JEE Main · 2004 · 24 Apr 2004 · Offline · Magnetic Properties of Matter

The materials suitable for making electromagnets should have

(A)high retentivity and high coercivity
(B)low retentivity and low coercivity✓ Correct
(C)high retentivity and low coercivity
(D)low retentivity and high coercivity

Answer: (B)

Solution

An electromagnet must take up and lose its magnetism readily as the current is switched. Low retentivity means it keeps almost no magnetism once the current stops, and low coercivity means little effort is needed to reverse or remove the magnetisation. So the core should have low retentivity and low coercivity.

JEE Main · 2004 · 24 Apr 2004 · Offline · Single correct option

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