Explain briefly the term viscosity. Define coefficient of viscosity. What are its units?
Viscosity. The viscosity of the liquid is its property by virtue of which it tends to oppose the relative motion between two adjacent layers. In other words, all liquids exhibit resistance to flow. It is clear that the resistance to flow is governed by intermolecular forces. If the intermolecular forces are strong, there is greater resistance to flow i.e. viscosity has a high value. For example, glycerol, honey and concentrated H2SO4 are highly viscous due to stronger intermolecular attractive forces.
The coefficient of viscosity: It has been found that the force of friction (F) per unit area is directly proportional to the difference in velocity v of the two adjacent layers and inversely proportional to the distance x, between them
The coefficient of viscosity may be defined as the force in newton per square metre required to maintain a difference of velocity of one metre per second, between two parallel layers of the liquid at a distance of one metre from each other. Unit. It is measured in kg m–1 s–1.
