(a) briefly describe the physical origin of bound currents in magnetised materials consider a thin slab of material with uniform magnetisation m. with the aid of a diagram and a qualitative argument, show that the volume bound current density is [5] 3. zero (b) a thin conducting cylindrical shell (or pipe) of radius a and infinite extent is symmetrical about the z-axis. it is surrounded by a linear magnetic material extending out to a cylindrical radius b in which the magnetic susceptibility varies smoothly with cylindrical coordinate as xm(s)= xoa2/s2 for a < s