A square of side $a$ is lying in $xy$-plane such that two of its sides are lying on the axis. If an electric field $E=E_{0}x\hat{k}$ is applied on the square. The flux passing through the square is 

 The figure shows the electric lines of force emerging from a charged body. If the electric fields at $\mathrm{A}$ and $\mathrm{B}$ are ${\mathrm{E}}_{\mathrm{A}}$ and ${\mathrm{E}}_{\mathrm{B}}$ respectively and if the distance between $\mathrm{A}$ and $\mathrm{B}$ is $\mathrm{r}$, then

Figure $\left(\mathrm{i}\right)$ shows an imaginary cube of edge length $L$. A uniformly charged rod of length $2L$ moves towards left at a small and constant speed $v$. At $t=0,$ the left end of the rod just touches the centre of the face of the cube opposite to it. Which of the graphs shown in fig. (ii) represents the flux of the electric field through the cube as the rod goes through it?

Eight point charges (can be assumed as uniformly charged small spheres and their centres at the corner of the cube) having value $q$ each are fixed at vertices of a cube. The electric flux through the square surface $ABCD$ of the cube is