What is a Transformer?

A transformer is a passive electrical device that transfers electrical energy from one electrical circuit to another, or multiple circuits. It is made up of two coils all wound on a soft iron core. A transformer makes use of the principle of mutual induction to change voltage. The coil connected to the a.c. input is called the primary coil while the coil that is connected to the ac. Output is called the secondary coil. The ac. Input in the primary coil induces a flux in the secondary coil through the soft iron core. Since the supply from the primary coil is alternating, an alternation flux is also generated in the secondary coil because field lines are continuously cut as they fluctuate. A transformer cannot operate when the supply is dc because the dc supply in the primary coil will not produce any change in the magnetic field in the secondary coil.