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JAMB Physics 1984 Question 33

Question 33

Electromagnetic Induction

The electromotive force obtained from a simple dynamo may be increased by

  1. A.increasing the cross-sectional area of the coil
  2. B.winding the coil on a soft-iron armature so as to decrease the magnetic flux through the coil
  3. C.increasing the speed of rotation
  4. D.making the field magnet longer
  5. E.using low-resistance copper coils.
Show the answer and explanation

Answer: C (increasing the speed of rotation)

Explanation

The induced e.m.f. depends on how fast the flux linkage changes, so spinning the coil faster gives a bigger e.m.f.