A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s

Q. A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 Ω and the field winding resistance is 80 Ω. The external resistance to be added in the armature circuit to limit the armature current to 125% of its rated value is

A.            31.9 Ω

B.            31.1 Ω

C.            15.9 Ω

D.            15.1 Ω

Answer: 31.1Ω