5) Find the electrostatic Potential on the axis z of a hollow Cylinder. v (r=0,z), (0<r<a) the lateral surface of which is maintained at v(r=a,z) = 0 at (o<z<c), v(r=a,z) (0<z<L) and the ends have potentials v

Perhaps you tried to copy and paste a drawing. If so, that does not work on this site. As it is I can not figure out what you mean.