Question

The simple rotating loop between pole faces connected to a battery and resistor through a switch, the specifications of this machine are radius = 0.5m, length 1m, resistance = 0.3 ohms and magnitude strength = 0.25T is supplied with 120V. Suddenly the switch is closed at t=0, what is observed in the circuit?

(a) Current will flow but zero induced EMF

(b) Current will not flow and zero induced EMF

(c) Current will not flow but EMF is induced

(d) Current will flow and EMF will also be induced

The question was posed to me in an international level competition.

This question is from Torque in DC Machines topic in section Electromechanical Energy Conversions of Electrical Machines

Answer 1

Correct option is (a) Current will flow but zero induced EMF

To elaborate: Initially the induced emf in the armature is zero. But the current will flow as there is terminal source voltage.