A thin, long, straight wire is surrounded by plastic insulation of radius \(R\) and dielectric constant \(\kappa\) (Figure 26.32). The wire carries a uniform distribution of charge with a positive linear charge density \(\lambda\). If the wire has a diameter \(d\), what is the potential difference between the outer surface of the wire and the outer surface of the insulation?

Data from Figure 26.32

R wire plastic insulation