An arangement with a pair of quarter circular coils of radii r and R with a common centre C and carrying a current I is shown.

The permeability of free space is `mu_(0)`. The magnetic field at C is

Options

A. `mu_0 I (1 //r -1 // R)// 8` into the page
B. `mu_0 I (1 // r - 1//R) //8` out of the page
C. `mu_0 I (1//r + 1//R)//8` out of the page
D. `mu_0 I (1 //r + 1//R)//8` into the page

Answer

B

Explanation

B du to Arc `=(mu_0 itheta )/( r pi r)`
`(mu_(0)i)/(8)[(1)/(r )-(1)/(R ) ]` out of the page