CBSE Class 10 Answered

JOULES HEATING:

When an  electric current flows through a high resistance wire like nichrome wire,  the resistance wire becomes very hot and produces heat. This is actually the heating effect of current . The heat produced when a current I flows through a wire of resistance R ohms for time t seconds is given by the Joules law of heating.

According to Joules law of heating the heat produced in a wire is directly proportional to:

1. square of current (I²)

2. resistance of wire (R)

3. time(t) for which the current flows

i.e. Heat produced, H = I²RT  

SPLIT RINGS

Split rings are used in electric motors.An electric motor is a device which converts the electrical energy into mechanical energy.

A Split ring (or commutator) is a device which reverses the direction of current through a circuit. In an electric motor the split ring commutator reverses the direction of current flowing through the coil after every half rotation of the coil.