Question

Several questions about the direction of induced current. In all the parts of this question, the same initial situation holds, shown in the figure. In the heavy loop there is a clockwise current. Something about the arrangement is changing, and a current may or may not be induced in the lighter loop as a result. For each part, specify whether the induced current runs clockwise, counterclockwise, or if no current is induced at all. The current in the heavy loop is increased, The heavy loop is pulled away to the left, The heavy loop is rotated: its top side is lifted and the bottom is sunk so that the loop lies in a plane perpendicular to the page, and the current is coming out of the page at the left, running over the top from left to right, and diving into the page on the right, The heavy loop is cut so the current stops flowing, The heavy loop and its current is unchanged, but the lighter loop is crushed so it becomes smaller in diameter.

Answer 1

The magnetic field due to the heavy loop is always along its axis. The flux through the lighter loop should be changed to induce the current in it. In option (a), the flux through the lighter loop is constant. Thus, no induced current will be in the lighter loop.

(b)

In this case, the flux decreases along into the page. So, the current in the lighter loop will be clockwise.

(c)

In this case, no flux passes through the lighter loop and induced current is zero.

(d)

In this case, the induced current in the light loop is clockwise.

(e)

In this case, the induced current is in counterclockwise direction.