Write the capacitance of a parallel plate capacitor with a medium of dielectric constant $K$.

(N/A) The capacitance of a parallel plate capacitor with vacuum or air between its plates is given by $C_0 = \frac{\epsilon_0 A}{d}$,where $\epsilon_0$ is the permittivity of free space,$A$ is the area of the plates,and $d$ is the distance between them.
When a dielectric medium of dielectric constant $K$ is introduced between the plates,the permittivity of the medium becomes $\epsilon = K \epsilon_0$.
Therefore,the new capacitance $C$ is given by $C = \frac{\epsilon A}{d} = \frac{K \epsilon_0 A}{d}$.
Substituting the expression for $C_0$,we get $C = K C_0$.