Home Engineering What is a Transformer – Working principle of transformer

What is a Transformer – Working principle of transformer

Working principle of transformer

Transformer – What is a Transformer ?

Transformer is a electrical device which is static and transfers electrical energy between two or more circuits through electromagnetic induction. In transformer a varying current in one coil produces a varying magnetic field that in turn induces a varying electromotive force which is known as “EMF” or “voltage” in a 2nd coil. Here in transformer, power can be transferred or move between the 2 coils through the magnetic field and that is without a metallic connection between the two circuits. In 1831, Faraday’s law of induction discovered and described this effect. People generally use transformers to increase or decrease the alternating voltages in electric power applications.

Working principle of transformer

Working principle of transformer depends upon the Faraday’s electromagnetic induction law. The law described that the mutual induction phenomenon that is working between two or more winding is the fact that is responsible for power transformation.


We know from Faraday’s laws, “The rate of change of linkage flux with respect to the time is directly proportional to the EMF that induced in the conductor or coil”.

Faraday’s law of induction

So we can write the equation:

E= N d /dt



N = the number of turns

E = Induced EMF

dt = Change in time

d= Change in flux


This was the working principle of transformer.


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