Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (4th Edition)

$\phi_{a}=\frac{q}{\epsilon_0}$ $\phi_{b}=-\frac{q}{\epsilon_0}$ $\phi_{c}=0$
Flux through a body due to charges present outside is 0. So, there will be flux only due to charges present inside the body. 1.Charge in figure (a) $=q$ so, electric flux through $\phi_{a}=\frac{q}{\epsilon_0}$ 2. Charge in figure (b) $=-q$ so, electric flux through $\phi_{b}=-\frac{q}{\epsilon_0}$ 3. Charge in figure (c) $=0$ so, electric flux through $\phi_{c}=0$ Hence, $\phi_{a}=\frac{q}{\epsilon_0}$ $\phi_{b}=-\frac{q}{\epsilon_0}$ $\phi_{c}=0$