After charging a capacitor the battery is removed. Now by placing a dielectric slab between the plates

A parallel plate capacitor is filled with two dielectrics as shown in figure. If $A$ is area of each plate, then the effective capacitance between $X$ and $Y$ is

An insulator plate is passed between the plates of a capacitor. Then current

In the adjoining diagram, two geometrically identical capacitors $A$ and $B$ are connected to a battery. Air is filled between the plates of $C_1$ and a dielectric is filled between the plates of $C_2,$ then