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JAMB Physics 1993 Question 34

Question 34

Magnetism

Which of the following correctly explain(s) why soft iron is preferred to steel in electromagnets? I. Soft iron is more readily magnetized than steel II. Soft iron is more readily demagnetized than steel III. Soft iron retains magnetism more than steel.

  1. A.I only
  2. B.II and III only
  3. C.I and II only
  4. D.I, II and III.
Show the answer and explanation

Answer: C (I and II only)

Explanation

Soft iron magnetises strongly when the current flows and loses its magnetism when it stops, so the electromagnet can be switched on and off. Steel keeps its magnetism.