Physics MCQs

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Myopia (short-sightedness) occurs when images are focused in front of the retina, causing distant objects to appear blurry. It is commonly due to an elongated eyeball or excessive corneal curvature. This defect is corrected using concave (diverging) lenses. Hyperopia, by contrast, focuses images behind the retina.

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In 1647 the French scientist Blaise Pascal (1623–1662) discovered that water exerts the same pressure in all directions. This statement is known as Pascal’s Principle.
Pascal’s law states that increase in pressure at a point in the enclosed liquid in equilibrium is transmitted equally in all directions in liquid and to the Walls of the container. The working of hydraulic lift, hydraulic press and hydraulic brakes are based on Pascal’s law.

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A fluorescent lamp tube is filled with a gas containing low pressure mercury vapor and argon, xenon, neon, or krypton. The pressure inside the lamp is around 0.3% of atmospheric pressure.

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Rheology is the study of the flow of matter, primarily in a liquid or gas state. It is related to Viscosity. In the science of rheology, a fluid’s changes are measured when there are actual forces (mechanical shear or pump pressure) induced.

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Modern engines also have, additionally, dynamic brake system which works on the principle of converting kinetic energy of the moving train to electricity making the electric motors to work as generators.

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When we press the top of bottle the pressure at top of the bottle decreases and hence, the velocity of liquid flow increases. Bernoulli’s Principle states that an increase in the speed of a fluid produces a decrease in pressure and that a decrease in the speed of a fluid produces an increase in pressure. The principle states that the total energy of a moving fluid remains constant at all times.

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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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The largest practical unit of mass is called as Chandra Shekhar Limit (C.S.L) which is equivalent to 1.4 times the mass of Sun. Chandrasekhar limit is the maximum mass theoretically possible for a stable white dwarf star. This limiting value was named after Indian-born astrophysicist Subrahmanyan Chandrasekhar, who formulated it in 1930. Using Albert Einstein’s special theory of relativity and the principles of quantum physics, Chandrasekhar showed that it is impossible for a white dwarf star, which is supported solely by a degenerate gas of electrons, to be stable if its mass is greater than 1.44 times the mass of the Sun.

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Kepler’s second law states that an imaginary line joining a planet and the sun sweeps out an equal area of space in equal amounts of time i.e. the areal velocity of the planet around the sun is constant. It is also known as Law of areas.

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If the speed of a satellite orbiting close to the earth is made √2 times (or increased by 41%) then it will escape from the gravitational field. Moon is a natural satellite of earth.