Could you just explain this problem. A bar magnet is held stationary while a cir

Question

Could you just explain this problem.

A bar magnet is held stationary while a circular loop of wire is moved toward the magnet at constant velocity at position A as in the figure below. The loop passes over the magnet at position B and moves away from the magnet at position C. (For the following questions, state the directions as if you were to the right of the magnet, watching the loop of wire move away from you.)

(a) Find the direction of the induced current in the loop using Lenz's law at position A. answer: counterclockwise

(b) Find the direction of the induced current in the loop using Lenz's law at position C. answer: clockwise

(c) What is the induced current in the loop at position B? (Position B has the center of the loop exactly at the midpoint of the bar magnet. answer: no current is induced.

Explain:

Explanation / Answer

a)

at A the loop is moving toward the barmagnet,

here,

the loop is approaching the south pole of the magnet

therefore loop should have the noth pole to oppose the southpole of the bar magnet,

hence, the current in the loop is counterclockwise

b)

at B the loop is moving away from the barmagnet,

here,

the loop is moving away from the south pole of the magnet

therefore loop should have the south pole to attract the southpole of the bar magnet,

hence, current in the loop is clockwise

c)

here,

rate of change of flux through the loop is zero

hence, induced current will be zero

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