Physics - Fluid Question with Solution | TestHub

In Millikan's oil drop experiment, what is viscous force acting on an uncharged drop of radius$2.0\times {10}^{-5} \mathrm{m}$and density$1.2\times {10}^3 \mathrm{kg} {\mathrm{m}}^{-3}$? Take viscosity of liquid$=1.8\times {10}^{-5} \mathrm{N} \mathrm{s} {\mathrm{m}}^{-2}.$(Neglect buoyancy due to air).