Four condensers are joined as shown in the adjoining figure. The capacity of each is $8 \mathrm{\mu F}$. The equivalent capacity between the points $A$ and $B$ will be

  

 

The capacitance of a parallel capacitor is $C$. If it is half filled with a dielectric of constant $K$, then, the new capacitance will become

Find equivalent capacitance between $X$ and $Y$ if each capacitor is $4 \mathrm{\mu F}$.

In the given circuit, if point $C$ is connected to the earth and a potential of $+2000 \mathrm{V}$ is given to the point $A,$ the potential at $B$ is