Figure shows variation of Coulomb force $(F)$ acting between two point charges with $\frac{1}{r^2}, r$ being the separation between the two charges $\left(q_1, q_2\right)$ and $\left(q_2\right. q_3$ ). If $q_2$ is positive and least in magnitude, then the magnitudes of $q_1, q_2$ and $q_3$ are such that

Assertion (A): Equal amount of positive and negative charges are distributed uniformly on two halves of a thin circular ring as shown in figure. The resultant electric field at the centre O of the ring is along OC.

Reason (R): It is so because the net potential at $O$ is not zero.

The magnitude of the electric field due to a point charge object at a distance of $$4.0 \mathrm{~m}$$ is $$9 \frac{\mathrm{N}}{\mathrm{C}}$$. From the same charged object the electric field of magnitude, $$16 \frac{\mathrm{N}}{\mathrm{C}}$$ will be at a distance of

A point $$P$$ lies at a distance $$x$$ from the mid point of an electric dipole on its axis. The electric potential at point $$\mathrm{P}$$ is proportional to