#### Answer

$\Delta V = 0.87~V$

#### Work Step by Step

We can find the resistance:
$R = \frac{\rho~L}{A}$
$R = \frac{\rho~L}{\pi~r^2}$
$R = \frac{(1.7\times 10^{-8}~\Omega~m)(20~m)}{(\pi)~(1.0\times 10^{-3}~m)^2}$
$R = 0.1082~\Omega$
We can find the potential difference:
$\Delta V = I~R$
$\Delta V = (8.0~A)(0.1082~\Omega)$
$\Delta V = 0.87~V$