MCQ Detailed View

Viscosity is a measure of a fluid's resistance to flow. It depends on the internal friction between molecules in a liquid or gas. The greater the viscosity, the slower a fluid flows under an applied force. Measuring viscosity is essential in physical chemistry, fluid dynamics, and various industrial processes.

The instrument used to measure viscosity is called a viscometer. There are several types of viscometers, including capillary viscometers, rotational viscometers, falling sphere viscometers, and oscillating viscometers. Each type measures the resistance of a fluid under specific conditions to calculate its viscosity, typically expressed in units like poise (P), centipoise (cP), or Pascal-seconds (Pa·s).

Capillary viscometers, such as the Ostwald viscometer, measure the time it takes for a fluid to flow between two points through a narrow tube. Rotational viscometers measure the torque required to rotate a spindle in the fluid. Falling ball or sphere viscometers measure how fast a sphere falls through the liquid under gravity.

The other options listed are used for different measurements. A hygrometer measures humidity in the air. A hydrometer measures the specific gravity or density of liquids. An anemometer measures wind speed. None of these are related to the measurement of viscosity.

Understanding viscosity is important for analyzing the behavior of lubricants, paints, pharmaceuticals, and even biological fluids. In chemistry and engineering, viscosity measurements help determine flow rates, diffusion, and efficiency of fluid systems.

Viscometers are widely used in chemical laboratories and industries to ensure the quality and consistency of liquid products. They are also important in research involving temperature-dependent fluid behavior, since viscosity generally decreases with increasing temperature.