Question

A uniformly changed sphere of radius 1 cm has potential of 8000 V at surface. The energy density near the surface will be:

• A. $64\times {10}^{5}J/m^3$
• B. $8\times {10}^{3}J/m^3$
• C. $32J/m^3$
• D. $2.83J/m^3$

Answer 1

The correct option is D $2.83J/m^3$

Energy density $=\frac{Energy}{volume}=\frac{1}{2}{\epsilon }_0{E}^2$

$E_D=\frac{1}{2}\times 8.85\times {10}^{-12}\times \frac{{8000}^2}{{10}^{-4}}=2.832J/m^3$