A charge $q$ is placed at the centre of the open end of cylindrical vessel. The flux of the electric field through the surface of the vessel is

Careful measurement of the electric field at the surface of a black box indicates that the net outward flux through the surface of the box is $8.0 \times 10^{3} \;Nm ^{2} / C .$

$(a)$ What is the net charge inside the box?

$(b)$ If the net outward flux through the surface of the box were zero, could you conclude that there were no charges inside the box? Why or Why not?

The electric flux passing through the cube for the given arrangement of charges placed at the corners of the cube (as shown in the figure) is 

The electric field in a region of space is given by, $\overrightarrow E  = {E_0}\hat i + 2{E_0}\hat j$ where $E_0\, = 100\, N/C$. The flux of the field through a circular surface of radius $0.02\, m$ parallel to the $Y-Z$ plane is nearly

A charge $Q\;\mu C$ is placed at the centre of a cube, the flux coming out from any surfaces will be

Total electric flux coming out of a unit positive charge put in air is