Answer:[tex]9.6\times 10^{-8} J[/tex]
Explanation:
The capacitance of cylindrical capacitor is
C=[tex]\frac{2\pi \varepsilon _0L}{\ln\frac{r_2}{r_1}}[/tex]
C=[tex]\frac{2\pi \times 8.854\times 10^{-12}\times 150}{\ln\frac{8}{4}}[/tex]
C=[tex]1.2\times 10^{-8} F[/tex]
potential Energy stored in capacitor=[tex]\frac{1}{2}CV^2[/tex]
=[tex]\frac{1}{2}\times 1.2\times 10^{-8}\times 4^2[/tex]
=[tex]9.6\times 10^{-8} J[/tex]
