$64$ small drops of water having same charge and same radius are combined to form one big drop. The ratio of capacitance of the big drop to the small drop is . . . . . . .

$A$ spherical capacitor has an outer sphere of radius $5 \text{ cm}$ and an inner sphere of radius $2 \text{ cm}$. When the inner sphere is earthed,its capacity is $C_1$,and when the outer sphere is earthed,its capacity is $C_2$. Then $\frac{C_1}{C_2}$ is

The radii of a spherical capacitor are $0.5 \ m$ and $0.6 \ m$. If the space between them is filled with a dielectric medium of dielectric constant $6$,what will be the capacitance of the capacitor?

$A$ spherical capacitor is made of two spherical shells of radii $a$ and $b$ $(b > a)$. The medium between the shells is air. What is the difference between the capacitances when the outer shell is grounded and when the inner shell is grounded?

If the circumference of a sphere is $2 \ m$,find the capacitance of the sphere in water in $pF$. (Take dielectric constant of water $K = 80$)

The potentials of the two plates of a capacitor are $+10\,V$ and $-10\,V$. The charge on one of the plates is $40\,C$. The capacitance of the capacitor is........$F$.