance from the charge, in proportion to the distance
    • The field is uniform at all distances from the charge and does not depend on distance
    • The field is zero at all distances except exactly at the position of the charge
    • The field is strongest close to the charge and falls rapidly with increasing distance

  20. A student claims Coulomb's law can be applied to any two charged objects at any separation, regardless of their size or shape. Which response is correct?

    • The student is wrong because Coulomb's law applies only to electrons and protons
    • The student is right, but only if the objects are made of metal
    • The student is wrong: the simple point-charge form applies to point charges, or spherical charges treated as point charges at their centres
    • The student is right: Coulomb's law applies to any charged objects at any separation

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