Question

If the electric flux entering and leaving a closed surface are respectively of magnitude ${\varphi }_1$ and ${\varphi }_2$ then the electric charge inside the surface will be

• A. $\frac{{\varphi }_1-{\varphi }_2}{{ϵ}_0}$
• B. $({\varphi }_1-{\varphi }_2){ϵ}_0$
• C. ${ϵ}_0({\varphi }_2-{\varphi }_1)$
• D. ${ϵ}_0({\varphi }_2+{\varphi }_1)$

Answer 1

The correct option is B $({\varphi }_1-{\varphi }_2){ϵ}_0$

Gauss law is

$\frac{q_{in}}{{ϵ}_o}$= ${\varphi }_{net}$

${\varphi }_{net}={\varphi }_1-{\varphi }_2$

so, q= (${\varphi }_1-{\varphi }_2$)${ϵ}_o$