A potential difference of $1\mathrm{.}30$ V will be applied to a $49\mathrm{.}0$ m length of $18-$gauge copper wire $($diameter $=0\mathrm{.}0400$ in$.).$ Calculate the following values.

$($a$)$ the current

A

$($b$)$ the magnitude of the current density

A$/$m$2$

$($c$)$ the electric field

V$/$m

$($d$)$ the rate at which thermal energy will appear in the wire

W