In Millikan’s oil drop experiment, what is the terminal speed of an uncharged drop of radius 2.0 x ${{10}^{-5}}$ m and density of 1.2 X ${{10}^{3}}$ kg ${{m}^{-3}}$? Take the viscosity of air at the temperature of the experiment to be 1.8 x ${{10}^{-5}}$ Fas. How much is the viscous force on the drop at that speed ? Neglect buoyancy of the drop due to air.
