ELECTROMAGNETISM
2 marks · NormalExplain why a soft iron core is used in an electromagnet rather than a steel core.
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A soft iron core is used because it is magnetically soft and loses its magnetism quickly when the current stops, making the electromagnet easy to turn on and off.
Also accept: Steel is magnetically hard so would remain magnetised after switching off
Common mistakes: Saying steel is stronger than iron
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Marking points
B1 · 1 mark · States that soft iron loses magnetism quickly/has temporary magnetism.
B2 · 1 mark · Relates this to switching electromagnet on/off easily.
Worked solution
Because soft iron is magnetically soft, it becomes a magnet quickly when the current flows, but loses its magnetism just as quickly when the current stops. This makes it ideal for electromagnets that need to be switched on and off.