A 250 V DC shunt motor has an armature resistance of 0.55 2 and runs with a full load armature current of 30A. The field current remaining constant, if an additional resistance of 0.75 22 is added in series with the armature, the motor attains a speed of 633 rpm. If now the armature resistance is restored back to 0.552, find the speed with (i) full load and (ii) twice full load torque. (12)