Two long parallel wires are at a distance ` 2d` apart. They carry steady equal currents flowing out of the plane of the paper , as shown. The variation of the magnetic field `B` along the line `XX` is given by

Options

A.
B.
C.
D.

Answer

b

Explanation

Both the wires carry equal current in the same direction. Hence, magnetic field at the centre between them will be zero. The direction of magnetic field is opposite on both sides of this null point. Moreover, the direction of magnetic field on both the sides of wires should be opposite to each other. Magnetic field due to a straight current wire is inversely proportional to the distance. Hence, option(b) is correct.