Question

A circular coil of wire carries a current PQ is a part of a very long wire carrying a current and passing close to the circular coil. If the direction of the current are those as shown, what is the direction of force acting on PQ?

(1) Parallel to PQ towards P
(3) At right angles to PQ to the right
(2) Parallel to PQ towards Q
(4) At right angles to PQ to the left
fold​

Answer 1

Explanation:

There is a circular coil which is a dipole placed in a non uniform magnetic field due to PQ. Now magnetic field due to circular coil will be out of the plane and not uniform. Therefore, force which will act on PQ will have direction,

F=dl×B

since dl is vertically downwards and B is out of the plane therefore, direction of F will be towards left that is perpendicular to the PQ. or right angled with PQ.

Therefore, option(D)