Two long parallel wires are at a distance 2d apart. They carry steady equal currents flowing out of the plane of the paper as shown. The variation of the magnetic field B along the line XX¹ is given by

The magnetic field in between will be zero because magnetic field due to both wires will be in opposite direction.
$\begin{array}{l}{\mathrm{B}}_{\mathrm{in} \mathrm{between} }=\frac{{\mathrm{\mu }}_0\mathrm{i}}{2\mathrm{\pi x}}\widehat{\mathrm{j}}-\frac{{\mathrm{\mu }}_0\mathrm{i}}{2\mathrm{\pi }(2\mathrm{d}-\mathrm{x})}(-\widehat{\mathrm{j}})\\ {\mathrm{B}}_{\mathrm{in} \mathrm{between} }=\frac{{\mathrm{\mu }}_0\mathrm{i}}{2\mathrm{\pi x}}\left(\frac{1}{\mathrm{x}}-\frac{1}{(2\mathrm{d}-\mathrm{x})}\right)\widehat{\mathrm{j}}\end{array}$
at x = d, B_{in between} = 0
for x < d, B_{in between} $=\widehat{\mathrm{j}}$
for x > d, B_{in between} $=-\widehat{\mathrm{j}}$
towards ' x ' net magnetic field will add up and direction will be $\left(-\widehat{\mathrm{j}}\right)$ .
towards ' x ' net magnetic field will add up and direction will be $\left(-\widehat{\mathrm{j}}\right)$ .