d
(d)At point P net magnetic field \({B_{net}} = \sqrt {B_1^2 + B_2^2} \)

where \({B_1} = \frac{{{\mu _0}}}{{4\pi }}.\frac{{2M}}{{{d^3}}}\) and \({B_2} = \frac{{{\mu _0}}}{{4\pi }}.\frac{M}{{{d^3}}}\)

\( \Rightarrow {B_{net}} = \frac{{{\mu _0}}}{{4\pi }}.\frac{{\sqrt 5 M}}{{{d^3}}}\)