Question

A rectangular loop of wire with dimensions shown in figure is coplanar with a long wire carrying current $I$. The distance between the wire and the left side of the loop is pulled to the right as indicated. What are the directions of the induced current in the loop and the magnetic forces on the left and the right sides of the loop when the loop is pulled?

• A. Induced current-Counterclockwise; Force on left side-To the left; Force on right side-To the left
• B. Induced current-Counterclockwise; Force on left side-To the right; Force on right side-To the left
• C. Induced current-clockwise; Force on left side-To the right; Force on right side-To the left
• D. Induced current-Counterclockwise; Force on left side-To the left; Force on right side-To the right
• E. answer required

Answer 1

Answer: (D)

Induced current-Counterclockwise; Force on left side-To the left; Force on right side-To the right

Field due to the current will be directed coming out the paper as shown.
When the loop is pulled away, flux decreases. By Lenz's law a current in the anticlockwise direction will be induced such that it opposes the decreases in flux.
Therefore force of left side would be given by $\overrightarrow{I}\times B$ , towards left.
Therefore force of right side would be given by $\overrightarrow{I}\times B$ , towards right.