Question

An electric flux of -5 X 10^-3 Nm²/C passes through a spherical Gaussian surface of radius 20 cm due to a charge placed at its centre.
Calculate the charge enclosed by the Gaussian surface.
If the radius of the gaussian surface is doubled how much flux will pass through the surface?

Answer 1

$$\begin{gathered} flux=chargeenclosed/{\epsilon }_0 \\ chargeenclosed=flux\times {\epsilon }_0=-5\times {10}^{-3}\times 8.85\times {10}^{-12}=44.2\times {10}^{-15}C \end{gathered}$$
Flux is independent of the radius of the gaussian surface.