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JAMB Physics 1989 Question 45

Question 45

Magnetism

The figure above shows a conductor PQ carrying a current I in the direction shown. At a particular position near the conductor is a compass needle K. Neglecting the earth's magnetic field, the compass needle will

Diagram for this question
  1. A.settle in any direction
  2. B.settle in a fixed direction only if conductor PQ is a magnetic material
  3. C.settle in a fixed direction whether conductor PQ is a magnetic material or not
  4. D.be stationary
Show the answer and explanation

Answer: C (settle in a fixed direction whether conductor PQ is a magnetic material or not)

Explanation

Any current produces a magnetic field around it, whatever the wire is made of, so the needle settles along that field.