Test: Physics - UPSC MCQ

(i) There is no significant production of silicon wafers in India (as of 2011). So unlikely that it became 3rd largest by 2017-18. So, #1 is wrong.
(ii) Tariffs are determined under the Electricity Act. Any entity with "Corporation" word is irrelevant. so, #2 is wrong.

(i) 2010: International Team of Astronomers confirmed Albert Einstein's theory of general relativity and that the expansion of the universe is accelerating after looking at data from the Hubble Space Telescope.
There is an unknown source of energy in the universe which is causing the cosmic expansion to speed up.
(ii) 2016: Japanese researchers' study finds that the expansion of the universe could be explained by a cosmological constant, as proposed by Einstein in his theory of general relativity. So second statement is right. This eliminates B and (C)
(iii) 2018: Hubble Space Telescope captured image of a phenomenon called Einstein Ring. Einstein in his theory of general relativity, had suggested that a massive object would warp space and time. So, statement 3 is right. Hence we are left with correct answer "D": 1, 2 and 3 all correct. 

Indian Remote Sensing (IRS) satellites are used in Assessment of crop productivity, Locating ground-water resources and Mineral exploration. This system was launched in 1979 and 1981. This system is used in agriculture, water resources, forestry and ecology, geology, marine fisheries and coastal management. It is the largest constellation of the remote sensing satellites.

The discovery of Higgs boson is important because it explains why sub atomic particles have mass.  According to the scientists, Higgs boson is the only particle which explains how the basic building blocks of matter interact.

Gravity is the feeble force among the four.

Thunder storms result from the rapid upward movement of warm, moist air. They can occur inside warm, moist air masses and at fronts. As the warm, moist air moves upward, it cools, condenses, and forms cumulonimbus clouds that can reach heights of over 20 km (12.45 miles). The thunderstorms are associated with the cumulonimbus clouds. These clouds normally form on warm sunny days but they can also be found on cold front. But this question is asking about the Thunder i.e. the sound produced. The lightning generates between 100 million and 1 billion volts of electricity and can heat the air to around 50K°F. The rapid expansion causes the shock waves.
Thunder happens because the lightning would heat the air at huge temperatures and the air expands so fast that it make a loud clap of thunder.

Formation of rainbow involves all dispersion, refraction and internal reflection.

Size of the Sun at dusk is an optical illusion because of atmospheric refraction. Colour of the sun appears yellow due to scattering whereas pure sunlight is white in colour. Twinkling of stars is an optical illusion. Air whirlpools make the stars twinkle.

Ball bearings are used to reduce friction and friction is directly proportional to effective surface area. So if effective surface area is reduced then friction will also reduce.

1. It would be difficult to use a kerosene lamp
2. The blotting paper would fail to function
3. The big trees that we see around would not have grown on the Earth

An artificial satellite moving round the Earth in a circular orbit possesses an acceleration which is “constant” in magnitude but “changing in direction”. An artificial satellite revolves round the earth under centripetal acceleration. By the launch rocket, immediately before the satellite is established in the predetermined orbit, the speed given to it is 30, 000 km/hr. The speed must be great enough so gravity doesn’t bring the satellite back to Earth, but not so great that the satellite escapes gravity out into space. This means that the speed, which is provided by the rocket is the source of the centrifugal force, and the attraction of the earth holds it from moving away from this centrifugal force.

A geostationary orbit (or Geostationary Earth Orbit -GEO) is a geosynchronous orbit directly above the Earth's equator (0° latitude), with a period equal to the Earth's rotational period and an orbital eccentricity of approximately zero. It is the part of space about 35, 786 km (22, 236 miles) above sea level, in the plane of the equator, where near geostationary orbits may be implemented.

In the above figure, dotted line shows the reflected beam of light from mirror OP₂.

The anomalous expension of water as it cools from 4°C to 0°C means that the density of water is greatest at 4°C. So the ice that forms in cold weather forms at the top of the water (where the less dense coldest water gathers) and then acts as an insulating barrier preventing the water underneath from getting much colder (because heat cannot escape).