The magnetic field existing in a region is gicen by `vecB =B_0(1+(x)/(l))vec k.` A square loop of edge l and carrying a current I, is placed with its edges parallel to the x-y axes. Find the magnitude of the net magnetic force experienced by the loop.

Options

A. `2B_(0)li`
B. `0`
C. `B_(0)li`
D. `4B_(0)li`

Answer

C

Explanation

`F_(bc)+F_(da)=0`

Force, `F_(ab)=ilB_(0)(1+(x)/(l))=iB_(0)l+iB_(0)x" "` (towards right)
Force `F_(cd)=ilB_(0)[1+(x+l)/(l)]=2iB_(0)l+iB_(0)x" "` (towards left)
`:.F_("net")=F_(cd)-F_(ab)=iB_(0)l" "` (towards left)