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

A point charge $$\mathrm{Q}$$ is placed at the centre of the line joining two equal point charges $$+\mathrm{q}$$ and $$+\mathrm{q}$$. The value of $$Q$$ if the system of the charges is in equilibrium, is

When a piece of polythene is rubbed with wool, a negative charge of $$4 \times 10^{-7} \mathrm{C}$$ is developed on the polythene. The number of electrons transferred from wool to polythene is $$[e=1.6 \times\left.10^{-19} \mathrm{C}\right]$$