Problem

Two long straight wires, each carrying a current

I

in opposite directions are separated by a distance

R

. The magnetic induction at a point mid-way between the wires is (a) zero (b)

\frac{\mu_0 I}{\pi R}

(c)

\frac{2\mu_0 I}{\pi R}

(d)

\frac{\mu_0 I}{4\pi R}