(a) State Fleming's left hand rule.
(b) Write the principle of working of an electric motor.
(c ) Explain the function of the following parts of an electric motor.
(i) Armature , (ii) Brushes , (iii) Split ring

Explanation

(a) Fleming's left hand rule, According to Fleming's left hand rule, hold the forefinger, the centre finger and the thumb of your left hand at right angles to one another. Adjust your hand in such a way that the forefinger points in the direction of magnetic field and the centre finger points in the direction of force acting on the conductor.
(b) Principle of an electric motor. The working principle of an electric motor is based on the magentic effect of current. An electric motor works on the principle that when a rectangular coil is placed in a magnetic field and current is passed through it, a force acts on the coil which rotates it continuously. It is based on Fleming's left hand rule.
(c ) (i) Armature . It is the rotating part of a motor. Armature is a coil which carries current and rotates in the magentic field.
(ii) Brushes. The function of carbon brushes is to make contact with the rotating split-rings of the commutator so as to supply current to the coil.
(iii) Spilt ring. The function of split rings is to reverse the direction of current flowing through the coil every time the coil passes the vertical position during a revolution.