Question

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

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

Answer 1

Answer: (A)

From Gauss theorem, the electric flux $(\varphi )$ through any closed surface is equal to $\frac{1}{{\epsilon }_0}$ times the net charge $q$ enclosed by the surface. Thus,

$\varphi =\int \vec{E}\cdot d\vec{A}=\frac{q}{{\epsilon }_0}$