The correct answer is: B. helps the rotor teeth to remain under the stator teeth.
The rotor slots are usually not quite parallel to the shaft in an induction motor because it helps the rotor teeth to remain under the stator teeth. This is important because it ensures that the magnetic field produced by the stator is able to induce a current in the rotor, which in turn creates a magnetic field that opposes the stator field. This interaction of the stator and rotor fields is what causes the rotor to turn.
If the rotor slots were parallel to the shaft, the rotor teeth would not be able to remain under the stator teeth as the rotor turned. This would cause the magnetic field produced by the stator to be less effective at inducing a current in the rotor, which would reduce the torque produced by the motor.
The other options are incorrect because:
- Option A is incorrect because it does not improve the efficiency of the motor.
- Option C is incorrect because it does not help in reducing the tendency of the rotor teeth to remain under the stator teeth.
- Option D is incorrect because it does not improve the power factor of the motor.