Question

A square loop of wire is placed in a magnetic field as shown below.
If the direction of current flow is clockwise, what is the direction of the net torque and motion of the loop?

• A. Up the page.
• B. Down the page.
• C. To the left.
• D. To the right.
• E. The net torque is zero.

Answer 1

Answer: (E)

The net torque is zero.

Torque acting on the loop $\tau =I(\overrightarrow{A}\times \overrightarrow{B})=IAB$ $sin\theta$

Direction of the current flowing in the loop is clockwise, this implies that the area vector of the loop points into the plane of paper.

$⟹$ Angle between $\overrightarrow{A}$ and $\overrightarrow{B}$ is zero i.e $\theta =0^o$

$\therefore$ Torque on the loop $\tau =IAB\times 0=0$