Transformer

Transformer: Transformer is an electrical device which transfers electrical energy through inductively coupled conductors. These inductive conductors are called coils. From Faraday's Law, we know if we give a varying current in the first or primary winding then in the core a varying magnetic flux will be induced. Thus it will induce a varying magnetic field in secondary winding. This varying magnetic field induces a varying electromotive force (EMF), or "voltage". This effect is known as inductive coupling.

Current will flow in the secondary winding, if a load is connected to it, and from the primary circuit through the transformer to the load electrical energy will be transferred . The induced voltage of an ideal transformer in the secondary winding (V_s) is in proportion to the primary voltage (V_p). It is given by the ratio which is usually called as transformer's turns ratio. The  turns ratio is ratio of the number of turns in the secondary (N_s) to the number of turns in the primary (N_p) as follows:

By appropriate selection of the turns ratio, a transformer enables an alternating current (AC) voltage to be "stepped up" or "stepped down" by making N_s greater than N_p, or by making N_s less than N_p respectively. In most of the transformers, the windings are coils wound around a ferromagnetic core.

Transformers can be of different sizes. One can be size of a thumbnail hidden inside a stage microphone, while other can be huge units weighing hundreds of tons used to interconnect portions of power grids. But all of them operates according to the same principles. 


Now-a-days new technologies have somehow eliminated the need for transformer in some electronic circuit. But still transformers are found in almost all electronic devices which are designed for household use. Transformer are must for high voltage electric power transmission. It makes long distance transmission economical and practical.