Acurrent i flows down a wire of radius a.
(a) if it is uniformly distributed over the surface, what is the surface current density k?
(b) if it is distributed in such a way that the volume current density is inversely.

(a)

(b)

Explanation:

(a) The surface current density of a conductor is the current flowing per unit length of the conductor.

Considering a wire, the current is uniformly distributed over the circumferenece of the wire.

The radius of the wire = a

The surface current density

(b) The current density is inversely proportional

                                                ......(1)

k is the constant of proportionality

                                          ........(2)

substituting (1) into (2)

substitute

gas and liquid