A Level Physics (A2) chapter 7: Electric fields MCQs with answers

By Team Megalecture · Updated 4 Nov 2026

120 exam-style questions on Electric fields, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.

120 questions · 5 topics · 10 per test

Test this chapter freeAll A Level Physics (A2) chapters

What chapter 7 covers

Ten Electric fields questions with answers

Try each one, then open the answer. These ten stay the same; the test draws new ones every time.

1. An electron enters the uniform field between two parallel plates with speed v, moving parallel to the plates, and leaves them having been deflected sideways by a distance y. The electron is now sent in with speed 2v. What is its sideways deflection as it leaves the plates?

  1. A
    y/2
  2. B
    y/4
  3. C
    2y
  4. D
    4y
Show answer

Answer: B. The sideways acceleration is unchanged but the time between the plates is halved. The deflection is ½at2, so it falls to (½)2 = ¼ of y. y/2 forgets that t is squared.

2. Two identical small metal spheres carry charges of +6.0 μC and −2.0 μC. They are touched together and then placed with their centres 0.30 m apart. What is the force between them now?

  1. A
    0.40 N, repulsive
  2. B
    0.40 N, attractive
  3. C
    1.2 N, attractive
  4. D
    1.6 N, repulsive
Show answer

Answer: A. On touching, the total charge +4.0 μC is shared equally: +2.0 μC each. F = 8.99 × 109 × (2.0 × 10−6)2/0.302 = 0.40 N, and like charges repel. 1.2 N is the attraction before touching.

3. A dust particle of mass 6.4 × 10−15 kg carries a charge of −3.2 × 10−18 C. It is held stationary by a vertical uniform electric field. What is the electric field?

  1. A
    2.0 × 104 N C−1, upwards
  2. B
    2.0 × 103 N C−1, downwards
  3. C
    5.1 × 10−5 N C−1, upwards
  4. D
    2.0 × 104 N C−1, downwards
Show answer

Answer: D. The electric force must be upwards to balance the weight: E = mg/q = 6.4 × 10−15 × 9.81/(3.2 × 10−18) = 2.0 × 104 N C−1. The charge is negative, so the force is opposite to the field and the field must point downwards.

4. Estimate the size of the force between two point charges of 1.0 C each, 1.0 m apart in a vacuum.

  1. A
    8.9 × 10−12 N
  2. B
    1.1 × 10−10 N
  3. C
    1.0 N
  4. D
    9.0 × 109 N
Show answer

Answer: D. F = 8.99 × 109 × 1.0 × 1.0/1.02 = 9.0 × 109 N, showing that one coulomb is an enormous charge. 8.9 × 10−12 is ε0 and 1.1 × 10−10 is 4πε0.

5. Two horizontal parallel plates are at potentials of 0 V and 400 V. An electron enters midway between the plates, moving parallel to them, and is deflected until it strikes the 400 V plate. How much kinetic energy does it gain from the field?

  1. A
    0 J
  2. B
    1.6 × 10−17 J
  3. C
    3.2 × 10−17 J
  4. D
    6.4 × 10−17 J
Show answer

Answer: C. The potential midway is 200 V, so the electron moves through 400 − 200 = 200 V: ΔEK = eΔV = 1.60 × 10−19 × 200 = 3.2 × 10−17 J. 6.4 × 10−17 J uses the full 400 V.

6. How is the electric field strength E at a point related to the potential V?

  1. A
    E is equal to the potential gradient, E = dV/dx
  2. B
    E is equal to the potential multiplied by the distance, E = Vx
  3. C
    E is equal to the negative of the potential gradient, E = −dV/dx
  4. D
    E is equal to the area under a graph of V against x
Show answer

Answer: C. E = −dV/dx: the field points in the direction in which the potential falls, and its size is the magnitude of the potential gradient. For parallel plates this gives E = V/d.

7. Plates X are 2.0 mm apart with 200 V across them. Plates Y are 4.0 mm apart with 600 V across them. What is (field strength between Y) ÷ (field strength between X)?

  1. A
    0.67
  2. B
    1.5
  3. C
    3.0
  4. D
    6.0
Show answer

Answer: B. EX = 200/0.0020 = 1.0 × 105 V m−1; EY = 600/0.0040 = 1.5 × 105 V m−1. The ratio is 1.5. 6.0 multiplies by the separation instead of dividing.

8. In a hydrogen atom the electron and the proton are about 5.3 × 10−11 m apart. What is the size of the electric force between them?

  1. A
    8.2 × 10−8 N
  2. B
    4.3 × 10−18 N
  3. C
    5.1 × 1011 N
  4. D
    3.6 × 10−47 N
Show answer

Answer: A. F = e2/(4πε0r2) = 8.99 × 109 × (1.60 × 10−19)2/(5.3 × 10−11)2 = 8.2 × 10−8 N. 3.6 × 10−47 N is the far weaker gravitational force between them.

9. Point charges of +4Q and +Q are fixed 0.30 m apart. A third charge is placed on the line between them, at the point where the resultant electric force on it is zero. How far is this point from the +4Q charge?

  1. A
    0.10 m
  2. B
    0.24 m
  3. C
    0.15 m
  4. D
    0.20 m
Show answer

Answer: D. 4Q/x2 = Q/(0.30 − x)2, so x/(0.30 − x) = 2 and x = 0.20 m: the point is nearer the smaller charge. 0.24 m comes from using 1/r instead of 1/r2.

10. What is (electric force between two protons) ÷ (gravitational force between the same two protons)?

  1. A
    1.2 × 1036
  2. B
    1.3 × 1028
  3. C
    1.1 × 1018
  4. D
    4.2 × 1042
Show answer

Answer: A. Both forces follow an inverse-square law, so the separation cancels: ratio = e2/(4πε0Gmp2) = 8.99 × 109 × (1.60 × 10−19)2/(6.67 × 10−11 × (1.67 × 10−27)2) = 1.2 × 1036. 4.2 × 1042 comes from using the electron mass.

Start the chapter testAbout the A Level Physics (A2) test

Read the notes for this chapter

Ways to practise this chapter

Electric fields: questions students ask

How many Electric fields MCQs are there?

120, each with the answer and a short explanation, across 5 topics: Electric fields and field lines, Uniform electric fields, Electric force between point charges, Electric field of a point charge, Electric potential. Every chapter test draws ten of them, so you can take it many times.

Is the A Level Physics (A2) chapter 7 test free?

Yes. The test, the answers and the explanations are free and need no sign-up. Sign in only if you want your scores kept across devices.

How is the chapter test marked?

The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.

Keep going

← Chapter 6: OscillationsChapter 8: Capacitance →All chaptersStuck? Ask a question