Answer: C. Between 0.002mm to 0.2mm
Stokes's law is valid for particle size between 0.002mm to 0.2mm.
Stokes law states that the force resisting a spherical body is a viscous fluid is directly proportional to the velocity of the sphere, the radius of the sphere and the viscosity of the fluid.
Settling Velocity by stokes law is given by:
V = gd2(ps-pw)/18μ
V = Velocity of settling particle
D = Diameter of settling particle
g = Acceleration due to gravity
ps = Density of settling particle
pw = Density of water
μ = Dynamic viscosity of fluid
Stokes law is valid for particle size between 0.002mm to 0.2mm and upto a maximum Reynold’s number of 1.
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