Why electric flux is zero in a closed surface?

If there is no net charge within a closed surface, every field line directed into the surface continues through the interior and is directed outward elsewhere on the surface. The negative flux just equals in magnitude the positive flux, so that the net, or total, electric flux is zero.

Is it possible to have a net flux of zero through a closed surface?

The flux through the closed surface will be zero only if the charge enclosed by the surface is zero. According to Gauss theorem, flux of a electric field through a closed surface is always zero if there is no net charge in the volume enclosed by the surface.

When the electric flux through a closed surface is zero then the net charge inside the surface must be zero?

As the flux is zero through the surface, the charge enclosed must be zero.

What can you say about the charge enclosed by the closed surface if flux through it is zero *?

Gauss’s law tells us that the electric flux through a closed surface is proportional to the net charge enclosed by the surface. Thus, the electric flux through the closed surface is zero only when the net charge enclosed by the surface is zero.

What is charge enclosed?

The charge enclosed in the sphere is then equal to the electric flux density on its surface times the area enclosing the charge. The lines of flux contributing to the flux density are those that leave the sphere perpendicular to the surface of the sphere.

What is the charge enclosed by closed surface?

The net electric flux through any closed surface surrounding a net charge ‘q’ is independent of the shape of the surface. 3. The net electric flux is zero through any closed surface surrounding a zero net charge. Therefore, if we know the net flux across a closed surface, then we know the net charge enclosed.

What is the net charge enclosed by the Gaussian surface?

zero
It is immediately apparent that for a spherical Gaussian surface of radius r < R the enclosed charge is zero: hence the net flux is zero and the magnitude of the electric field on the Gaussian surface is also 0 (by letting QA = 0 in Gauss’s law, where QA is the charge enclosed by the Gaussian surface).