Question

The energy stored in the electric field produced by a metal sphere is 4.5 j. if the sphere contains 4 µc charge, its radius will

Answer 1

Energy of sphere = $\frac{Q^2}{2C}$$\begin{align*}4.5 &= \frac{16 \times 10^{-12}}{2C} \\ C & =\frac{16 \times 10^{-12}}{9} = 4\pi \in_0 R \\ R & = \frac{16 \times 10^{-12}}{9}\times \frac{1}{4 \pi \in_0} \\ & = 9 \times 10^9\times \frac{16}{9} \times 10^{-12} \\ & = 16\times 10^{-3} \\ & =16 mm \end{align*}$.I hope this answer is helpful to you