Working Principal
The physical basis of a transformer is mutual inductance between two circuits linked by a common magnetic flux. In it simplest form, it consists of two inductive coils which are electrically separated but magnetically linked through a path of low reluctance as shown in Fig. The two coils possess high mutual inductance. If one coil is connected to a source of alternative voltage, an alternative flux is set up in the laminated core, most of which is linked with other coil in which it produces mutually induced e.m.f. (according to Faraday's Laws of Electromagnetic Induction e = MdI/dt). If the second coil circuit is closed, a current flows in it and so electric energy is transferred (entirely magnetically) from first coil to the second coil. The first coil, in which electric energy is fed from the a.c. supply mains, is called primary winding and the other from which energy is drawn out, is called secondary winding.
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