Question

A point charge $+q$ is placed at the centre of a cube of side $L$. The electric flux emerging from the cube is

• A. $\frac{q}{{\epsilon }_0}$
• B. zero
• C. $\frac{6q{L}^2}{{\epsilon }_0}$
• D. $\frac{q}{6L^2{\epsilon }_0}$

Answer 1

The correct option is A $\frac{q}{{\epsilon }_0}$

By Gauss Law,

${\oint }_s\overrightarrow{E}.\overrightarrow{ds}=\frac{Q_{enc}}{{\epsilon }_0}$

Now flux, ${\varphi }_E=$${\oint }_s\overrightarrow{E}.\overrightarrow{ds}$

and, $Q_{enc}=q$

flux, ${\varphi }_E=\frac{q}{{\epsilon }_0}$