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Two identical-looking iron bars A and B; one is a magnet, the other unmagnetised iron. The CORRECT test using only the two bars is to
ADrop them on a table and listen for the sound
BBring an end of A to an END of B — both attract regardless
CBring an end of A to the MIDDLE of B. If no force is felt, B is the magnet; otherwise A is.
DTry to align them with the earth's field
Answer & Solution
Correct answer: C. Bring an end of A to the MIDDLE of B. If no force is felt, B is the magnet; otherwise A is.
A magnet's field is strongest at its poles, weakest at its centre. If A felt no force near B's middle, A's end is being attracted by no nearby pole — meaning B is the magnet (its centre has no net pole). If force is felt regardless, A must be the magnet.
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