DC current is flowing in the primary coil of a transformer.
Choice-D is the one that does NOT happen.
A. There is a magnetic field in the primary.
Yes, just as there is around EVERY current-carrying conductor.
B. Current flows in the primary.
Yes. The first sentence says so.
C. The primary gets warm.
Yes. Just like ANY current-carrying conductor that has any resistance.
D. Current flows in the secondary
NO. Current in the secondary is the result of CHANGES in the primary current. Since the primary current is DC, there aren't any changes.
A long time ago, in engineering school in a galaxy far away, I learned that when you put DC into a transformer, what comes out is smoke.
