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

A

Explanation

The magnetic field in between because of each will be in opposite direction
`:. B_("in between")=(mu_(0)i)/(2pix) j - (mu_(0)j)/(2pi(2d-x))(-j),=(mu_(0)j)/(2pi)[1/x-1/(2d-x)](j)`
At x=d, `B_("in between")=0,` For `x lt d, B_("in between")=(j),` For `xgtd, B_("in Between")=(-j)`
Towards x, net magnetic field will add up and direction will be (–j)
Towards , net magnetic field will add up and direction will be (j)