Why do we use a transformer in AC circuits?

Explanation

Transformers work on the principle of mutual induction. When current in the primary coil changes, then it induces current in the secondary coil. If we drive steady current (DC) in primary coil, then once current is set up in the circuit, there will not be any output in the secondary coil. Due to steady current , magnetic flus linked with secondary coil remains constant and so no emf is induced in it.