The magnetic field and the number of turns of a coil of wire are doubled, while its area is reduced by a factor of 2. Assuming that all the other parameters remain the same, what happens to the induced emf in that coil of wire?
A) It is doubled.
B) It is reduced by a factor of 2.
C) It is quadrupled.
D) It is reduced by a factor of 4.
E) It stays the same.

Question

Quizplus · Accepted Answer

According to Faraday's Law of Electromagnetic Induction, the induced emf in a coil is proportional to the product of the magnetic field, the number of turns of the coil, and the area enclosed by the coil. Thus, when the magnetic field and the number of turns are doubled, the induced emf is also doubled. However, when the area is reduced by a factor of 2, the induced emf is halved. Thus, the net effect is an increase in the induced emf by a factor of 2, resulting in choice A being the correct answer.

The Magnetic Field and the Number of Turns of a Coil