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**Q)An infinitely long current carrying wire , carrying current I moving towards positive Y is placed along Y-axis. In the X-Y plane , a circular loop of radius 'r' is placed at a distance 'r' from the wire carrying current 'i' in anticlockwise circulation. Find the force exerted by the infinite wire on the loop.**

## Homework Equations

Acc. to me the only equation required should be

dF=i {dlxB} where B is the magnetic field due to the infinitely long wire at the length element dl which is to be integrated .

## The Attempt at a Solution

dF=i{dlxB}

dF= (i*U*I/2pi) * 1/r *dl (assuming dl to be a small length element on the loop.

where r is the distance of dl.

i replaced dl by rd$ where $ is the small angle and now wished to integrate along $ from 0 to 2pi but B has a dependence on 'r' only as it decreases along X axis. so i am stuck on how to integrate B along with d$.