The plates of the capacitor have equal & opposite charge which cancels out each other.The net charge enclosed is zero. Hence, the net flux will be zero.

Explanation:

When a capacitor of capacitance c is charged to a potential v, it creates an electric field between its plates. This electric field is responsible for the energy stored in the capacitor.

Electric Flux:

Electric flux is the measure of the electric field passing through a given area. If the electric field lines pass through a surface, then the electric flux is positive. If the electric field lines leave the surface, then the electric flux is negative. If the electric field lines pass perpendicular to the surface, then the electric flux is maximum.

Closed Surface:

A closed surface is a surface that encloses a certain volume. The electric flux through a closed surface is zero because the electric field lines entering the surface are equal to the electric field lines leaving the surface. The electric field lines that enter the surface are positive, and the electric field lines that leave the surface are negative. As a result, the electric flux through the closed surface is zero.

Capacitor Inside Closed Surface:

When a charged capacitor is placed inside a closed surface, the electric flux passing through the surface is zero. The electric field lines generated by the charged capacitor are contained within the capacitor plates. Therefore, the electric field lines do not pass through the closed surface. As a result, the electric flux through the closed surface is zero.

Conclusion:

In conclusion, the electric flux through a closed surface is zero when a charged capacitor is placed inside it. This is because the electric field lines generated by the charged capacitor are contained within the capacitor plates and do not pass through the closed surface.