Question

A loop $PQR$ carries a current of $2A$ as shown. A uniform magnetic field $(B=2T)$ is parallel to plane of the loop. The magnetic torque on the loop is:

• A. $16Nm$
• B. $8Nm$
• C. Zero
• D. $4Nm$

Answer 1

The correct option is B $8Nm$

Given,
current in the loop $\left(i\right)=2$
magnetic field $\left(B\right)=2T$
Area of loop $\left(A\right)=\frac{1}{2}\times Base\times Height$
$=\frac{1}{2}\times PR\times PQ=\frac{1}{2}\times 2\times 2=2m^2$
We know that,
magnetic torque $\left(\tau \right)=iAB\sin \theta$ [Here, $\theta ={90}^{\circ }]$
$=2\times 2\times 2\times \sin {90}^{\circ }$
$=2\times 2\times 2\times 1=8Nm$.