A single current carrying loop of wire carrying current I flowing in anticlockwise direction seen from +z direction and lying in xy plane is shown in figure. The plot of ĵ component of magnetic field Bᵧ at a distance a (less than radius of the coil) and on yz plane versus z coordinate looks like:

Question

G1 Physics · Accepted Answer

In the plane of the loop, Bᵧ = 0. For points at +z and -z with the same y-coordinate, the y-components of magnetic field are opposite in sign. Therefore the graph must cross zero at z = 0 and change sign across it, corresponding to option 3.