If $27$ identical charged conducting spheres each of capacitance $10 \mu F$ combine to form a big sphere,then the capacitance of the big sphere is: (in $\mu F$)

What is a capacitor? Explain capacitance and give its $SI$ unit.

The dimension of capacitance is:

$A$ cylindrical capacitor has two cylinders of radii $1.4\,cm$ and $1.5\,cm$ and length $15\,cm$. The outer cylinder is earthed and the inner cylinder is given a charge of $3.5\,\mu C$. Determine the capacitance of the system and the potential of the inner cylinder.

The respective radii of the two spheres of a spherical condenser are $12 \; cm$ and $9 \; cm$. The dielectric constant of the medium between them is $6$. The capacity of the condenser will be

$A$ cylindrical capacitor has inner and outer conductors whose radii are in the ratio $10:1$. The inner conductor is replaced by a wire whose radius is half of the original inner conductor. To obtain the same capacitance as the original capacitor,by what ratio should the length of the wire be increased?