If the dielectric constant and dielectric strength are denoted by $k$ and $x$ respectively,then a material suitable for use as a dielectric in a capacitor must have

If the dielectric constant of a substance $K = \frac{4}{3}$,then the electric susceptibility $\chi$ in terms of vacuum permittivity $\varepsilon_0$ is

Why can a metal not be used as a dielectric in a capacitor?

Explain the difference in the behaviour of a conductor and a dielectric in the presence of an external electric field.

Polar molecules are the molecules:

$Assertion \; (A)$: Non-polar materials do not have any permanent dipole moment.
$Reason \; (R)$: When a non-polar material is placed in an electric field,the centre of the positive charge distribution of its individual atom or molecule coincides with the centre of the negative charge distribution.
In the light of the above statements,choose the most appropriate answer from the options given below: