Which statement about alternators and generators is correct?

• A. An alternator generates AC power; a generator can generate AC or DC power.
• B. An alternator generates DC power; a generator generates AC power.
• C. Both generate AC power, but the alternator is more common in vehicles.
• D. An alternator produces DC power; a generator produces DC as well.

Answer: (A)

The main idea here is the kind of electrical power produced by rotating machines and how DC is obtained when needed. An alternator is designed to produce alternating current directly. In many practical uses, especially in cars, that AC is then converted to direct current by diodes so it can charge the battery and run the electrical system. A generator, in general, can be built to produce either AC or DC depending on its design: an AC generator gives AC directly, while a DC generator uses a commutator to deliver DC. So the statement matches the fundamental distinction: the alternator produces AC, and a generator can produce either AC or DC.