List of top Electrical Engineering Questions on DC Motor asked in OJEE

The armature of a DC motor has resistance of 0.1 ohm and is connected to a 250 V supply. The generated emf when the motor is taking 60 A will be ____.

A load that has a resistance of 10 ohms is to be connected to a supply that has a constant voltage of 120 volts. If it is desired that the current to the load be varied from 3 to 5 amperes, what are the resistance and the current rating of the series rheostat that permit this variation?

Determine the torque developed by a 350 V d.c. motor having an armature resistance of 0.5 $\Omega$ and running at 15 rev/s. The armature current is 60 A.

A dc generator running at 30 rev/s generates an e.m.f. of 200 V. Determine the percentage increase in the flux per pole required to generate 250 V at 20 rev/s.