Two charged spherical conductors of radius R₁ and R₂ are connected by a wire. Then the ratio of surface charge densities of the spheres ($$\sigma$$₁ / $$\sigma$$₂) is :

Column - I gives certain physical terms associated with flow of current through a metallic conductor. Column-II gives some mathematical relations involving electrical quantities. Match column-I and column-II with appropriate relations.

	Column - I		Column - II
(A)	Drift Velocity	(P)	$${m \over {n{e^2}p}}$$
(B)	Electrical Resistivity	(Q)	$$ne{\upsilon _d}$$
(C)	Relaxation Period	(R)	$${{eE} \over m}\tau $$
(D)	Current Density	(S)	$${E \over J}$$

Twenty seven drops of same size are charged at 220V each. They combine to form a bigger drop. Calculate the potential of the bigger drop.

A short electric dipole has a dipole moment of 16 $$ \times $$ 10^-9 Cm. The electric potential due to the dipole at a point at a distance of 0.6 m from the centre of the dipole, situated on a line making an angle of $$60^\circ $$ with the dipole axis is :

$$\left( {{1 \over {4\pi {\varepsilon _0}}} = 9 \times {{10}^9}N{m^2}/{C^2}} \right)$$