if i change voltage will the rpm of motor will be affected
if it is dc motor speed is proportional to voltage. for induction motor without load it will not depend on voltage much but only frequency
I agree with the previous answer. Also, In an induction motor when you lower the voltage the current will increase to compensate and attempt to keep the motor running. With AC motors, in order to regulate the speed, one has to use a Variable Frequency Drive or VFD. The VFD can change the frequency, and hense, speed, in order to keep up with a certain demand. Often they are used on water pump stations and conveyor belts where the demand for product may change.
