Which of the following laws is used in Millikan's oil drop experiment for the determination of the charge of an electron?

Two spheres of different material are falling through a liquid of density $\rho_L = 2 \times 10^3 \ kg/m^3$ with the same uniform terminal speed. The density of sphere $1$ is $\rho_1 = 8 \times 10^3 \ kg/m^3$ and the density of sphere $2$ is $\rho_2 = 11 \times 10^3 \ kg/m^3$. The ratio of their radii $(r_1/r_2)$ is:

$A$ small spherical ball of radius $r$,falling through a viscous medium of negligible density has terminal velocity $v$. Another ball of the same mass but of radius $2r$,falling through the same viscous medium will have terminal velocity:

The velocity of a small ball of mass $m$ and density $\rho$ when dropped in a container filled with glycerine of density $\sigma$ becomes constant after some time. The viscous force acting on the ball in the final stage is

$A$ lead shot of $1 \, mm$ diameter falls through a long column of glycerine. The variation of its velocity $v$ with distance covered is represented by:

$A$ viscous fluid is flowing through a cylindrical tube. The velocity distribution of the fluid is best represented by the diagram