Question

on which principal of electric motor based

Answer 1

 Electrical MotorThe electric motor is a device which converts electrical energy to mechanical energy. There are mainly three types of electric motor. All of these motors work in more or less same principle. Working of electric motor mainly depends upon the interaction of magnetic field with current.

Answer 2

Electrical MotorThe electric motor is a device which converts electrical energy to mechanical energy. 
There are mainly three types of electric motor.
 1) DC Motor
 2) Induction Motor
 3) Synchronous Motor.
All of these motors work in more or less same principle. Working of electric motor mainly depends upon the interaction of magnetic field with current.    Now we will discuss the basic operating principle of electric motor one by one for better understanding the subject.

Principle: 
    It is based on the principle that when a current-carrying conductor is placed in a magnetic field, it experiences a mechanical force whose direction is given by Fleming's Left-hand rule and whose magnitude is given by
                     Force,F = B I l newton      
                       Where B is the magnetic field in weber/m2. 
                                 I is the current in amperes and  
                                 l is the length of the coil in meter.              
The force, current and the magnetic field are all in different directions.