Two north poles each of pole strength `m` and a south pole of pole strength `m` are placed at the three corners of an equilateral triangle of side a. The intensity of magnetic induction field strength at the centre of the triangle is

Options

A. `mu_0/(4pi) (m)/(da^2)`
B. `mu_0/(2pi) (3m)/(a^2)`
C. `mu_0/(4pi) (9m)/(a^2)`
D. `mu_0/(4pi) (m)/(2a^2)`

Answer

B