Two parallel plate capacitors X and Y have the same area of plates and same separation between them.
X has air between the plates while Y contains a dielectric medium of `e_(r ) = 4`

(i) Calculate capacitance of each capacitor if equivalent capacitance of the combination is `4mu_(F)`
(ii) Calculate the potential difference between the plates of X and Y
(iii) Estimate the ratio of electrostatic energy stored in X and Y .