A DC Motor is driving a constant load torque having armature resistance of 0.15 Ω and armature current of 0.25 A having connected to a voltage of 230 V

Q. A DC Motor is driving a constant load torque having armature resistance of 0.15 Ω and armature current of 0.25 A having connected to a voltage of 230 V. Now a resistance of 1 ohm is added into the armature circuit. The ratio of their speed will be

A.            0.25

B.            1.24

C.            0.62

D.            0.72

Answer: 0.72