Three dipoles each of dipole moment of magnitude p are placed tangentially on a circle of radius $R$ in its plane positioned at equal angle from each other as shown in the figure. Then the magnitude of electric field intensity at the centre of the circle will be

 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?