Solved: PHYSICS Question for NEET

NEET PHYSICSEasy

Electromagnets are made of soft iron because soft iron has:

low retentivity and high coercive force

high retentivity and high coercive force

low retentivity and low coercive force

high retentivity and low coercive force

Function of Electromagnets: Electromagnets are temporary magnets that must behave as magnets only when a current flows through the solenoid and lose their magnetism immediately when the current is switched off.
Properties Required:

Low Retentivity: The material should retain minimum magnetism when the magnetising field is removed. If retentivity is high, the core would act like a permanent magnet even after the current stops.
Low Coercivity: The material should be easily demagnetised. It should require a very small (or zero) reverse field to wipe out the residual magnetism. This also implies low hysteresis loss, which is crucial for efficiency.
High Permeability: It should be easily magnetised to a strong value by the current.

Soft Iron vs. Steel: Soft iron is a ferromagnetic material with low retentivity, low coercivity, and high permeability. In contrast, steel (used for permanent magnets) has high retentivity and high coercivity .
Conclusion: Soft iron is selected for electromagnets because of its low retentivity and low coercive force.

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