Soft iron rather than steel is used for the core of an electromagnet because soft iron
- A. is cheaper
- B. loses its magnetism quickly when the current is switched off
- C. retains its magnetism permanently
- D. conducts electricity better
Explanation
An electromagnet must be able to be switched off, which requires a core of low retentivity, and soft iron is easily magnetised and just as easily demagnetised. Steel retains magnetism and is therefore used for permanent magnets instead. This difference in hysteresis behaviour is the whole basis of choosing between them.
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