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EEJ MAIN Physics QUESTION #7008
Question 1

Two magnetic materials A and B have different hysteresis loops. Material A has a wide, large-area loop and material B has a narrow, small-area loop. For use in electric generators, transformer cores, and electromagnet cores, the correct assignment is:

  • A for electromagnets and B for electric generators
  • A for transformers and B for electric generators
  • B for electromagnets and transformers✔️
  • A for electric generators and transformers
Correct Answer Explanation

Key properties:

  • Wide hysteresis loop (A): High retentivity and high coercivity — hard magnetic material. Good for permanent magnets (used in electric generators).
  • Narrow hysteresis loop (B): Low retentivity, low coercivity, low energy loss per cycle — soft magnetic material. Ideal for transformers and electromagnets (needs to magnetise/demagnetise repeatedly with low loss).

Electric generators use permanent magnets (wide loop, material A). Transformers and electromagnets use soft material (B). So Option C is correct.