Question

A square current carrying loop is suspended in a uniform magnetic field acting in the plane of the loop. If the force on one arm of the loop is $\overrightarrow{F}$, the net force on the remaining three arms of the loop is

• A. $\overrightarrow{F}$
• B. $-3\overrightarrow{F}$
• C. $-\overrightarrow{F}$
• D. $3\overrightarrow{F}$

Answer 1

The correct option is C $-\overrightarrow{F}$

The force on the two arms parallel to the field is zero, since $\overrightarrow{dl}\times \overrightarrow{B}=0$

$\therefore$ Force on remaining arms $=-\overrightarrow{F}$

Since current direction changes for this arm.

Hence, $\left(B\right)$ is the correct answer.