Gauss’s law should be invalid if

What will be the total flux through the faces of the cube as in figure with side of length $'a'$ if a charge $'q'$ is placed at ?

$(a)$ $C$ $:$ centre of a face of the cube.

$(b)$ $D$ $:$ midpoint of $B$ and $C$.

Consider an electric field $\vec{E}=E_0 \hat{x}$, where $E_0$ is a constant. The flux through the shaded area (as shown in the figure) due to this field is

If the electric field intensity in a fair weather atmosphere is $100 \,V / m$, then the total charge on the earth's surface is ............ $C$ (radius of the earth is $6400\,km$ )

A positive charge $q$ is kept at the center of a thick shell of inner radius $R_1$ and outer radius $R_2$ which is made up of conducting material. If $\phi_1$ is flux through closed gaussian surface $S_1$ whose radius is just less than $R_1$ and $\phi_2$ is flux through closed gaussian surface $S_2$ whose radius is just greater than $R_1$ then:-

A charge $Q$ is fixed at a distance $d$ in front of an infinite metal plate. The lines of force are represented by