Question

One major advantage of alternating current over direct current is that you can use alternating current with a device known as a transformer. The reason why alternating current works in transformers but direct current does not is?

Answer 1

On USATestprep its D

Answer 2

transformer makes use of mutual induction for its operation in which change in magnetic field in one coil due to variation of current , induces voltage in the other coil. so changing magnetic field in the primary coil is very much needed for the transformer. Alternating current is a current which varies with time , hence it is suitable to produce changing magnetic field in the primary coil. on the other hand , the direct current remains constant all the time. hence can not produce a changing magnetic field. so DC current is not useful for transformers.