1. Key ideas 21.2 Application of electromagnetic induction  Electromagnetic induction is used in microphones tape recording and playback generation of electricity  A generator converts mechanical energy into electrical energy.

2. induced current number of revolution 1  When the coil of an a.c. generator rotates, the alternating current induced in the coil flows to the external circuit via a pair of slip rings.  The current reaches maximum when the coil is at the horizontal position and is zero when the coil is at the vertical position.

3.  A d.c. generator is the same as a d.c. motor. A commutator is used to reverse the connections of the coil with the external circuit. Therefore, the induced current always flows in the same direction. induced current number of revolution 1

4.  The current induced in generators can be increased by Using a stronger magnet winding more turns of wire around the coil winding the coil on a soft iron core increasing the area of the coil rotating the coil at a higher speed  The a.c. generator in a power station consists of a rotor and a stator. When the rotor is rotated by a turbine, an alternating current is induced in the stator coils.