In a d.c. motor, why must the current to the coil be reversed twice during each rotation ?

State Fleming's left-hand rule. Explain it with the help of labelled diagrams.

What is the principle of an electric motor? Name some of the devices in which electric motors are used.

What device reverses the current?

State what would happen to the direction of rotation of a motor if :

(i) the current were reversed

(ii) the magnetic field were reversed

(iii) both current and magnetic field were reversed simultaneously.