Electrostatic field of a long uniformly charged wire varies with distance $(r)$ according to relation

A thin spherical conducting shell of radius $R$ has a charge $q.$ Another charge $Q$ is placed at the centre of the shell. The electrostatic potential at a point $p$ a distance $R/2$ from the centre of the shell is

For shown situation of two dipoles the nature of forces between them are

When a proton is accelerated through $1\,V,$ then its kinetic energy will be........$eV$

A parallel plate capacitor of area $A$, plate separation $d$ and capacitance $C$ is filled with three different dielectric materials having dielectric constant $K_1,K_2$ and $K_3$ as shown. If a single dielectric material is to be used to have the same capacitance $C$ in this capacitor, then its dielectric constant $K$ is given by: ($A =$ Area of plates)

Consider a cube of uniform charge density $\rho$. The ratio of electrostatic potential at the centre of the cube to that at one of the corners of the cube is