Six charges of magnitude $+q$ and $–q$ are fixed at the corners of a regular hexagon of edge length $a$ as shown in the figure. The electrostatic potential energy of the system of charged particles is

The variation of potential with distance $r$ from a fixed point is shown in the figure. The electric field at $r=5 \mathrm{cm}$, is

The variation of potential with distance $r$ from a fixed point is shown in the figure.

The electric force acting on a point charge of $2 \mathrm{C}$ placed at the origin will be

The electric potential $V$ as a function of distance $x$ (in $\mathrm{metre}$) is given by $V=\left(5x^2+10x–9\right) \mathrm{volt}$. The value of the electric field at $x=1 \mathrm{m}$ would be