Q149 / 180 · AIIMS 2001 · Physics

A charge is placed at the centre of cube of side $a$ then flux linked with one of its given faces will be

A
$\frac{Q}{\varepsilon_0}$
Correct answer
B
$\frac{Q}{6 \varepsilon_0}$
C
$\frac{Q}{\varepsilon_0 a^2}$
D
$\frac{Q}{4 \pi \varepsilon_0 a^2}$.

Solution

Gauss's law tells that the total flux through an area enclosing a charge $Q$ is $\frac{Q}{\varepsilon_0}$. Now as the cube is having six faces and as we can assume a symmetrical distribution of fluxes among its faces, the flux associated with one of its faces is $\frac{Q}{6 \varepsilon_0}$.

Hence, the correct answer is option: 'B'.

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