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NEET PHYSICSMAGNETISM AND MATTEREasy

Question

Electromagnets are made of soft iron because soft iron has:

A

low retentivity and high coercive force

B

high retentivity and high coercive force

C

low retentivity and low coercive force

D

high retentivity and low coercive force

Step-by-Step Solution

  1. 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.
  2. 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.
  1. 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 .
  2. Conclusion: Soft iron is selected for electromagnets because of its low retentivity and low coercive force.

Exam Context & Concepts Covered

This question aligns with the NEET PHYSICS syllabus, specifically targeting concepts from MAGNETISM AND MATTER. Mastering this topic is crucial for scoring well in the upcoming medical entrance examinations. Solving conceptually related problems will help you understand the nuances of these concepts and improve your problem-solving speed.

PHYSICSMAGNETISM AND MATTERelectromagnetsbecause

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