Magnetics

A single current carrying loop of wire carrying current I flowing in anticlockwise direction seen from +ve \(\mathrm{z}\) direction and lying in \(x y\) plane is shown in figure. The plot of \(\hat{j}\) component of magnetic field (By) at a distance '\(a\)' (less than radius of the coil) and on \(y z\) plane vs \(z\) coordinate looks like