Question

A charge $Q$ is placed just outside a closed hemisphere of radius $r$ as shown in the figure. Find the total flux associated with the hemisphere.

• A. Zero
• B. $\frac{Q}{{\epsilon }_0}$
• C. $\frac{Q}{2{\epsilon }_0}$
• D. None of the above

Answer 1

The correct option is A Zero


Since, the number of field lines entering into the hemisphere is equal to the number of field lines exiting the closed surface.
So, net flux through the surface will be zero. i.e.,
${\varphi }_{\text{net}}=0$

Hence, option (a) is correct answer.

$\text{Key Point:}$ For any charge located outside a closed surface the net flux through the surface is always zero irrespective of the shape of the closed surface.