Gauss's law is true only if the force due to a charge varies as:

$A$ uniform electric field $E = 3 \times 10^5 \text{ NC}^{-1}$ is acting along the positive $Y$-axis. The electric flux through a rectangle of area $10 \text{ cm} \times 30 \text{ cm}$ whose plane is parallel to the $ZX$-plane is

Select the correct statement$(s)$.
$(1)$ The tangent drawn at any point on an electric field line gives the direction of the force acting on a positive charge at that point.
$(2)$ The normal drawn at any point on an electric field line gives the direction of the force acting on a positive charge at that point.
$(3)$ Electric field lines start from a negative charge and end on a positive charge.
$(4)$ Electric field lines start from a positive charge and end on a negative charge.

If an electric field is given by $\vec{E} = 10 \hat{i} + 3 \hat{j} + 4 \hat{k}$,calculate the electric flux through a surface of area $A = 10 \text{ units}$ lying in the $yz$-plane.

$A$ charge $q$ is located at the centre of a cube. The electric flux through any face is

$C_1$ and $C_2$ are two hollow concentric cubes enclosing charges $2Q$ and $3Q$ respectively as shown in the figure. The ratio of electric flux passing through $C_1$ and $C_2$ is: