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Questions and Answers
Define the coefficient of viscosity.
Define the coefficient of viscosity.
The coefficient of viscosity is the force per unit area required to maintain unit velocity difference between two parallel layers unit distance apart.
What property of liquids determines how readily they flow?
What property of liquids determines how readily they flow?
Viscosity
What is the SI unit of the coefficient of viscosity?
What is the SI unit of the coefficient of viscosity?
kg m^{-1} s^{-1}
What is fluidity in terms of viscosity?
What is fluidity in terms of viscosity?
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What happens to the flow of liquid when the displacement of different layers becomes steady?
What happens to the flow of liquid when the displacement of different layers becomes steady?
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Express the force per unit area required to maintain steady flow mathematically.
Express the force per unit area required to maintain steady flow mathematically.
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What is the viscosity unit called in the CGS system?
What is the viscosity unit called in the CGS system?
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What is the relationship between the coefficient of viscosity, density, and time of flow?
What is the relationship between the coefficient of viscosity, density, and time of flow?
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What formula represents the viscosity of water (ηw) in terms of constants?
What formula represents the viscosity of water (ηw) in terms of constants?
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How is the coefficient of viscosity of a liquid (ηl) compared to water derived?
How is the coefficient of viscosity of a liquid (ηl) compared to water derived?
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Study Notes
Viscosity
- Viscosity is the property of liquids that determines their flow.
- It is compared in terms of the coefficient of viscosity.
Coefficient of Viscosity
- The coefficient of viscosity is the force per unit area required to maintain unit velocity difference between two parallel layers unit distance apart.
- It is denoted by η (eta) and its unit is g cm^-1 s^-1 or poise.
- Smaller units centipoise (10^-2 poise) and millipoise (10^-3 poise) are used.
- The SI unit is kg m^-1 s^-1.
Fluidity
- The reciprocal of the coefficient of viscosity is called fluidity.
Characteristics of Viscosity
- The coefficient of viscosity is proportional to the density of the liquid and the time of flow of the liquid.
- It is dependent on temperature.
Relationship Between Viscosity and Temperature
- The coefficient of viscosity of a liquid is proportional to the temperature and density of the liquid.
- η = Constant T d, where η is the coefficient of viscosity, T is the temperature, and d is the density of the liquid.
Comparison of Viscosity of Two Liquids
- The ratio of the coefficients of viscosity of two liquids is equal to the ratio of their temperatures and densities.
- η_l / η_w = T_1 / T × d_1 / d_w, where η_l and η_w are the coefficients of viscosity of the two liquids, and T_1, d_1, T, and d_w are their respective temperatures and densities.
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Description
Understand the concept of viscosity, the flow of liquids, and the coefficient of viscosity with molecular layers on a glass plate.