Practice MCQ Questions and answers on Physics-GK

If the relative humidity is 100 percent, water will not evaporate as the air is already saturated with moisture. When relative humidity approaches 100 percent, condensation can occur. The lower the relative humidity, the easier it is for moisture to evaporate.

Relative humidity is expressed as percentage.

According to special theory of relativity the mass of a particle increases with increase in velocity with respect to an observer.

A bolometer is a device for measuring the power of incident electromagnetic radiation via the heating of a material with a temperature-dependent electrical resistance. It was invented in 1878 by the American astronomer Samuel Pierpont Langley. A bolometer consists of an absorptive element, such as a thin layer of metal, connected to a thermal reservoir (a body of constant temperature) through a thermal link. The result is that any radiation impinging on the absorptive element raises its temperature above that of the reservoir — the greater the absorbed power, the higher the temperature.

Boyle's law relates to Kinetic Theory of Gases.

Charles law states that the volume of an ideal gas is directly proportional to the absolute temperature at constant pressure. The law also states that the Kelvin temperature and the volume will be in direct proportion when the pressure exerted on a sample of a dry gas is held constant.

The ''Greenhouse effect' is mainly due to increase in atmospheric carbon dioxide.

Thermohaline circulation is mainly due to cold, dense ocean water sinking and warmer water replacing it.

A hygrometer is an instrument used to measure relative humidity. Humidity is the measure of the amount of moisture in the air. A psychrometer is an example of a hygrometer.

Low temperature and high pressure set of conditions represents the easiest way to liquefy a gas. Liquefaction of gases is physical conversion of a gas into a liquid state (condensation). The processes are used for scientific, industrial and commercial purposes. Many gases can be put into a liquid state at normal atmospheric pressure by simple cooling; a few, such as carbon dioxide, require pressurization as well. Liquefaction is used for analyzing the fundamental properties of gas molecules (intermolecular forces), for storage of gases. The liquefaction of gases is a complicated process that uses various compressions and expansions to achieve high pressures and very low temperatures, using, for example, turbo-expanders.