What is transformer ? Write its principle and write its construction.

Explanation

Transformer is a device which can incrase or decrease the AC voltage.
The transformer which increase the voltage are called step-up transformers, while transformers which decreases the voltage are called step-down transformers.
Principle `:` Transformer works on the principle of the electromagnetic induction.
Construction `:` A transformer consists of two sets of coils insulated from each other.
As shown in figure ( a+b) , the coils are wound on a sof -iron core either one on top of the other or on separate limbs of the core. One of the coils called the primary coil has `N_(p)` turns . The other coil is called the secondary coil has `N_(s)` turns. The primary coils is the input coil the secondary coil is output coil of the transformer.
The coils are wounded by two ways `:`
(1) Core type`:` Coils are wound on a soft iron core on separate limbs of core as in figure .
(2) Shell type `:` Coils are wound on a soft iron core, either one on top of the other as in figure.