An electric current produced by means of electrical machine is known as generator which converts mechanical energy into electrical energy. When conductor cuts the magnetic flux, emf induced in it. (Faraday’s Law of electromagnetic induction). Thus, for generation of emf relative motion between magnetic field and conductor is required.
Here single turn rectangular elementary coil (AB) is made up of conducting material. The coil is so placed that it can be rotated about its own axis with constant speed in a uniform magnetic field provided by permanent magnet. Assume that the coil (AB) rotates in anticlockwise direction and cuts magnetic flux. According Faraday’s law of electromagnetic induction, emf is induced and magnitude of generated emf depends upon position of armature. The nature of emf is alternating as shown by the waveform.