Three equal charges '$$\mathrm{q}_1$$', '$$^{\prime} \mathrm{q}_2$$' and '$$\mathrm{q}_3$$' are placed on the three corners of a square of side 'a'. If the force between $$\mathrm{q}_1$$ and $$\mathrm{q}_2$$ is '$$\mathrm{F}_{12}$$' and that between $$\mathrm{q}_1$$ and $$\mathrm{q}_3$$ is '$$\mathrm{F}_{13}$$', then the ratio of magnitudes $$\left(\frac{F_{12}}{F_{13}}\right)$$ is

Two spherical conductors of radii $$4 \mathrm{~cm}$$ and $$5 \mathrm{~cm}$$ are charged to the same potential. If '$$\sigma_1$$' and '$$\sigma_2$$' be the respective values of the surface density of charge on the two conductors then the ratio $$\sigma_1: \sigma_2$$ is

An electron of mass '$$m$$' and charge '$$q$$' is accelerated from rest in a uniform electric field of strength '$$E$$'. The velocity acquired by the electron when it travels a distance '$$L$$' is

Two particles $$A$$ and $$B$$ having same mass have charge $$+q$$ and $$+4 q$$ respectively. When they are allowed to fall from rest through same electric potential difference, the ratio of their speeds '$$V_A$$' to '$$\mathrm{V}_{\mathrm{B}}$$' will become