A straight wire lies along the y-axis initially carrying a current of 10 A in the positive y-direction.The current decreases and reverses to 10 A in the negative y-direction,the change in current happening at a uniform rate.In the 1st quadrant a square conducting coil has 2 sides parallel to the y-axis and the other 2 sides parallel to the x-axis.The side of the coil nearest and parallel to the straight wire is at a distance equal to the length of one of the sides of the square.As the current is going from 10 A in one direction to 10 A in the other,in which direction is the induced current in this side of the square coil nearest to the straight wire?
A)It is in the positive y-direction.
B)It is in the negative y-direction.
C)At first it is in the positive y-direction,but after the current passes through zero,it is in the negative y-direction.
D)At first it is in the negative y-direction but after the current passes through zero,it is in the positive y-direction.

Question

Quizplus · Accepted Answer

The magnetic field due to the straight wire is in the positive x-direction. As the current decreases, the magnetic field decreases, inducing an emf in the coil. The direction of the induced current is such that it creates a magnetic field that opposes the change in the original magnetic field. Therefore, the induced current in the side of the coil nearest to the straight wire is in the positive y-direction.

A Straight Wire Lies Along the Y-Axis Initially Carrying a Current