For an induction motor operating with a slip of 0.2, the ratio of rotor input power to rotor copper losses is:

The power input to a 4-pole, 3-phase, 50 Hz induction motor is 50 kW, and the slip is 5%. The stator losses are 1.2 kW. Determine the rotor copper losses.

The rotor of an 8-pole, 50 Hz, 3-phase induction motor has a rotor resistance of 0.4 Ω/phase and runs at 720 rpm. For a constant load torque, calculate the additional rotor resistance per phase that must be inserted to reduce the speed by 25%.