Two similar coils of radius `R` are lying concentriclaly with their planes at right angels to each other. The currents flowing in them are `I` and `2I` respectively. The resulant magntic field induction at the centre will be

Options

A. `(3mu_0I)/(2R)`
B. `(mu_0 I)/(2R)`
C. `(mu_0I)/(R )`
D. `(sqrt5 mu_0 I)/(2R)`

Answer

D

Explanation

`B = sqrt(B_1^2 + B_2^2) = (mu_0 I)/(2R) sqrt( 1^2 + 2^2) = (mu_0 I sqrt5)/(2R)`