Sketch the electric field lines for a uniformly charged hollow cylinder shown in figure.

$q_1, q_2, q_3$ and $q_4$ are point charges located at point as shown in the figure and  $S$ is a spherical Gaussian surface of radius $R$. Which of the following is true  according to the Gauss's law 

Figure shows the electric lines of force emerging from a charged body. If the electric field at $A$ and $B$ are ${E_A}$ and ${E_B}$ respectively and if the displacement between $A$ and $B$ is $r$ then

As shown in figure, a cuboid lies in a region with electric field $E=2 x^2 \hat{i}-4 y \hat{j}+6 \hat{k} \quad N / C$. The magnitude of charge within the cuboid is $n \varepsilon_0 C$. The value of $n$ is $............$ (if dimension of cuboid is $1 \times 2 \times 3 \;m ^3$ )

A charged particle $q$ is placed at the centre $O$ of cube of length $L$ $(A\,B\,C\,D\,E\,F\,G\,H)$. Another same charge $q$ is placed at a distance $L$ from $O$.Then the electric flux through $BGFC$ is

A charge $+q$ is placed somewhere inside the cavity of a thick conducting spherical shell of inner radius $R_1$ and outer radius $R_2$. A charge $+Q$ is placed at a distance $r > R_2$ from the centre of the shell. Then the electric field in the hollow cavity