Capacitor

A parallel plate capacitor with air between the plates has a capacitance of \(15 \mathrm{~pF}\). the separation between the plates is \(d\). The space between the plates is now filled with two dielectrics constant \(k_1=3\) and thickness \(d / 3\) while the other one has dielectric constant \(k_2=6\) and thickness \(2 d / 3\). Capacitance of the capacitor is now