HPSC MCQ Series: Physics Part-IV
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HPSC MCQ Series: Physics Part-IV

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Physics Multiple Choice Questions For HCS Exam

Haryana Civil Services Exam 2020

Important 20000 MCQ Series For HCS Exam: PHYSICS PART-IV

Q1. The term ‘equinox’ means

(a) The path which the Earth takes around the Sun

(b) The axis of the Earth around which it rotates

(c) When the day and night are of equal duration

(d) The time when the Sun seems to be going round and round in the sky in the Arctic but does not go below the horizon

Ans: (c) When the day and night are of equal duration

Explanation: The time when the sun crosses the plane of the earth's equator, making night and day of approximately equal length all over the earth and occurring about March 21 (vernal equinox or spring equinox) and September 22 (autumnal equinox) . 

Q2. Heat from the Sun reaches the Earth by

(a) Reflection

(b) Conduction

(c) Radiation

(d) Convection

Ans: (c) Radiation

Explanation: The sun heats the earth through radiation. Since there is no medium (like the gas in our atmosphere) in space, radiation is the primary way that heat travels in space. When the heat reaches the earth it warms the molecules of the atmosphere, and they warm other molecules and so on.

Q3. In which of the following cases, kinetic energy is being used in performing work?

(a) Paddling the bicycle to cover a distance

(b) Driving a car to cover a distance

(c)   grinding wheat grain

(d) Rowing a boat in the lake

Ans: (b) Driving a car to cover a distance

Explanation: Kinetic energy is the energy an object has because of its motion. If we want to accelerate an object, then we must apply a force.After work has been done,energy has been transferred to the object, and the object will be moving with a new constant spee(d) Thus  Driving a car to cover a distance kinetic energy is being used in performing work.

Q4. Which of the following parts of the sunlight makes the solar cooker hot?

(a) Ultra violet

(b) Red light

(c) Infrared

(d) Cosmic rays

Ans: (c) Infrared

Explanation: A solar cooker lets the UV light rays in and then converts them to longer infrared light rays that cannot escape. An effective solar cooker will use the energy of the sun to heat a cooking vessel and efficiently retain the energy (heat) for maximum cooking effectiveness.

Q5. If the velocity-time graph of a particle is represented by y = mt + c, then the particle is moving with:

(a) constant speed

(b) constant velocity

(c) constant acceleration

(d) varying acceleration

Ans: (c) constant acceleration

Explanation: If the velocity-time graph of a particle is represented by y = mt + c, then the particle is moving with constant acceleration.

Q6. Which of the following occurred first?

(a) Albert Einstein propounded the General Theory of Relativity

(b) Max Planck unveiled the Quantum Theory 

(c) Guglielmo Marconi sent out the first wireless signals

(d) Wright Brothers successfully flew an aircraft

Ans: (c) Guglielmo Marconi sent out the first wireless signals

Q7. A passenger standing in a bus is thrown outward when the bus takes a sudden turn. This happens due to

(a) Outward pull on him

(b) Inertia of motion

(c) Change in momentum

(d) Change in acceleration

Ans: (b) Inertia of motion

Explanation: It’s because of inertia, which is simply the tendency of any body to continue on whatever path it’s travelling unless acted on by an external force. For a standing passenger, his/her body will tend to continue along the straight line route the bus was travelling before the sharp turn. As the passenger’s feet are fairly firmly located to the floor of the bus when it turns, a force will act upon the passenger’s feet accelerating them towards the centre of the turn. The result? The feet no longer be under the centre of gravity of the passenger and he/she will appear to fall outwards. 

Q8. When pressure is increased the melting point of ice

(a) increases

(b) does not change

(c) decreases

(d) depends on the impurities in the ice

Ans: (c) decreases

Explanation:

if you increase the pressure on the ice the ice-water system wants to try to lower it again. It can do that by making itself fit into a smaller volume. But since water fills a smaller volume when it's liquid, rather than solid, it will go to a lower melting point -- allowing more solid to become liqui(d)

Q9. Longitudinal waves cannot travel through

(a) Vacuum

(b) Solid

(c) Liquid

(d) Gas

Ans: (a) Vacuum

Explanation:  The reason sound can't travel through a vacuum is that sound needs a medium (solid, liquid or gas with real vibrating molecules) and not because it is a longitudinal wave' 

Q10. Electrostatic precipitator is used to control the pollution of

(a) air

(b) water

(c) noise

(d) thermal

Ans: (a) air

Explanation:  Originally designed for recovery of valuable industrial-process materials, electrostatic precipitators are used for air pollution control, particularly for removing particles from waste gases at industrial facilities and power-generating stations.

Q11. Tungsten is used for the manufacture of the filament of an electric bulb, because

(a) It is a good conductor

(b) It is economical

(c) It is malleable

(d) It has a very high melting point 

Ans: (d) It has a very high melting point

Explanation: Bulb as you know gets heated up,so tungsten which has the highest melting point and low thermal expansion is used as a filament which avoids any variations in the brightness of the bulb as the temperature increases.

Q12. What is the wavelength of visible spectrum? 

(a) 1300A -3000A

(b) 3900A  -7600 A

(c) 7800 A -8000 A

(d) 8500 A -9800 A

Ans: (b) 3900A  -7600 A

Explanation: Visible light ranges from about 4,000 angstroms to 7,000 angstroms. In fact, the colors that make up visible light, like red, blue and green, and their complements violet, yellow, and orange, also have their own ranges of wavelength.

Q13. Who measured the velocity, of light first?

(a) Galileo

(b) Newton

(c) Romer 

(d) Einstein

Ans: (c) Romer

Explanation: Measuring the Speed of Light with Jupiter's Moons. The first real measurement of the speed of light came about half a century later, in 1676, by a Danish astronomer,Ole Römer.

Q14. When a vehicle passes, TV reception gets distorted This is because

(a) metal reflects radio waves

(b) spark plug creates electromagnetic disturbances

(c) vehicle pollution affects the performance of the TV components

(d) modern vehicles use electro ignition system

Ans: (b) spark plug creates electromagnetic disturbances

Explanation: It is called multipath interference. What happens is that in addition to the direct transmission, you get a second signal that is reflected off the passing vehicle and which interferes with the primary signal.

Q15. The energy emitted by the Sun is due to

(a) Chemical reaction

(b) Nuclear fission

(c) Nuclear fusion

(d) All of the above

Ans: (b) Nuclear fission

Explanation: The sun is a medium, yellow star, consisting primarily of hydrogen at temperatures high enough to cause nuclear fusion. Nuclear fusion is a nuclear reaction in which hydrogen nuclei fuse together to form helium nuclei and release energy.

Q16. The Sky appears blue because of

(a) Atmospheric water vapour

(b) Scattering of light

(c) Reflection on sea water

(d) Emision of blue wavelength by the sun

Ans: (b) Scattering of light

Explanation: Blue light is scattered in all directions by the tiny molecules of air in Earth's atmosphere. Blue is scattered more than other colors because it travels as shorter, smaller waves. 

Q17. Dynamo is a device for converting

(a) Heat energy into electrical energy

(b) Mechanical energy into electrical energy

(c) Magnetic energy into electrical energy

(d) Chemical energy into electrical energy

Ans: (b) Mechanical energy into electrical energy

Explanation: A dynamo is an electric generator that produces direct current using a commutator. A commutator is a device that reverses the direction of current. Thedynamo uses wire coils that rotate creating a magnetic field. This action converts the mechanical energy of the rotation to a direct electric current.

Q18. Oil rises up the wick in a lamp because

(a) Oil is very light

(b) Of the diffusion of oil through the wick

(c) Of the surface tension phenomenon

(d) Of the capillary action phenomenon

Ans: (d) Of the capillary action phenomenon

Explanation: It's due to capillary action.

Capillary action is the ability of a liquid to flow in narrow spaces without the assistance of, or even in opposition to, external forces like gravity.

Q19. In the atmosphere ultraviolet rays are absorbed by

(a) Oxygen

(b) Nitrogen

(c) Ozone

(d) Helium

Ans: (a) Oxygen

Explanation: Most of the ultraviolet radiation in sunlight is absorbed by oxygen in Earth's atmosphere, which forms the ozone layer of the lower stratosphere. Of the ultraviolet that does reach Earth's surface, almost 99 percent is UVA radiation.

Q20. Which of the following metals is used for the manufacture of heating elements provided in electric iron?

(a) Nickel

(b) Chromium

(c) Nichrome

(d) Tungsten
Ans: (c) Nichrome

Explanation: Nichrome: Most resistance wire heating elements use nichrome 80/20 (80% nickel, 20% chromium) wire, ribbon, or strip. Nichrome 80/20 is an ideal material, because it has relatively high resistance and forms an adherent layer of chromium oxide when it is heated for the first time

Q21. An electron microscope gives higher magnification than an optical microscope, because:

(a) it uses more powerful lenses

(b) the velocity of electron is smaller than that of visible light

(c) the electrons have more energy than the light particles

(d) the wavelength of electrons is smaller as compared to the wavelength of visible light

Ans: (d) the wavelength of electrons is smaller as compared to the wavelength of visible light

Explanation: An electron microscope gives higher magnification than an optical microscope because  the wavelength of electrons is smaller as compared to the wavelength of visible light

Q22. The hydraulic brakes used in automobiles is a direct application of:

(a) Archimedes’ principle

(b) Torieellian law

(c) Bernoulli’s theorem

(d) Pascal’s law

Ans: (d) Pascal’s law

Explanation: Hydraulic brakes work on the principle of Pascal's law. According to this law whenever pressure is applied on a fluid it travels uniformly in all the directions. Therefore when we apply force on a small piston, pressure gets created which is transmitted through the fluid to a larger piston.

Q23. Where are mesons found?

(a) Cosmic rays

(b) X-rays

(c) Gamma rays

(d) Laser beam

Ans: (a) Cosmic rays

Explanation: Outside the nucleus, mesons appear in nature only as short-lived products of very high-energy collisions between particles made of quarks, such as cosmic rays (high-energy protons and neutrons) and ordinary matter.

Q24. Plants are dried up in winter due to frost because

(a) Evaporation does not take place

(b) Photosynthesis does not take place at such low temperature

(c) Respiration does not take place at low temperature

(d) There is mechanical loss of tissues and drought condition prevails

Ans: (d) There is mechanical loss of tissues and drought condition prevails

Explanation: Plants are dried up in winter due to frost because there is mechanical loss of tissues and drought condition prevails

Q25. For a body moving with non-uniform velocity and uniform acceleration

(a) Displacement -Time graph is linear

(b) Displacement-Time graph is non-linear

(c) Velocity -Time graph is nonlinear

(d) Velocity-Time graph is linear

Ans: (b) Displacement-Time graph is non-linear

Explanation: a body is said to be moving with the uniform velocity when it has no acceleration, which means that neither the speed nor the direction of the object are changing with respect to time while the body is said to be moving with the non-uniform velocity.

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