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All questions of Viscosity for UPSC CSE Exam

Viscosity is an important property in which field?
  • a)
    Medicine
  • b)
    Engineering
  • c)
    Biology
  • d)
    Astronomy
Correct answer is option 'B'. Can you explain this answer?

Viscosity is an important property in engineering, where it is crucial to understand and control the flow characteristics of fluids in various applications.

Which type of fluid has a higher viscosity?
  • a)
    Honey
  • b)
    Water
  • c)
    Molasses
  • d)
    Motor oil
Correct answer is option 'A'. Can you explain this answer?

Honey has a higher viscosity compared to water, making it flow more slowly due to its greater resistance to flow.

Which parameter determines the resistance to flow in a fluid?
  • a)
    Volumetric flow rate
  • b)
    Velocity
  • c)
    Viscosity
  • d)
    Pressure
Correct answer is option 'C'. Can you explain this answer?

Viscosity is the parameter that determines the resistance to flow in a fluid. It depends on the internal friction and cohesive forces within the fluid.

Which mathematical equation represents Newton's Law of Viscosity?
  • a)
    F = ma
  • b)
    E = mc²
  • c)
    F = μA(dv/dy)
  • d)
    P = ρgh
Correct answer is option 'C'. Can you explain this answer?

Newton's Law of Viscosity is mathematically represented by the equation F = μA(dv/dy), where F is the viscous force, μ is the dynamic viscosity, A is the area, and (dv/dy) is the velocity gradient along the direction of flow.

What is the SI unit of viscosity?
  • a)
    Newton
  • b)
    Pascal
  • c)
    Ohm
  • d)
    Poise
Correct answer is option 'D'. Can you explain this answer?

The SI unit of viscosity is the poise (Pa·s), named after the French physician Jean Louis Marie Poiseuille.

The viscosity of a liquid decreases with:
  • a)
    Decreasing temperature
  • b)
    Increasing temperature
  • c)
    Decreasing pressure
  • d)
    Increasing pressure
Correct answer is option 'B'. Can you explain this answer?

The viscosity of a liquid decreases with increasing temperature, as higher temperatures reduce intermolecular forces and increase the fluid's kinetic energy.

Which of the following factors affects the viscosity of a fluid?
  • a)
    Temperature
  • b)
    Density
  • c)
    Pressure
  • d)
    All of the above
Correct answer is option 'D'. Can you explain this answer?

Factors affecting viscosity include temperature, density, and pressure. Higher temperatures decrease viscosity, whereas higher density and pressure increase viscosity.

What is viscosity?
  • a)
    The ability of a substance to flow
  • b)
    The force acting on an object submerged in a fluid
  • c)
    The resistance of a fluid to flow
  • d)
    The measure of the gravitational force on an object
Correct answer is option 'C'. Can you explain this answer?

Viscosity is the measure of a fluid's resistance to flow. It represents the internal friction between layers of a fluid as they move past each other. Higher viscosity means the fluid flows more slowly, while lower viscosity indicates easier flow.

Which fluid has the highest viscosity at room temperature?
  • a)
    Olive oil
  • b)
    Water
  • c)
    Alcohol
  • d)
    Mercury
Correct answer is option 'D'. Can you explain this answer?

Mercury has the highest viscosity at room temperature among the given options. Its thick consistency contributes to its high resistance to flow.

Which law states that the viscosity of most liquids decreases with increasing temperature?
  • a)
    Hooke's Law
  • b)
    Ohm's Law
  • c)
    Pascal's Law
  • d)
    Newton's Law of Cooling
Correct answer is option 'D'. Can you explain this answer?

Newton's Law of Cooling states that the viscosity of most liquidsdecreases with increasing temperature. As the temperature rises, the intermolecular forces weaken, allowing the liquid molecules to move more freely and reducing the resistance to flow.

The viscosity of a gas increases with:
  • a)
    Increasing pressure
  • b)
    Decreasing pressure
  • c)
    Decreasing temperature
  • d)
    Increasing temperature
Correct answer is option 'C'. Can you explain this answer?

The viscosity of a gas increases with decreasing temperature, as lower temperatures reduce the kinetic energy of gas molecules, causing them to move more slowly.

Which instrument is commonly used to measure the viscosity of a fluid?
  • a)
    Hydrometer
  • b)
    Tonometer
  • c)
    Rheometer
  • d)
    Spectrometer
Correct answer is option 'C'. Can you explain this answer?

A rheometer is commonly used to measure the viscosity of a fluid. It applies shear stress to the fluid and measures the resulting deformation to determine its viscosity.

Which phenomenon explains why honey flows slowly compared to water?
  • a)
    Viscous flow
  • b)
    Surface tension
  • c)
    Capillary action
  • d)
    Turbulent flow
Correct answer is option 'A'. Can you explain this answer?

Honey flows slowly compared to water due to its high viscosity. Viscous flow refers to the slow movement of a fluid, characterized by the fluid's resistance to flow and internal friction.

The concept of viscosity was first introduced by:
  • a)
    Sir Isaac Newton
  • b)
    Albert Einstein
  • c)
    Archimedes
  • d)
    Galileo Galilei
Correct answer is option 'A'. Can you explain this answer?

The concept of viscosity was first introduced by Sir Isaac Newton, who formulated the laws of motion and studied the behavior of fluids.

Which law describes the relationship between viscosity and temperature for gases?
  • a)
    Boyle's Law
  • b)
    Newton's Law of Viscosity
  • c)
    Gay-Lussac's Law
  • d)
    Charles Law
Correct answer is option 'B'. Can you explain this answer?

- Newton's Law of Viscosity is the correct answer.
- For gases, as temperature increases, viscosity generally increases because higher temperatures cause gas molecules to move faster and collide more frequently.
- This differs from liquids, where increasing temperature typically decreases viscosity.
- Newton's law provides a fundamental understanding of how fluid viscosity changes with temperature, particularly in gases.

Which of the following fluids has the highest viscosity?
  • a)
    Air
  • b)
    Water
  • c)
    Glycerin
  • d)
    Ethanol
Correct answer is option 'C'. Can you explain this answer?

Glycerin has the highest viscosity among the given options, making it thicker and more resistant to flow compared to air, water, or ethanol.

Which of the following substances has the highest viscosity?
  • a)
    Water
  • b)
    Gasoline
  • c)
    Air
  • d)
    Honey
Correct answer is option 'D'. Can you explain this answer?

Honey has the highest viscosity among the given options, as it is thicker and flows much more slowly compared to the other substances.

Chapter doubts & questions for Viscosity - Lucent for GK 2025 is part of UPSC CSE exam preparation. The chapters have been prepared according to the UPSC CSE exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for UPSC CSE 2025 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.

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