Answer
The potential difference between points 2 and 3 is $~~10~V$
Work Step by Step
We can find the resistance of Wire D:
$R = \frac{\rho~L}{A}$
$R = \frac{\rho~L}{\pi~r^2}$
$R = \frac{(1.0\times 10^{-6}~\Omega \cdot m)(1.0~m)}{(\pi)~(2.5\times 10^{-4}~m)^2}$
$R = 5.09~\Omega$
We can find the potential difference:
$\Delta V = i~R$
$\Delta V = (2.0~A)(5.09~\Omega)$
$\Delta V = 10~V$
The potential difference between points 2 and 3 is $~~10~V$
