A steel paper clip and a soft iron nail are both held near the north pole of a bar magnet. Both objects are attracted to the magnet. The bar magnet is then removed. Describe and explain the magnetic behaviour of the steel paper clip and the soft iron nail after the bar magnet is removed.

Cambridge International IGCSE Physics (0625) — 4.1 Simple phenomena of magnetism · Describe and explain · 4 marks · View as Markdown

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

Model answer (4 marks)

The soft iron nail loses its magnetism quickly after the bar magnet is removed, because it is a temporary (induced) magnet and only remains magnetised while in an external magnetic field.

The steel paper clip retains its magnetism after the bar magnet is removed, because steel becomes a permanent magnet and produces its own magnetic field, so it does not need an external field to remain magnetised.

Examiner tips

  • Use the words ‘temporary (induced) magnet’ and ‘permanent magnet’ to match the mark scheme.
  • Show the cause–effect relationship: external field → induced magnetism, removal → loss of magnetism.
  • Mention that steel keeps its own field after removal.

Mark scheme (4 marks)

  1. The soft iron nail loses its magnetism (quickly) once the bar magnet is removed
  2. Because soft iron is a temporary (induced) magnet — it only retains magnetism while in the magnetic field
  3. The steel paper clip retains its magnetism after the bar magnet is removed
  4. Because steel becomes a permanent magnet — it produces its own magnetic field and does not need an external field to remain magnetised

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