A student wraps a length of insulated wire around an iron bar to make an electromagnet. Explain how the student could increase the strength of the electromagnet, giving two different methods.

Eduqas GCSE Physics — 2.5 Magnetism and electromagnetism · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Increase the number of turns of wire around the iron bar – more turns mean more magnetic field lines, so the field is stronger.
Increase the current through the wire – a larger current produces a stronger magnetic field, magnetising the iron bar more strongly.

Examiner tips

  • Use the exact phrases "increase the number of turns" and "increase the current". Show the causal link: more turns → stronger field, higher current → stronger field. Keep the answer to two short sentences to match the 4‑mark structure.

Common mistakes

  • Writing only one method instead of two. Using vague wording such as "make it stronger" without specifying turns or current. Mixing up the roles of wire and iron bar in the explanation.

Mark scheme (4 marks)

  1. Increase the number of turns/coils of wire (around the iron bar)
  2. More turns produces a stronger magnetic field because more wire contributes to the field / the fields from each turn add together
  3. Increase the current through the wire
  4. A larger current produces a stronger magnetic field around the wire / more current magnetises the iron bar more strongly

Key terms in this question

electromagnet · iron bar

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