Question

At the center of a sphere of radius 0.5m a point charge of 2 nC is placed. What electric flux is passing through the sphere?

Answer 1

The Gauss' law says

$$\phi=\oint EdA=\frac{q}{\epsilon_0}$$

$$\phi=\frac{2*10^{-9}}{8.85*10^{-12}}=226\:\rm N\cdot m^2/C$$