A circular loop of area `1cm^2` , carrying a current of 10 A , is placed in a magnetic field of 0.1 T perpendicular to the plane of the loop. The torque on the loop due to the magnetic field is

Explanation

The given arrangement of circular coil and magnetic field is shown below:

Here, the coil is lying in XY-plane and the magnetic field is along the Z-axus.
If we consider a small element `d vecl ` of the oil, then the force acting on this element due to magnetic field will be,
` F = Idvecl xx vecB` . For each element `d vecl` , there is another element `-d vecl` on the circuar loop, Force acting on such element will be `F = - I vec(dl) xx vecB` .
` :. ` Force ` vecF` on one element segment of coil will counter balance the force `vecF`. on another diametrically opposite element. Similarly, we can calculate the force for other elements and it can be concluded that, there will be no net force on the circular coil. From the figure, as `hatn " and "vecB` are along the same direction, angle between them,`theta = 0^(@)`.
` :. ` Torque acting on the coil will be zero.