Lesson 7.2.1

7.2.1 Electric potential, field lines and equipotentials Quiz: Pearson Edexcel Physics, Unit 7

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 7.2.1, Electric potential, field lines and equipotentials: 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 the electric potential at a point defined?

    • The work done per unit positive charge in bringing a small positive charge from infinity to that point
    • The energy stored per unit volume of the electric field at that point
    • The force per unit positive charge acting at that point in the field
    • The work done per unit time in moving a charge through a conductor

  2. What is the SI unit of electric potential?

    • The farad, equivalent to C V^-1
    • The newton per coulomb, equivalent to N C
    • The coulomb per second, equivalent to A
    • The volt, equivalent to J C^-1

  3. What is the electric potential at a distance r from a point charge Q in a vacuum?

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

  4. What is the relationship between the direction of electric field lines and equipotential lines or surfaces?

    • Field lines are perpendicular to equipotential surfaces at every point
    • Field lines are at 45 degrees to equipotential surfaces at every point
    • Field lines are parallel to equipotential surfaces at every point
    • Field lines are unrelated to the shape of equipotential surfaces

  5. The electric field is related to the potential gradient. Which equation expresses this relationship for a uniform field between parallel plates?

    • E = V / d
    • E = V^2 / d
    • E = V d
    • E = d / V

  6. A point charge is surrounded by equipotential surfaces. What shape are these surfaces for an isolated point charge?

    • Concentric cylinders centred on the charge
    • Straight lines radiating outwards from the charge
    • Parallel flat planes perpendicular to the charge
    • Concentric spheres centred on the charge

  7. What is the electric potential at a point 0.20 m from a point charge of +4.0 nanocoulomb?

    • 720 V
    • -180 V
    • 45 V
    • 180 V

  8. A charge of 2.0 microcoulomb is moved through a potential difference of 50 V. What work is done?

    • 4.0 x 10^-5 J
    • 2.5 x 10^-8 J
    • 1.0 x 10^-4 J
    • 1.0 x 10^-2 J

  9. The potential difference between two parallel plates is 40 V and their separation is 0.050 m. What is the electric field strength between them?

    • 2000 V m^-1
    • 800 V m^-1
    • 0.00125 V m^-1
    • 8.0 V m^-1

  10. An electron is accelerated from rest through a potential difference of 100 V. What kinetic energy does it gain?

    • 1.6 x 10^-19 J
    • 1.6 x 10^-17 J
    • 1.0 x 10^2 J
    • 6.3 x 10^-19 J

  11. A proton is accelerated from rest through a potential difference of 2.0 kV. What is its kinetic energy?

    • 3.2 x 10^-16 J
    • 2.0 x 10^3 J
    • 1.6 x 10^-19 J
    • 1.3 x 10^16 J

  12. A potential falls by 6.0 V over a distance of 0.030 m in a uniform field. What is the field strength?

    • 600 V m^-1
    • 0.0050 V m^-1
    • 200 V m^-1
    • 18 V m^-1

  13. A charge is moved along an equipotential surface. How much work is done on the charge?

    • Zero, because there is no potential difference along the surface
    • Equal to the charge multiplied by the sum of all potentials on the surface
    • Equal to the charge multiplied by the potential at the starting point
    • Equal to the charge multiplied by the field strength and the distance moved

  14. The potential due to a point charge is measured at distance r and then at distance 2r. How does the second potential compare with the first?

    • It is unchanged
    • It is half as large
    • It is twice as large
    • It is a quarter as large

  15. A +3.0 nC charge and a -3.0 nC charge are 0.60 m apart. What is the potential at the midpoint between them?

    • 180 V
    • -90 V
    • 90 V
    • Zero

  16. A point charge of +2.0 microcoulomb is fixed in place. What is the work done by an external agent in moving a charge of +1.0 microcoulomb from 0.40 m to 0.10 m from it?

    • 0.0045 J
    • 0.27 J
    • 1.35 J
    • 0.135 J

  17. A charge of +2.0 C moves from a point at 10 V to a point at 30 V. What is the work done by the electric field on the charge?

    • +40 J
    • +20 J
    • -20 J
    • -40 J

  18. Why are equipotential surfaces always perpendicular to electric field lines?

    • The field is zero along equipotentials, so the lines must meet them at a right angle
    • Equipotential surfaces carry no charge and therefore must lie at right angles to the field
    • If they were not, the field would have a component along the surface, so moving a charge along it would do work and change its potential
    • Electric field lines are always curved and so must cross equipotentials at right angles by definition

  19. A student says that wherever the electric field is zero, the electric potential must also be zero. Which response is correct?

    • The student is wrong because potential is a vector quantity that cannot be zero anywhere
    • The student is wrong: at the midpoint between two equal like charges the field is zero but the potential is not zero
    • The student is right: zero field always means zero potential everywhere in space
    • The student is right, but only when the charges are equal and opposite

  20. What is the electric potential at a point 0.50 m from a point charge of +4.0 nanocoulomb?

    • -72 V
    • 72 V
    • 144 V
    • 18 V

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