A 240 V shunt motor has an armature current of 15 A when running at 800 rpm against full-load torque. The armature resistance is 0.6 ohm. What resistance must be inserted in series with the armature to reduce the speed to 400 rpm at the same torque? What will be the speed if the load torque is halved with this resistance in the circuit? Assume the flux to remain constant throughout.

A 240 V shunt motor has an armature current of 15 A when running at 800 rpm against full-load torque. The armature resistance is 0.6 ohm. What resistance must be inserted in series with the armature to reduce the speed to 400 rpm at the same torque? What will be the speed if the load torque is halved with this resistance in the circuit? Assume the flux to remain constant throughout.