question_answer 20)

  A cylindrical bar magnet is rotated about its axis. Fig. 4(EP).1. A wire is connected from the axis and is made to touch the cylindrical surface through a contact. Then (a) a direct current flows in the ammeter A (b) no current flows through the ammeter A (c) an alternating sinusoidal current flows through the ammeter A with a time period (d) a time varying non-sinosoidal current flows through the ammeter A

Answer:

  (b)As there is no change in magnetic flux associated with the circuit, no current is induced in the circuit. The ammeter A shows no deflection. Choice (b) is correct