Practice question · Multiple choice
A transformer changes voltage using no moving parts and cannot work on direct current. Why does DC defeat it?
Hints
- Faraday's law relates induced voltage to the RATE of change of flux. What is that rate for steady DC?
- Ask what alternating current supplies that direct current does not.
Show the answer
C. Because induction responds to a changing flux, and DC is steady
Why
Faraday's law pays for change, and DC offers none, steady flux induces nothing. That single fact settled the war of the currents: AC could be transformed to high voltage for efficient transmission and back down for use, and DC could not, which is why the grid is AC.
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