In Millikan's oil drop experiment , what is the terminal speed of an uncharged drop of radius 2.0xx10^(-5)mand density 1.2xx10^(3)kgm^(-3) . Take the viscosity of air at the temperature of the experiment to be 1.8xx10^(-5) Pa.s . Howmuch is the viscous force on the drop at thatspeed ?Neglect buoyancy of the drop due to air .

In Millikan's oil drop experiment , what is the terminal speed of an u

1.	In Millikan's oil drop experiment , what is the terminal speed of an uncharged drop of radius 2.0xx10^(-5)mand density 1.2xx10^(3)kgm^(-3) . Take the viscosity of air at the temperature of the experiment to be 1.8xx10^(-5) Pa.s . Howmuch is the viscous force on the drop at thatspeed ?Neglect buoyancy of the drop due to air .
Answer» Solution :Here radius of DROP `r=2.0xx10^(-5)m` Density of oil`rho=1.2xx10^(3)kgm^(-3)` Density of air (dropis of air ) `rho_(o)=0` The COEFFICIENT of viscosity of oil, `ETA=1.8xx10^(-5)` Pas Terminal velocityfrom Stock.s law , `v_(t)=(2)/(9)(r^(2)g)/(eta)(rho-rho_(o))` `=(2r^(2)gQ)/(9eta)` `=(2xx4xx10^(-10)xx9.8xx1.2xx10^(3))/(9xx1.8xx10^(-5))` `=5.807xx10^(-2)` `v_(t)=5.8cms^(-1)` Viscous force on drop from Stoke.s law `F_(v)=6pietarv_(t)` `=6xx3.14xx1.8xx10^(-5)xx2xx10^(-5)xx5.8xx10^(-2)` `=393.34xx10^(-12)` `=3.93xx10^(-10)N`