Question

A conducting loop carrying a current $I$ is placed in a uniform magnetic field pointing into the plane as shown in the figure. The loop will have tendency to

• A. contract
• B. expand
• C. move towards positive x-axis
• D. move towards negative x-axis

Answer 1

The correct option is B expand

As
$\overrightarrow{F}=I(\overrightarrow{l}\times \overrightarrow{B})$
As $\overrightarrow{l}$ is along the length (tangential)
and $\overrightarrow{B}$ is inwards,Using Righthand thumb rule
$\overrightarrow{F}$ should be normal and away from centre of the loop.
So,the loop expands.