Question -9 The resistance of the armature circuit of a 250 V de shunt motor is
0.3\Omega
and its full-load speed is 1000 rpm . Calculate the resistance required in series with the armature to reduce the speed with the full-load torque to 800 rpm , the full-load armature current being 50 A . If the load torque is then halved, at what speed will the motor run?