Question

The electric flux passing through $a$ cube of side $a$ , which holds a charge $q$ at one of its corners is

• A. $\frac{q}{\varepsilon_{0}}$
• B. $\frac{q}{8\varepsilon_{0}}$
• C. $\frac{q}{4\varepsilon_{0}}$
• D. $\frac{q}{2\varepsilon_{0}}$

Answer 1

Answer: (B)

$\frac{q}{8\varepsilon_{0}}$

Answer 2

Eight identical cubes are required so that the given charge $q$ appears at the centre of the bigger cube
Thus, the electric flux passing through the given cube is
$\phi=\frac{1}{8} \left(\frac{q}{\varepsilon_{0}}\right)$
$=\frac{q}{8\varepsilon_{0}}$