Question

p45. if more electric field lines leave a gaussian surface than enter it, what can you conclude about the net charge enclosed by that surface?

Explanation:

Relate electric field lines to net electric flux

$$ \Phi_E > 0 $$

Apply Gauss's Law to find the sign of the enclosed charge

$$ \Phi_E = \frac{Q_{\text{enclosed}}}{\varepsilon_0} \implies Q_{\text{enclosed}} > 0 $$

Answer:

The net charge enclosed by the surface is positive.