Electrostatic force between two identical charges placed in vacuum at distance of $$r$$ is F. A slab of width $$\frac{r}{5}$$ and dielectric constant 9 is inserted between these two charges, then the force between the charges is

An electric dipole with dipole moment $$5 \times 10^{-7} \mathrm{C}-\mathrm{m}$$ is in the electric field of $$2 \times 10^4 \mathrm{NC}^{-1}$$ at an angle of $$60^{\circ}$$ with the direction of the electric field. The torque acting on the dipole is

Two positive point charges of $$10 \mu \mathrm{C}$$ and $$12 \mu \mathrm{C}$$ are placed 10 cm apart in air. The work done to bring them 6 cm closer is

What is the electric flux for Gaussian surface $$A$$ that encloses the charged particles in free space? [Given, $$q_1=-14 \mathrm{~nC}, q_2=78.85 \mathrm{~nC}, \left.q_3=-56 \mathrm{~nC}\right]$$