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JAMB Physics 1979 Question 33

Question 33

Magnetism

Fig. 8 shows a current I flowing in a copper wire situated in the magnetic field existing between the pole-pieces of a horse-shoe magnet. Which of the following statements is correct?

Diagram for this question
  1. A.The wire will experience a force in the direction into the paper.
  2. B.The wire will experience a force in the direction out of the paper
  3. C.The wire will vibrate in the direction into and out of the paper
  4. D.The wire will move in the direction of the field, i.e. towards the S-pole
  5. E.The wire will not move because it is made of copper which is non-magnetic.
Show the answer and explanation

Answer: A (The wire will experience a force in the direction into the paper.)

Explanation

The field runs from N to S (left to right) and the current runs up the page. By Fleming's left-hand rule the force is perpendicular to both, into the paper.