1. Which of the following is a mechanical wave?
(a) Radio-waves
(b) X-rays
(c) Light waves
(d) Sound waves
[Uttarakhand P.C.S. (Pre) 2016]
Ans. (d) Sound waves
- Sound travels in the form of vibrations through a material.
- These are called longitudinal mechanical waves.
- Radio, X-ray, and light waves are also types of waves, but they are made up of electromagnetic energy instead.
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2. An example of a longitudinal wave is :
(a) Radio wave
(b) Sound wave
(c) X-ray
(d) Gamma ray
(e) None of the above/More than one of the above
[66th B.P.S.C. (Pre) (Re. Exam) 2020]
Ans. (b) Sound wave
- Longitudinal waves need a material to move through.
- The bigger the amplitude of the sound wave, the louder it will be.
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3. Sound wave in air is –
(a) transverse
(b) longitudinal
(c) electromagnetic
(d) polarized
(e) None of the above/More than one of the above
[65th B.P.S.C. (Pre) 2019]
Ans. (b) longitudinal
- Sound travels through air (or any liquid) by making the particles of the medium vibrate in the same direction the sound is moving in.
- This type of wave is called a longitudinal wave.
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4. In a Sitar, which type of sound vibrations are produced?
(a) Progressive and Longitudinal
(b) Progressive and Transverse
(c) Stationary and Longitudinal
(d) Stationary and Transverse
[U.P. R.O./A.R.O. (Pre) 2021]
Ans. (d) Stationary and Transverse
- When we play a stringed instrument like a Sitar, we don’t just hear the sound of the string itself.
- The whole instrument vibrates and we hear the sound of this vibration.
- When a string is plucked, a wave of energy moves along it and is bounced back when it reaches the end.
- This creates a stationary wave.
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5. Long radio waves are reflected by which of the following layer of earth’s surface –
(a) Troposphere
(b) Ionosphere
(c) Tropopause
(d) Stratosphere
[U.P. P.C.S. (Pre) 1991]
Ans. (b) Ionosphere
- The ionosphere is an area of the Earth’s atmosphere from about 65 km to 400 km above the ground.
- It is made up of charged particles because of the sun’s radiation.
- It is important because it helps radio signals travel to far away places.
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6. Wireless communication is reflected back to the earth’s surface by the –
(a) Troposphere
(b) Stratosphere
(c) Ionosphere
(d) Exosphere
[U.P.P.C.S. (Pre) 1998]
Ans. (c) Ionosphere
- The ionosphere is a part of the Earth’s atmosphere that is located high up, between 48 and 965 kilometres above the ground.
- It helps bounce back wireless signals from the ground up.
- It is made up of parts of the thermosphere, mesosphere and exosphere.
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7. Which of the following atmospheric layers is responsible for the defection of radio waves?
(a) Troposphere
(b) Stratosphere
(c) Mesosphere
(d) Ionosphere
[U.P. Lower Sub. (Pre) 1998]
Ans. (d) Ionosphere
- The ionosphere is a part of the atmosphere located from 60 km to 1000 km from the ground.
- It is made up of ionized particles that can bounce back radio waves.
- This layer is created by the sun’s radiation.
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8. Waves of the Ultra High Frequency (UHF) range normally propagate by means of
(a) Ground waves
(b) Sky waves
(c) Space waves
(d) Surface waves
[R.A.S. / R.T.S. (Pre) 2018]
Ans. (c) Space waves
- Ultra-high frequency (UHF) is a term used by the ITU to refer to radio frequencies between 300 MHz and 3 GHz.
- These signals cannot travel along the ground or get reflected by the ionosphere.
- Instead, they are sent through the air in a direct line of sight, also known as space wave propagation.
- High frequency radio waves are also known as space waves.
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9. Which waves cannot be transmitted through a vacuum?
(a) Light
(b) Heat
(c) Sound
(d) Electromagnetic
[M.P.P.C.S. (Pre) 2000]
Ans. (c) Sound
- Sound waves can’t travel through empty space.
- They need something like a solid, liquid, or gas to move through.
- When sound travels it causes particles to vibrate and move in the same direction.
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10. Assertion (A): Radio waves bend in a magnetic field.
Reason (R): Radio waves are electromagnetic in nature.
Code :
(a) Both (A) and (R) are true, and (R) is the correct explanation of (A)
(b) Both (A) and (R) are true, but (R) is not the correct explanation of (A)
(c) (A) is true, but (R) is false
(d) (A) is false, but (R) is true
[I.A.S. (Pre) 2008]
Ans. (d) (A) is false, but (R) is true
- Radio waves are made of electricity and magnetism, so they usually aren’t affected by electric and magnetic fields.
- So, A false, but R is true.
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11. Cosmic rays –
(a) Are charged particles
(b) Are uncharged particles
(c) Can be charged as well as uncharged
(d) None of the above
[56th to 59th B.P.S.C. (Pre) 2015]
Ans. (a) Are charged particles
- Cosmic rays are not a type of light.
- They are very energetic particles that travel through space very quickly, almost as fast as light.
- They come from either the sun or from outside of our solar system.
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12. Which one of the following statements is not true about cosmic rays?
(a) They are electromagnetic waves
(b) They have very short wavelengths
(c) They are made of highly energetic charged particles
(d) They originate from the Sun
[U.P.P.C.S. (Pre) 2005]
Ans. (b) They have very short wavelengths
- Cosmic rays are made up of protons, helium and heavier nuclei which travel through space at nearly the speed of light.
- They have very high wavelengths, not short ones, which is not true.
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13. Which of the following does not require a medium?
(a) Radiation
(b) Convection
(c) Conduction
(d) None of these
[U.P. R.O./A.R.O. (Mains) 2017]
Ans. (a) Radiation
- In physics, radiation is the release of energy in the form of waves or particles through space or a medium.
- Types of radiation like radio waves, microwaves, infrared, visible light, X-rays and gamma rays do not need a medium to travel through.
- However, heat transmission through convection and conduction does need a medium.
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14. Which one of the following is associated with ‘Albedo’?
(a) Transmitting power
(b) Absorbing power
(c) Emissive power
(d) Reflecting power
[U.P.P.C.S. (Pre) 2019]
Ans. (d) Reflecting power
- Albedo is the amount of light or radiation that is bounced back from an object or area.
- Astronomers use albedo to measure how reflective planets, moons, and asteroids are.
- The level of albedo on Earth can be as high as 95% (0.95) for snow and as low as 3% (0.03) for water.
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15. What is the distance between two successive crests or successive troughs called?
(a) Amplitude
(b) Wavelength
(c) Frequency
(d) None of these
[45th B.P.S.C. (Pre) 2002]
Ans. (b) Wavelength
- The wavelength of a wave is the distance from one peak or valley to the next.
- This measurement is taken in the same direction as the wave.
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16. The velocity of electromagnetic waves is :
(a) 3 × 108ms–1
(b) 3 × 107ms–1
(c) 3 × 106ms–1
(d) 3 × 105ms–1
(e) None of the above/More than one of the above
[66th B.P.S.C. (Pre) 2020]
Ans. (a) 3 × 108ms–1
- The speed of all electromagnetic waves is always the same and is equal to the speed of light in a vacuum, which is about 3 × 108 ms–1.
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17. Which one is not an example of an electromagnetic wave?
(a) γ-rays
(b) X-rays
(c) Ultraviolet rays
(d) Supersonic waves
[Jharkhand P.C.S. (Pre) 2021]
Ans. (d) Supersonic waves
- Supersonic waves are not a type of electromagnetic wave, but Gamma-rays, X-rays and Ultraviolet rays are examples of supersonic waves.
- Supersonic refers to objects that move faster than the speed of sound.
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18. Which of the following has the longest wavelength?
(a) Infrared
(b) X-rays
(c) Visible light
(d) Radio waves
[R.A.S./R.T.S. (Pre) 1996]
Ans. (d) Radio waves
- The electromagnetic spectrum includes different types of electromagnetic radiation, like radio waves > microwaves > infrared light > visible light > ultraviolet > X-rays > and Gamma rays.
- Radio waves have the longest wavelengths, while Gamma rays have the shortest.
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19. Which of the following electromagnetic radiations has the maximum energy?
(a) Visible light
(b) Infrared rays
(c) Ultraviolet rays
(d) X-rays
[U.P. P.C.S. (Pre) 2018, U.P. P.C.S. (Mains) 2005]
Ans. (d) X-rays
- The energy of electromagnetic rays increases as the wavelength decreases.
- In terms of energy, the order of electromagnetic rays is as follows: Radio waves < Microwaves < Infrared < Visible light < Ultraviolet rays < X-rays < Gamma rays.
- It is evident that among the listed options, X-rays possess the highest level of energy compared to the others.
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20. Microwaves are electromagnetic waves having frequencies in the range of :
(a) 300 KHz – 3 MHz
(b) 3 MHz – 300 MHz
(c) 1 GHz – 300 GHz
(d) 300 GHz – 400 THz
[M.P. P.C.S. (Pre) 2020]
Ans. (c) 1 GHz – 300 GHz
- Microwave radiation is a type of electromagnetic energy that has wavelengths between one meter and one millimeter, and frequencies between 300 MHz and 300 GHz.
- Different sources have different definitions for what counts as microwave radiation, and this definition covers both UHF and EHF bands.
- Therefore, option (c) is the correct answer.
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21. Which one of the following is used for determining the structure of a crystal :
(a) Gamma rays
(b) X-rays
(c) UV rays
(d) visible lights
[R.A.S./R.T.S. (Pre) 1997-98]
Ans. (b) X-rays
- Crystallography is the study of crystals which are found in many forms in nature, from salt to snowflakes to precious stones.
- Crystallographers use the internal structure of these crystals to figure out how the atoms are arranged and to gain knowledge which is used by chemists, physicists and others.
- They use X-ray, neutron and electron diffraction methods to understand the features of solid materials.
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22. A radar which detects the presence of an enemy aircraft uses :
(a) Light waves
(b) Radio waves
(c) Sound waves
(d) Ultrasound waves
[Uttarakhand P.C.S. (Mains) 2002]
Ans. (b) Radio waves
- Radar is a way of finding where things are using radio waves.
- It is used to find the position of planes, boats, spaceships and cars.
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23. When there is a depletion of ozone in the stratosphere, the wavelength of radiation striking the earth’s surface will be –
(a) 10–10 m
(b) 10–7 m
(c) 10–2 m
(d) 100 m
[I.A.S. (Pre) 1993]
Ans. (b) 10–7 m
- Ultraviolet radiation is divided into three groups.
- UV-A radiation is a long wave radiation with a wavelength of 320-400 nm and is part of the sun’s rays.
- UV-B radiation is a medium wave radiation with a wavelength of 280-320 nm, and most of it is absorbed by the ozone layer but some make it to the earth’s surface.
- UV-C radiation has a wavelength of 100-280 nm.
- If the ozone layer in the stratosphere is depleted, the radiation striking the earth’s surface will be 100 nm.
- 1 nm = 1.0 × 10–9 m
- 100 nm = 100 × 10–9
- = 102× 10–9 = 10–7 m
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24. Which one of the following types of waves are used in a Night Vision apparatus?
(a) Radio waves
(b) Microwaves
(c) Infrared waves
(d) None of these
[I.A.S. (Pre) 2009]
Ans. (c) Infrared waves
- Infrared waves are types of electromagnetic energy with a longer wavelength than visible light.
- They are used in night vision equipment when it is too dark to see.
- Soldiers use infrared waves to locate targets, intruders, and hidden bombs, making it easier to identify the right targets for force.
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25. The waves used in common TV remote control are
(a) X-Rays
(b) Ultraviolet Rays
(c) Infrared Rays
(d) Gamma Rays
[R.A.S./R.T.S. (Pre) 2018]
Ans. (c) Infrared Rays
- Infrared light is often used in TV remotes.
- These remotes can be used to turn on and control TV sets, DVD players, and other household items.
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26. Which type of electromagnetic radiation is used in the remote control of a television?
(a) Infrared
(b) Ultraviolet
(c) Visible
(d) None of the above
[U.P.P.C.S.(Pre) 2013, U.P. U.D.A./L.D.A. (Pre) 2010, U.P.P.C.S (Pre) 2010, U.P.P.C.S. (Pre) 2002]
Ans. (a) Infrared
- Infrared radiation is the type of energy used in TV remotes.
- We cannot see infrared radiation because it has longer wavelengths than what we can see with our eyes.
- It is a type of energy that ranges from the red end of what we can see to microwaves.
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27. Which electromagnetic radiation is used in the remote control of a television?
(a) Infrared
(b) Ultraviolet
(c) Microwave
(d) None of the above
[Jharkhand P.C.S. (Pre) 2013]
Ans. (a) Infrared
- Infrared radiation is a type of light that we can’t see with our eyes.
- It has a wavelength that is longer than what we can see with the human eye.
- This type of radiation goes from the red end of what we can see to microwaves.
- It is used in TV remote controls.
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28. Which one of the following does a TV remote control unit use to operate a TV set?
(a) Light waves
(b) Sound saves
(c) Microwaves
(d) Radio waves
[U.P.P.C.S. (Mains) 2013, I.A.S. (Pre) 2000]
Ans. (d) Radio waves
- Infrared is a type of electromagnetic radiation that is used to send out radio and TV signals.
- Some of these signals are sent as radio waves instead.
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29. Waves used for telecommunication are –
(a) Visible light
(b) Infrared
(c) Ultraviolet
(d) Microwave
[U.P.P.C.S. (Mains) 2013]
Ans. (d) Microwave
- Microwaves are strong signals that range from 300 MHz to 300 GHz.
- They are able to carry a lot of channels at once, giving it many uses.
- It is often used for point to point communication.
- Telecommunications companies use it for both ground based relays and satellite communication.
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30. FM broadcasting service uses the range of frequency bands between –
(a) 109-139 MHz
(b) 54-75 MHz
(c) 76-87 MHz
(d) 88-108 MHz
[R.A.S/R.T.S. (Pre) 2013]
Ans. (d) 88-108 MHz
- FM radio stations use frequencies between 88 and 108 MHz.
- There are different allocations of these frequencies that are used around the world :
- 87.5 – 108 MHz – It is the ”standard” VHF FM band. The one which is most widely used around the globe.
- 76 – 90 MHz – This VHF FM band is used in Japan.
- 65.8 – 74.0 MHz – This VHF FM band is known as the OIRT band. It was used in Eastern Europe although few other countries such as Russia, Ukraine also use it.
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31. A radio station broadcast at 30-metre band. The frequency of the carrier wave transmitted by this station is:-
(a) 10 KHz
(b) 100 KHz
(c) 10 MHz
(d) 100 MHz
[R.A.S./R.T.S. (Pre) 1993]
Ans. (c) 10 MHz
- According to the formula n = c/1
- [ where n = frequency, c = speed of light; I = wavelength ]
- n = 3×108/30 = 10×106 = 10 MHz
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32. A layer in the Earth’s atmosphere called the Ionosphere facilitates radio communication. Why?
1. The presence of ozone causes the reflection of radio waves on Earth.
2. Radio waves have a very long wavelength.
Which of the statements given above is/are correct?
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2
[I.A.S. (Pre) 2011]
Ans. (d) Neither 1 nor 2
- Both answers are wrong in relation to the question.
- Radio waves have a very long wavelength, but the ionosphere, which has electrically charged ions, helps radios communicate.
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33. Television viewers using dish antennas to receive satellite signals do not receive signals during rain because :
1. of the small size of the antenna.
2. rain droplets absorb the energy of radio waves.
3. rain droplets disperse the energy of radio waves from their original direction.
Which of the above statements is correct?
(a) only 1
(b) only 1 and 2
(c) only 2 and 3
(d) 1, 2, and 3
[U.P.P.C.S. (Pre) 2017]
Ans. (d) 1, 2, and 3
- When it rains, radio waves can hit raindrops and turn into heat energy, which takes away the energy of the radio waves.
- Raindrops can also cause the radio waves to change direction, which makes it hard to get satellite signals.
- Radio signals become weaker during rain, which is why smaller antennas may not be able to pick them up.
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34. The following rays are used in the diagnosis of intestinal diseases :
(a) X-rays
(b) α-rays
(c) β-rays
(d) γ-rays
[43rd B.P.S.C. (Pre) 1999]
Ans. (a) X-rays
- X-rays are a type of energy waves that doctors use to look inside your intestines to check for any illnesses.
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35. CT Scan is done by using –
(a) Infrared Rays
(b) Ultrasonic Waves
(c) Visible Light
(d) X-Rays
[U.P.P.C.S. (Mains) 2011]
Ans. (d) X-Rays
- CT scans are special X-ray tests that take pictures of your body using X-rays and a computer.
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36. Which of the following was invented by Wilhelm Röntgen?
(a) Radio
(b) X-Ray Machine
(c) Electric Bulb
(d) None of the above
[U.P. P.C.S. (Pre) 2018]
Ans. (b) X-Ray Machine
- Wilhelm Röntgen discovered X-rays, which are a type of electromagnetic wave with a wavelength of between 0.01 and 10 nanometres. X-rays are widely used in medicine and industry.
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