Physics - Study Mode
[#1271] A metal plate with a circular hole at the centre is heated. What will happen to the area of the hole ?
Correct Answer
(A) Increase
Explanation
Solution: Assuming the disc is uniform and isotropic (the same in different directions), the hole will expand in the same ratio as the metal. It is because the thermal expansion equation applies to all lengths associated with the metal, including the circumference of the hole, since the edge of the hole is made out of metal. And if the circumference of the hole expands, so does the diameter.
[#1272] Air is said to be saturated when
Correct Answer
(B) It contains the maximum content of water vapour
Explanation
Solution: Air is said to be saturated when the amount of water vapour in the air is the maximum possible at an existing temperature and pressure. Air is said to be saturated at 100 percent relative humidity when it contains the maximum amount of moisture possible at that specific temperature.
[#1273] At constant pressure, the volume of a fixed mass of a gas is directly proportional to its absolute temperature. It is the statement of
Correct Answer
(B) Charle's Law
Explanation
Solution: Charles's law, or the law of volumes, was found in 1787 by Jacques Charles. It states that, for a given mass of an ideal gas at constant pressure, the volume is directly proportional to its absolute temperature, assuming in a closed system.
[#1274] A mirage occurs because of
Correct Answer
(B) Total internal reflection by layers of air
Explanation
Solution: A mirage occurs because of total internal reflection by layers of air.
[#1275] Optical fibres are based on the phenomenon of
Correct Answer
(D) Total Internal Reflection
Explanation
Solution: Optical fibers operate based on the principle of total internal reflection phenomenon that occurs at the interface between the core and the cladding provided that the angle of the incident light inside the core is higher than the angle called critical angle.