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JAMB Physics 2007 Question 15

Question 15

Alternating Current Circuits

The instrument that measures both a.c. and d.c. is

  1. A.an inverter.
  2. B.a current balance.
  3. C.a moving coil ammeter.
  4. D.a moving iron ammeter.
Show the answer and explanation

Answer: D (a moving iron ammeter.)

Explanation

In a moving-iron meter both irons are magnetised the same way whichever way the current flows, so it deflects for both a.c. and d.c. A moving-coil meter works for d.c. only.