Question

A coil of area 0.01 m${}^2$ is lying in a perpendicular magnetic field of 0.1 Tesla. If a current of 10 A is passed in it then the maximum torque acting on the coil will be

• A. 0.01 N/m
• B. 0.001 N/m
• C. 1.1 N/m
• D. 0.8 N/m

Answer 1

The correct option is A 0.01 N/m

Magnetic moment = $I\overrightarrow{A}=0.01\times 10A/m^2$ perpendicular to the field.
Maximum torque on the magnetic moment is when angle between magnetic moment and the field is ${90}^{\circ }=\left(I\overrightarrow{A}\right)\times \overrightarrow{B}=IAB=10\times 0.01\times 0.1=0.01Nm$