Two identical parallel plate air capacitors are connected in series to a battery of emf '$$\mathrm{V}$$'. If one of the capacitor is inserted in liquid of dielectric constant '$$\mathrm{K}$$' then, potential difference of the other capacitor will become

A condenser of capacity '$$\mathrm{C}_1$$' is charged to potential '$$\mathrm{V}_1$$' and then disconnected. Uncharged capacitor of capacity '$$\mathrm{C}_2$$' is connected in parallel with '$$\mathrm{C}_1$$'. The resultant potential '$$\mathrm{V}_2$$' is

The resultant capacity between points A and B in the given circuit is

An air filled parallel plate capacitor has a capacity $$2 \mathrm{~pF}$$. The sepeartion of the plates is doubled and the interspace between the plates is filled with dielectric material, then the capacity is increased to $$6 ~\mathrm{pF}$$. The dielectric constant of the material is