$25\mathrm{.}51$ An electrical conductor designed to carry large currents has a circular cross section $2\mathrm{.}50$ mm in diameter and is $14\mathrm{.}0$ m long. The resistance between its ends is

$0\mathrm{.}104$

$$

$$

$.$

$($a$)$ What is the resistivity of the material? $($b$)$ If the electric$-$field magnitude in the conductor is

$1\mathrm{.}28$

$$

V

$/$

m$,$

what is the total current? $($c$)$ If the material has

$8\mathrm{.}5$

$$

$10$

$28$

free electrons per cubic meter, find the average drift speed under the conditions of part $($b$).$