Question

the principle by which an alternator changes mechanical energy into electrical energy is called
a. electromotive force.
b. electromagnetic induction.
c. electronic resistance.
d. electrical energy.
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Explanation:

An alternator operates based on the principle of electromagnetic induction. Electromagnetic induction is the process where a conductor moving in a magnetic field (or a changing magnetic field around a conductor) induces an electromotive force (emf) in the conductor, thus converting mechanical energy (from the motion of the conductor or the change in the magnetic field setup) into electrical energy.

• Electromotive force (emf): It is just the voltage or potential difference induced. It is not the principle of energy conversion.
• Electrical resistance: It is a property of a material that opposes the flow of electric current. It has no relation to the energy - conversion principle in an alternator.
• Electrical energy: This is the end - product of the conversion in an alternator, not the principle by which the conversion occurs.

Answer:

B. electromagnetic induction