Practice MCQ Questions and answers on Physics-GK

1

The oil in the wick of lamp rises due to

A) Pressure difference B) Pheonomenon of capillarity C) Low viscosity of oil D) Force of cohesion

Discuss

Answer & Solution

Answer: Option B

Solution:

The oil in the wick of an oil lamp rises up due to capillary action. This effect is due to surface tension of liquids. The wick here acts as a capillary tube

2

Which of the following devices can be used to detect radiant heat ?

A) Liquid thermometer B) Six's maximum and minimum thermometer C) Constant volume air thermometer D) Thermopile

Discuss

Answer & Solution

Answer: Option D

Solution:

Based on the thermoelectric effect, the thermopile can be used as a heat sensor to measure thermal radiation. A thermopile is made of thermocouple junction pairs connected electrically in series. Thermocouples near the ground measures radiant energy.

3

Shock-absorbers are usually made of steel as it :

A) Is not brittle B) Has lower elasticity C) Has higher elasticity D) Has no ductile property

Discuss

Answer & Solution

Answer: Option C

Solution:

A shock absorber is a mechanical device designed to smooth out or damp shock impulse, and dissipate kinetic energy. Steel is an alloy made by combining iron and other elements, the most common of these being carbon. When carbon is used, its content in the steel is between 0.2% and 2.1% by weight, depending on the grade. Varying the amount of alloying elements and the form of their presence in the steel (solute elements, precipitated phase) controls qualities such as the higher elasticity, hardness, ductility, and tensile strength of the resulting steel.

4

The dimensional formula ML^–1T^–2 corresponds to

A) Modulus of elasticity B) Viscosity C) Moment of a force D) Thrust

Discuss

Answer & Solution

Answer: Option A

Solution:

The dimensional formula ML^-1T^-2 corresponds to modulus of elasticity.

5

Amount of water vapour (gaseous) in a given volume of air (cubic metre) is known as:

A) Mixing ratio B) Relative humidity C) Absolute humidity D) Specific humidity

Discuss

Answer & Solution

Answer: Option C

Solution:

The relative humidity of air at a given temperature is the ratio of mass of water vapour actually present in a certain volume of air to the mass of water vapour required to saturate the same volume of air at the same temperature, miltiplied by 100. Absolute Humidity refers to the amount of water vapour present in unit volume of air, expressed in grams per cubic metre.

6

An ideal gas cannot be

A) Liquified B) Solidified C) Both A & B D) None of the above

Discuss

Answer & Solution

Answer: Option A

Solution:

An ideal gas have no intermolecular force of attraction, so it cannot be liquefied by applying high pressure and decreasing temperature.

7

Super cooling stands for cooling of a liquid :

A) At freezing point B) Below freezing point C) At melting point D) Above melting point

Discuss

Answer & Solution

Answer: Option B

Solution:

Supercooling, also known as undercooling, is the process of lowering the temperature of a liquid or a gas below its freezing point without it becoming a solid.

8

The spring constant of a spring depends on its

A) Length only B) Material only C) Length and its diameter D) Thickness, its diameter and its material

Discuss

Answer & Solution

Answer: Option D

Solution:

In dealing with a coil spring the spring constant will depend on the stiffness of the spring material, the thickness of the wire from which the spring is wound and, diameter of the turns of the coil, the number of turns per unit length and the overall length of the spring.

9

The average kinetic energy of the molecules of an ideal gas is directly proportional to

A) Velocity of Molecules B) Mass of Molecules C) Absolute temperature of the gas D) Temperature of environment

Discuss

Answer & Solution

Answer: Option C

Solution:

The average kinetic energy of gas molecules is directly proportional to absolute temperature only; this implies that all molecular motion ceases if the temperature is reduced to absolute zero.

10

Steel is more elastic than rubber because it :

A) Requires larger deforming force B) Is never deformed C) Is deformed very easily D) Is harder than rubber

Discuss

Answer & Solution

Answer: Option A

Solution:

The elasticity of a material is determined by its ability to return to its original shape after being deformed. Steel, being a metal, has a high modulus of elasticity and requires a larger deforming force to change its shape, but it also has the ability to return to its original shape once the force is removed. Rubber, on the other hand, is a polymer with a lower modulus of elasticity, meaning it is easily deformed and doesn't return to its original shape as effectively as steel.