Physics MCQs

Notes:
Albert Einstein and Otto Stern proposed the concept of Zeropoint energy. It is the lowest possible energy that a quantum mechanical physical system may have.

Notes:
The speed of sound in a medium is determined by the properties of that medium, primarily its density and elasticity. The speed of sound is fastest in solids, followed by liquids, and then gases. Let’s analyze the given options:

[A] Air at zero degrees Celsius: The speed of sound in air increases with temperature. At lower temperatures, the molecules in the air have less kinetic energy, which results in a slower speed of sound. So, the speed of sound in air at 0°C is slower compared to higher temperatures.

[B] Air at 100 degrees Celsius: As mentioned earlier, the speed of sound in air increases with temperature. So, the speed of sound in air at 100°C would be faster than at 0°C but still slower than in a solid or liquid.

[C] Water: The speed of sound in water is significantly faster than in air. Water is denser and more elastic than air, which allows sound waves to travel through it more quickly.

[D] same in all: This statement is not correct. The speed of sound varies depending on the medium. It is not constant and is definitely not maximum everywhere.

So, among the given options, the maximum speed of sound would be in “Water” (Option C).

Notes:
Inertia is the resistance experienced by an object to any change in its velocity. This includes changes to the object’s speed, or direction of motion. Inertia of rest, Inertia of motion are the examples.

Notes:
The SI unit for dynamic viscosity η is the Pascal-second (Pa-s). It corresponds to the force (N) per unit area (m2) divided by the rate of shear (s-1).

Notes:
How the brain interprets the frequency of an emitted sound is called the pitch. Researchers have discovered a discrete region of the monkey brain that processes pitch, the relative high and low points of sound, by recognizing a single musical note played by different instruments.

Notes:
The phenomenon of light rays bending around the corners of obstacles is called diffraction. Diffraction refers to various phenomena that occur when a wave encounters an obstacle or a slit.

Notes:
Large Underground Xenon experiment (LUX) is located 1,510 m underground at the Sanford Underground Laboratory in Lead city, South Dakota, United States.

Notes:
Gravitational Forces are the weakest forces in nature. They obey inverse square law as they vary inversely as the square of the distance between the two bodies. They are central forces and conservative forces. They operate over very long distances having an infinite range.

Notes:
J.J Thompson was the first scientist to discover and identify the electrons and to make the discovery of the first subatomic particle. He was also the first scientist to find evidence for isotopes of a stable (non-radioactive) element in 1913, as part of his exploration into the composition of canal rays (positive ions). His experiments to determine the nature of positively charged particles led to the development of the mass spectrograph. J.J Thompson belonged to United Kingdom. He won the Nobel Prize in Physics in 1906 for his work on the conduction of electricity in gases.

Notes:
Astronomical Unit, Light year and Par sec are the units used to measure very large distances whereas slug is a unit to measure heavy masses. 1 slug = 14.57 kg