Chapter 25, Problem 25.65AP

From Gauss's law, the electric field set up by a uniform line of charge is

$\stackrel{\to }{\text{E}}=\left(\frac{\lambda }{2\pi {\in }_{0}r}\right)\hat{\text{r}}$

where r is a unit vector pointing radially away from the line and λ is the linear charge density along the line. Derive an expression for the potential difference between r = r₁, and r = r₂.