Three identical capacitors $$𝐶_{1}, 𝐶_{2}$$ and $$𝐶_{3}$$ have a capacitance of 1.0 $$\mu$$𝐹 each and they are uncharged initially. They are connected in a circuit as shown in the figure and $$𝐶_{1}$$ is then filled completely with a dielectric material of relative permittivity $$\epsilon_{r}$$.The cell electromotive force (emf) $$𝑉_{0}$$ = 8 𝑉. First the switch $$𝑆_{1}$$ is closed while the switch $$𝑆_{2}$$ is kept open. When the capacitor $$𝐶_{3}$$ is fully charged, $$𝑆_{1}$$ is opened and $$𝑆_{2}$$ is closed simultaneously. When all the capacitors reach equilibrium, the charge on $$𝐶_{3}$$ is found to be 5 $$\mu$$𝐶. The value of $$\epsilon_{r}$$ =____________.