A. Working principle of Transformer is based on Faraday’s Laws of Electromagnetic Induction. If an alternating current is applied to an electric coil, there will be an alternating flux surrounding that coil. Now if we bring another coil near the first one, there will be an alternating flux linkage with that second coil. As the flux is alternating, there will be obviously a rate of change of flux linkage with respect to time in the second coil. Therefore emf will be induced in it as per Faraday’s laws electromagnetic induction.