Question

Write a note on transformer with special reference to principle, construction and working.

Answer 1

It is a device used to increase or decrease the AC. It works on the principle of mutual induction.

A transformer consists of two sets of coils, insulated from each other. They are wound on a softiron core. One of the coil is called primary (input) with N_P turns and the other is called secondary (output) with N_S turns. When an alternating voltage v_p is applied to the primary, the induced magnetic flux is linked to the secondary through the core. So an voltage vs is induced in secondary If N_s > N_p then transformer is called Step up transformer; where v_s > v_p, and if N_p > N_s, then the transformer is called Step down transformer; where v_s < v_p. If the transformer is ideal,

p_in = p_out, i.e., i_pv_p = i_sv_s. 

ELECTRICAL SYMBOLS OF TRANSFORMERS :