The dielectric constant of pure water is $81$. Its permittivity will be:

The dielectric constant of a metal is ........ .

When a dielectric is placed in an external electric field,the electric field inside the dielectric is

$Assertion \; (A)$: 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:

What happens if the magnitude of the capacitance of a capacitor is large? Define dielectric breakdown and dielectric strength.

Explain the polarization of a nonpolar molecule in a uniform electric field and define linear isotropic dielectrics.