GK - Physics

36.

The flow of thermal energy is called

Answer

Answer :

Option A

Explanation :


The flow of thermal energy due to differences in their temperatures is called Heat.
37.

The phenomenon of change in direction of light when it passes from one medium to another is called

Answer

Answer :

Option C

Explanation :


Refraction is the change in direction of wave propagation due to a change in its transmission medium.Due to the change of medium, the phase velocity of the wave is changed but its frequency remains constant. Refraction of light is the most commonly observed refractive phenomenon, but any type of wave can refract when it interacts with a medium.
38.

Mercury is commonly used as a thermometric fluid rather than water because

Answer

Answer :

Option C

Explanation :


Mercury is commonly used as a thermometric fluid rather than water because mercury has greater visibility than water. Mercury has high melting and boiling points making it a liquid over a broad range of temperature. Mercury doesn't stick to the surface of the thermometer but water does.
39.

When a piece of stone is immersed in water, it displaces water of equal

Answer

Answer :

Option C

Explanation :


Archimedes Principle states that upward buoyant force exerted on a body immersed in a fluid is equal to the weight of the fluid the body displaces.
40.

A nuclear reactor is said to have become 'critical' when

Answer

Answer :

Option D

Explanation :


Criticality means that a reactor is controlling a sustained fission chain reaction, where each fission event releases a sufficient number of neutrons to maintain an ongoing series of reactions.
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