Question

If you’ve ever unplugged a fan, you might have noticed a big spark as the plug was removed from the wall socket. Here’s why: A fan motor has 4.35H of inductance when the current suddenly changes at the rate of 320A/s. What’s the voltage produced? Once again, ignore the sign.

A) 73.6V B) 0.0136V C) 1392V D) 18.3V

Answer 1

where E = voltage

L = Inductance of the coil = 4.35 H

I = current

dI/dt = rate of change of current = 320 A/sec

hence E = 4.35*320 = 1392 V.

Ans is (c).