Question

A conductor carrying direct current is split into a circular loop (Fig.). What is the force acting on a magnetic pole placed at the centre O of the loop?

Answer 1

Answer:  F = 0.

Explanation:

All current elements in the branched circuit are distributed quite symmetrically with respect to point O. To each small element A (Fig.) there corresponds another element B parallel to A, which has current in the same direction as A, but passes at the same distance from O on the other side. The magnetic field intensities due to elements A and B are of the same magnitude, but of opposite direction, and thus cancel each other.