Question

A current I flows down a wire of radius a.

Answer 1

Answer:

Part a)

$K = \frac{I}{\pi a^2}$

Part b)

$J(s) = \frac{CL}{r}$

here we know that L = length of the wire

Explanation:

Part a)

Current density is given as

$K = \frac{I}{A}$

$K = \frac{I}{\pi a^2}$

since current is uniformly divided across the crossection of the wire so it is given as

$K = \frac{I}{\pi a^2}$

Part b)

As we know that volume current density is inversely proportional to the distance from the axis

So we will have

$\frac{I}{\pi r^2 L} = \frac{C}{r}$

so we have

$J(s) = \frac{CL}{r}$

here we know that L = length of the wire