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JAMB Physics 2014 Question 40

Question 40

Magnetism

What is the best method of demagnetizing a steel bar magnet?

  1. A.Heating it.
  2. B.Rough handling it.
  3. C.Solenoid method.
  4. D.Hammering.
Show the answer and explanation

Answer: C (Solenoid method.)

Explanation

Placing the magnet in a solenoid carrying a.c. and slowly pulling it out (east–west) jumbles its domains without damaging it. This is the best method.