Consider the four surfaces $S_1, S_2, S_3,$ and $S_4$ enclosing the same charge $q_1$ as shown in the figure. Compare the electric flux through these surfaces.

Three positive charges of equal value $q$ are placed at the vertices of an equilateral triangle. The resulting lines of force should be sketched as in:

Five point charges $\frac{1}{\pi}, \frac{2}{\pi}, \frac{3}{\pi}, \frac{4}{\pi}$ and $\frac{-5}{\pi} \ nC$ are located inside a pyramid. The total electric flux through the surface of the pyramid is

Electric charge is uniformly distributed along a long straight wire of radius $1\, mm$. The charge per $cm$ length of the wire is $Q$ $coulomb$. Another cylindrical surface of radius $50\, cm$ and length $1\, m$ symmetrically encloses the wire as shown in the figure. The total electric flux passing through the cylindrical surface is

Select the correct statement$(s)$:
$(1)$ The density of electric field lines is independent of the magnitude of the electric field vector $E$ at a given point.
$(2)$ The density of electric field lines is proportional to the magnitude of the electric field vector $E$ at a given point.
$(3)$ Electric field lines do not exist in reality. They are only a graphical representation of the electric field.
$(4)$ Electric field lines exist in reality.

$A$ hollow cylinder has a charge $q$ inside it. If $\phi$ is the electric flux associated with the curved surface $B$,the flux linked with the plane surface $A$ will be