A circular loop of radius a, carrying a current I, is placed in a tow dimensional magnetic field. The centre of the loop coincides with the centre of the filed The strenght of the magnetic field at the pariphery of the loop is B. find the magnetic force on the wire.

Explanation

`F _(dl) = I , (dl xx B) = idLB
(because dl and B are perpndicular to each other )
` (b) 2T sin sin theta = I (dl xx B) `
`= I, 2a sin theta B `
` :. Sin theta is very small , sin sin theta = sin theta `
`2T sin theta = I , 2a sin theta B `
`:. T = iab`