In the figure,a C-shaped conductor is in a uniform magnetic field B,which is increasing.The polarity of the induced emf in terminals X and Y is
A)X and Y are at the same potential.
B)X is positive and Y is negative.
C)X is negative and Y is positive.

Question

In the figure,a C-shaped conductor is in a uniform magnetic field B,which is increasing.The polarity of the induced emf in terminals X and Y is 
A)X and Y are at the same potential. 
B)X is positive and Y is negative. 
C)X is negative and Y is positive.

Quizplus · Accepted Answer

By Faraday's law of electromagnetic induction, an emf is induced in the conductor when the magnetic field through the conductor changes. In this case, the magnetic field is increasing, so the induced emf generates a current that creates a magnetic field in the opposite direction of the original field. By Lenz's law, the direction of the induced emf is such that it opposes the change in the magnetic field. As the magnetic field increases, the induced emf will generate a current that creates a magnetic field pointing into the page, in the same direction as the original magnetic field. By the right-hand rule for current, the direction of the current is counterclockwise, so terminal X will become negative and terminal Y will become positive. Therefore, the correct choice is C.

In the Figure,a C-Shaped Conductor Is in a Uniform Magnetic