Question

A conducting circular loop of radius r carries a constant
current i. It is placed in a uniform magnetic field →B₀ such
that →B₀ is perpendicular to the plane of the loop. The
magnetic force acting on the loop is
(a) ir B₀ (b) 2π ir B₀
(c) zero (d) π ir B₀

Answer 1

Answer:

The magnetic field is perpendicular to the plane of the paper. Let us consider two diametrically opposite elements as shown in the figure.Since  the direction of current is opposite, forces will cancel each other due to dF=i(dl×B)

The magnetic field is perpendicular to the plane of the paper. Let us consider two diametrically opposite elements as shown in the figure.Since  the direction of current is opposite, forces will cancel each other due to dF=i(dl×B)

Explanation:

Similarly, all forces acting on the diametrically opposite elements will cancel out in pair. The net force on the loop will be zero.