Question

Why isn't direct current used in transformers​

Answer 1

Direct current has no time varying field because current is constant as well as there is no relatively motion between coil and core of the transformer. So there is no induced emf in secondary coil of the transformer. Thus, direct current supply is not used for transformers.

Answer 2

No, it will not and this has a historical importance. The reason is that transformers work via induction of electrical forces by changes in magnetic fields, so the constat fields produced by dc currents won't work at all

Step-by-step explanation: