Question

A charge $Q$ is placed at the corner of a cube. The electric flux through all the faces of the cube is:

• A. $Q/{\epsilon }_0$
• B. $Q/6{\epsilon }_0$
• C. $Q/8{\epsilon }_0$
• D. $Q/3{\epsilon }_0$

Answer 1

Answer: (C)

$Q/8{\epsilon }_0$

Let us add 7 more cubes of same size as above and make $Q$ placed at center of large cubes with side 2a.
Now there are 8 cubes covering $Q$.

So, flux coming out will be divided equally as $Q$ is symmetrically placed.
$\therefore$ flux through any one of the cubes $=\frac{Q}{8{\xi }_0}$