Question

Point charges $30C,-20C$ and $10C$ are located at $(-1,0,2),(0,0,0)$ and $(1,5,-1)$ respectively. The total electric flux leaving cube of side $6m$ centered at the origin is

• A. $\frac{-20}{{\epsilon }_0}$
• B. $\frac{10}{{\epsilon }_0}$
• C. $\frac{20}{{\epsilon }_0}$
• D. $\frac{30}{{\epsilon }_0}$

Answer 1

Answer: (B)

Given, point charges $30C,-20C$ and $10C$ are located at $(-1,0,2),(0,0,0)$ and $(1,5,-1)$. Side of the cube $=6m$
As per Gauss' theorem, net electric flux passing through any closed surface
$=\frac{q_{\text{in }}}{{\epsilon }_0}$
Here, $q_{\text{in }}=30-20+10=20C$
$\therefore$ Net electric flux
$=\frac{q}{{\epsilon }_0}=\frac{10}{{\epsilon }_0}$