State the principle of working of a transformer. Can a transformer be used to step up or step down a d.c. voltage? Justify your answer.

Explanation

The working principle of the transformer is the mutual induction. The nmagnetic fiux linked with the primary winding of the transformer must change, to produce an induced emf in the secondary coil. Transformer cannot work on DC voltages. If a DC'supply is giving to the primary coil of a transformer, it produces a steady magnetic flux, So, no emf will be induced in the secondary coil.