O Level / IGCSE Physics chapter 4: Electricity and magnetism MCQs with answers

By Team Megalecture · Updated 4 Nov 2026

176 exam-style questions on Electricity and magnetism, 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.

176 questions · 6 topics · 10 per test

Test this chapter freeAll O Level / IGCSE Physics chapters

What chapter 4 covers

Ten Electricity and magnetism questions with answers

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

1. Resistors of 4.0 Ω and 12 Ω are connected in parallel. The current in the 4.0 Ω resistor is 0.90 A. What is the current in the 12 Ω resistor?

  1. A
    0.30 A
  2. B
    0.90 A
  3. C
    1.2 A
  4. D
    2.7 A
Show answer

Answer: A. Parallel resistors have the same p.d.: V = 0.90 × 4.0 = 3.6 V. Current in 12 Ω = 3.6 ÷ 12 = 0.30 A. The larger resistor takes the smaller current; 2.7 A has the ratio upside down.

2. An oscilloscope trace shows exactly 2 complete cycles across 10 horizontal divisions. The timebase is set to 0.1 ms per division. What is the frequency of the signal?

  1. A
    200 Hz
  2. B
    1000 Hz
  3. C
    2000 Hz
  4. D
    5000 Hz
Show answer

Answer: C. The 10 divisions last 10 × 0.1 ms = 1.0 ms and hold 2 cycles, so the period is 0.5 ms = 0.0005 s. Frequency = 1 ÷ 0.0005 = 2000 Hz. Taking 1.0 ms as one period gives 1000 Hz.

3. Two identical cells, each of e.m.f. 1.5 V, are connected in parallel. This pair is then connected in series with a third identical cell, all facing the same way. What is the total e.m.f.?

  1. A
    1.5 V
  2. B
    2.25 V
  3. C
    3.0 V
  4. D
    4.5 V
Show answer

Answer: C. Identical cells in parallel have the e.m.f. of one cell, 1.5 V. Adding one more cell in series gives 1.5 + 1.5 = 3.0 V. 4.5 V treats all three as in series; 2.25 V wrongly halves the parallel pair.

4. Which change reverses the direction of the magnetic field around a straight current-carrying wire?

  1. A
    increasing the current
  2. B
    reversing the current
  3. C
    using a thicker wire
  4. D
    moving the wire faster
Show answer

Answer: B. The field direction depends on the current direction (right-hand grip rule). Reversing the current reverses the field.

5. A cell, a switch and a lamp are in series. A student wrongly connects an ammeter in parallel with the lamp and closes the switch. What happens?

  1. A
    the lamp goes out or is very dim and the ammeter shows a large current
  2. B
    the lamp lights normally and the ammeter reads zero
  3. C
    the lamp becomes brighter and the ammeter reads zero
  4. D
    the lamp lights normally and the ammeter shows the lamp current
Show answer

Answer: A. An ammeter has a very low resistance, so in parallel it short-circuits the lamp: almost all the current goes through the ammeter, which may be damaged. Ammeters must be in series.

6. A student has several 5.0 Ω resistors. How many must be connected in series to give a combined resistance of 35 Ω?

  1. A
    4
  2. B
    5
  3. C
    6
  4. D
    7
Show answer

Answer: D. In series the resistances add: 35 ÷ 5.0 = 7 resistors.

7. Which list contains only electrical insulators?

  1. A
    rubber, dry wood and glass
  2. B
    copper, graphite and steel
  3. C
    aluminium, plastic and glass
  4. D
    steel, rubber and silver
Show answer

Answer: A. Rubber, dry wood and glass are insulators. Metals (copper, steel, aluminium, silver) and graphite are conductors.

8. As the current through a filament lamp increases, its resistance

  1. A
    decreases, because the filament gets hotter
  2. B
    increases, because the filament gets hotter
  3. C
    stays constant, because it obeys Ohm's law
  4. D
    becomes zero
Show answer

Answer: B. The filament heats up; the metal ions vibrate more and impede the electrons, so resistance rises. This is why the I–V graph of a lamp curves.

9. For which task is an electromagnet more suitable than a permanent magnet?

  1. A
    holding a fridge door closed
  2. B
    making a compass needle
  3. C
    a crane that lifts scrap steel and then releases it
  4. D
    holding notes on a metal board
Show answer

Answer: C. An electromagnet can be switched off, so the crane can drop the steel where it is needed. Permanent magnets suit jobs where the magnetism must stay on all the time.

10. An oscilloscope trace reaches 4.0 divisions above the centre line. The Y-gain is set to 5 mV per division. What is the peak p.d. in volts?

  1. A
    0.0020 V
  2. B
    0.020 V
  3. C
    1.25 V
  4. D
    20 V
Show answer

Answer: B. Peak p.d. = 4.0 × 5 mV = 20 mV = 20 × 10−3 V = 0.020 V. Writing 20 mV as 20 V misses the milli-; 1.25 comes from dividing 5 by 4.

Start the chapter testAbout the O Level / IGCSE Physics test

Read the notes for this chapter

Ways to practise this chapter

Electricity and magnetism: questions students ask

How many Electricity and magnetism MCQs are there?

176, each with the answer and a short explanation, across 6 topics: Simple magnetism and magnetic fields, Electrical quantities, Electric circuits, Practical electricity, Electromagnetic effects, Uses of an oscilloscope. Every chapter test draws ten of them, so you can take it many times.

Is the O Level / IGCSE Physics chapter 4 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 3: WavesChapter 5: Nuclear physics →All chaptersStuck? Ask a question