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 in to the page

Answer

B

Explanation

B due to Arc = `(mu_(0) I theta)/( 4pi r) implies (mu_(0) I)/(8) ((1)/(r ) - (1)/( R))` out of the page