As shown in the figure,a straight wire carries a current I into the page.The wire passes through the center of a toroidal coil.If the current I is quickly reduced to zero,the direction of the induced current through the resistor R is

Question

Quizplus · Accepted Answer

As we reduce the current I to zero, the magnetic flux passing through the toroidal coil will change. According to Faraday's Law, this change in flux will induce an electromotive force (EMF) in the coil. The direction of the induced EMF can be found using Lenz's Law, which states that the induced current flows in a direction so as to oppose the change in flux that produces it. In this case, the current is being reduced, so the induced current will flow in a direction to maintain the original magnetic field. By applying the right hand rule, we can see that the induced current will flow clockwise when viewed from the top of the toroid. This means that the current through the resistor R will be from b to a. Therefore, the correct choice is B.

As Shown in the Figure,a Straight Wire Carries a Current