A current 1 flows along a triangle loop having sides of equal length a. The strength of magnetic field at the centre of the loop is :

Options

A. `(3mu_0I)/(2pia)`
B. `(9mu_0I)/(2pia)`
C. `(3sqrt3mu_0I)/(2pia)`
D. `(3mu_0I)/(4pia)`

Answer

B

Explanation

The magnetic field at the centroid (or circumcentre) because of side A B of triangular loop is

`mu_0/(4pi)(i(sin60^@+sin60^@))/(a/(2sqrt3))=(3mu_0I)/(2pia)`
hence the net magnetic field due to all 3 sides is `3 xx(9mu_0I)/(2pia)`