Question

prove that the starting torque of 1 phase induction motor is zero?

Answer 1

So the net torque developed is zero and hence single phase induction motor is not self starting. BUT in single phase induction motor there is single phase supply to the stator of motor. A SINGLE PHASE SUPPLY CAN NOT PRODUCE A ROTATING MAGNETIC FIELD BUT IT PRODUCE A PULSATING MAGNETIC FIELD WHICH DOES NOT ROTATE.