Question

Define dielectric constant of a medium. What is its $S.I$. unit?

Answer 1

The Dielectric constant (K) of the medium is the ratio of the permittivity of the substance (\varepsilon) to permittivity of the free space $\left({\epsilon }_0\right).$

i.e $K=\epsilon /{\epsilon }_0$

As Permittivity of medium and permittivity of free space both have same units(F/m ie Farad/meter) dielectric constant becomes dimensionless quantity.