Physics MCQs

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The sunlight that reaches the earth has ultraviolet A and ultraviolet B (UVA and UVB) rays. These ultraviolet rays are the main causes of damage to the skin from the sun. UVA and UVB rays affect the skin’s sensitivity to sun exposure in different ways.

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Bats use SONAR (Sound Navigation & Ranging).Sonar is a technique that uses sound propagation to navigate, communicate with or detect objects on or under the surface of the water, such as other vessels.

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This question is related to Antoine equation. Water to get boil, its vapour pressure must reach to its surrounding pressure. In a pressure cooker, it boils at the highest temperature. Elevation of Kochi is 0 m, ooty is 2,486 m, Mount Abu is 1,200 m, New Delhi is 216 m, Shimla is 2,205 m. So comparing all of them, water will boil at lowest temperature at ooty, followed by Shimla, Mount Abu , New Delhi and Kochi. This is because , higher we go lower is the atmospheric pressure and lower is the point where water`s vapour pressure gets equal to the atmospheric pressure.

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X-ray crystallography helps to determine the atomic and molecular structure of a crystal. The crystalline structure performs the diffraction and it causes a beam of incident X-rays to diffract into many specific directions.

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To calculate the distance of the object from the source of sound based on the time taken for the echo, we can use the formula for distance traveled by sound:

Distance = (Speed of Sound × Time) / 2

The speed of sound in air at normal room temperature (20°C) is approximately 343 meters per second (m/s).

Given that the time taken in the echo is 5 seconds, we can plug the values into the formula:

Distance = (343 m/s × 5 s) / 2 Distance = 1715 meters / 2 Distance ≈ 857.5 meters

So, the approximate distance of the object from the source of sound is approximately 857.5 meters.

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When equal force acts for equal time, impulse (F × t) is equal. Impulse equals change in momentum, so both bodies gain same momentum regardless of their masses. Velocity and acceleration depend on mass, so they will differ.

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Edwin Hubble, an american astronomer, and was the first to prove that the universe is expanding. According to Expanding Universe theory, the universe is presently expanding. Hubble proved that there is a direct relationship between the speeds of distant galaxies and their distances from Earth. This is now known as Hubble’s Law.

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Joule is the unit of Pressure energy. Pressure energy is the energy stored in a fluid due to the force per unit area applied onto it Pressure energy = Pressure x volume Its dimensional formula is M L² T^-2

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The apparent weight of the body becomes zero in an elevator during free fall of a body under gravity. It can be said that the body becomes weightless as the force of reaction between the person and the plane with which he is in contact vanishes.

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Work done does not depend on the time for which the force was applied. Work done is only dependant on the force and displacement. Time is involved in the case of Power only