A charged ring of radius a is placed such that its plane lies in the y-z plane and its center coincides with the origin. It carries a line charge density λ = sinθ, with θ being the usual azimuthal angle measured with respect to the x-axis. The scalar potential V at a far away point r behaves as:
Select one: 0 ~ 1/r^2
0 ~ 1/r^4
0 ~ 1/r^3
0 ~ 1/r