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. What will be the magnitude of the following current at t=0+?

(a) 400A

(b) 200A

(c) 0

(d) any of the mentioned

I have been asked this question at a job interview.

The above asked question is from Torque in DC Machines in section Electromechanical Energy Conversions of Electrical Machines

Answer 1

Right answer is (a) 400A

Easiest explanation: I = (V-E)/r

              = (120-0)/0.3

       = 400 A.