Induced magnetism
4 marks · NormalA student holds a steel nail and an iron nail next to a bar magnet for several minutes. The magnet is then removed.
Describe what happens to the magnetism in each nail after the magnet is taken away.
Explain the difference in the behaviour of the iron and steel nails.
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(a) The iron nail loses its magnetism quickly but the steel nail remains magnetised.
(b) Iron is magnetically soft so its induced magnetism is temporary; steel is magnetically hard and retains magnetism.
Common mistakes: Saying both nails lose magnetism instantly
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · States the iron nail loses magnetism after the magnet is removed.
B2 (a) · 1 mark · States the steel nail remains magnetised.
M1 (b) · 1 mark · States iron is magnetically soft and magnetism is temporary.
A1 (b) · 1 mark · States steel is magnetically hard and retains some magnetism.
Worked solution
a) The iron nail loses its magnetism once the bar magnet is removed. The steel nail stays magnetised (it remains a magnet).
b) This is because iron is magnetically soft, so its induced magnetism is temporary and is lost as soon as the field is removed. Steel is magnetically hard, so it keeps some of its magnetism after the field is removed.