A student places a steel paperclip and an iron nail near a permanent magnet. Both the paperclip and the nail are attracted to the magnet. The student then removes both objects from the magnetic field. Explain why the iron nail quickly loses its magnetism whilst the steel paperclip remains magnetic for much longer.

Edexcel GCSE Physics (1PH0) — 12.1 Magnetism and the motor effect · Explain · 4 marks · View as Markdown

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

Model answer (4 marks)

Both the iron nail and the steel paperclip become induced magnets when they are placed in the magnetic field of the permanent magnet. The magnetic domains in each material align with the external field, giving them a net magnetic moment. When the objects are removed from the field, the domains in the iron nail quickly return to random orientations because iron has a low coercivity, so the nail loses its magnetism rapidly. The steel paperclip, however, has a higher coercivity and the domains remain aligned for a much longer time, so it stays magnetic for a longer period.

Examiner tips

  • Mention ‘induced magnetism’ and ‘magnetic domains’ to show understanding of the mechanism.
  • Explain coercivity – iron has low coercivity, steel high – to justify the difference in time scales.
  • Use the word ‘quickly’ for iron and ‘longer’ for steel to match the mark scheme.
  • Keep the answer concise – 4 marks can be earned with 3–4 short sentences.

Common mistakes

  • Confusing the terms ‘magnetisation’ and ‘induced magnetism’ – both refer to the same process in this context.
  • Saying the steel paperclip loses magnetism quickly – it actually retains it longer.
  • Omitting the concept of coercivity or domain alignment, which is key to the explanation.

Mark scheme (4 marks)

  1. Both the iron nail and the steel paperclip become induced magnets / have magnetism induced when placed in the magnetic field
  2. The magnetic domains in both materials align with the external magnetic field, producing magnetism
  3. When removed from the field, the domains in iron return to random orientations (easily / quickly), so the iron nail loses its magnetism
  4. Steel retains the alignment of its domains / resists the domains returning to random orientations, so the paperclip remains magnetic

Key terms in this question

permanent magnet · magnetic field

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