Friday, 26 November 2021

10+2 PHYSICS; MCQ ON ELECTROMAGNETIC WAVES


Multiple Choice Questions

Choose the correct alternative. Each question is carrying one mark.

1. According to Maxwell's hypothesis, a changing electric field can give rise to :

  • (a) an e.m.f.
  • (b) electric current
  • (c) magnetic field
  • (d) electrical pressure.
  • (c) magnetic field


2. The velocity of light in vacuum is :

  • (a) √Ɛ₀𝛍₀
  • (b) Ɛ₀/𝛍₀
  • (c) √Ɛ₀/𝛍₀
  • (d) 1/√Ɛ₀/𝛍₀

  • (d) 1/√Ɛ₀/𝛍₀


3. Infrared part of electromagnetic spectrum lies in between :

  • (a) X-rays and ultraviolet
  • (b) visible and microwaves
  • (c) ultraviolet and visible
  • (d) microwaves and radiowaves.

  • (b) visible and microwaves


4. Which of the following is not electromagnetic waves ?

  • (a) UV rays
  • (b) 𝛾-rays
  • (c)𝛽 -rays
  • (d) X-rays.

  • (c) 𝛽-rays


5. Electric field and magnetic field in electromagnetic waves oscillate:

  • (a) in phase with each other
  • (b) out of phase with each other
  • (c) with phase difference of 𝜋/2
  • (d) parallel to each other.

  • (c) with phase difference of 𝜋/2


6. The dimensions of `\frac{1}{2}`Ɛ₀E² ( Ɛ₀ permittivity of free space, E = electric field) are :

  • (a) (ML T⁻¹ )
  • (b) (ML² T⁻² )
  • (c) (ML⁻¹ T⁻² )
  • (d)(ML² T⁻¹ )

  • (c) (ML⁻¹ T⁻² )


7. The Poynting vector is defined as :

  • (a) ĒXB
  • (b) E.B
  • (c) E.H
  • (d) E x H 
  • (a) ĒXH


8. Which rays are emitted by human body

  • (a) X ray
  • (b) Gamma ray
  • (c) Visible rays
  • (d) Infrared rays
  • (d) Infrared rays


9. For treating muscular sprain, we use:

  • (a) IR lamps
  • (b) UV lamps
  • (c) ordinary lamps 
  • (d) none of these.

  • (a) IR lamps


10. Choose the wrong statement.

  • (a) X-rays are used to detect fracture in bones.
  • (b) X-rays are of atomic origin.
  • (c) X-rays have wavelength of 1 µm.
  • (d) X-rays were discovered by W. Rontgen.

  • (c) X-rays have wavelength of 1 µm.


11. In microwave ovens, the frequency of microwaves is .......... resonant frequency of water molecules.

  • (a) equal to
  • (b) much greater than
  • (c) much smaller than 
  • (d) double of.

  • (a) equal to


12. The waves used in telecommunication are 

  • (a) Micro waves 
  • (b) Ultraviolet light 
  • (c) X-rays 
  • (d) 𝛾-rays

  • (a) Micro waves 


13. Displacement current is:

  • (a) produced when electric flux changes with time
  • (b) produced when magnetic flux changes with time
  • (c) cannot exist in vacuum
  • (d) not  a current at all. 
  • (a) produced when electric flux changes with time


14. Calculate the wavelength of electromagnetic waves of frequency 300 MHz.

  • (a) 3 m
  • (b) 2 m
  • (c) 30 m
  • (d) 1 m

  • (d) 1 m using formula   𝛌  =c/𝝂

15. From which layer of atmosphere, radio waves are reflected ?

  • (a) Ionosphere 
  • (b) Mesosphere
  • (c) Chromosphere 
  • (d) None of there

  • (a) Ionosphere 


16. The ionosphere can reflect which type of waves ?

  • (a) Microwaves 
  • (b) Radio waves
  • (c) X-rays
  • (d) 𝜸-rays

  • (b) Radio waves


17. If E and B are the electric and magnetic field vectors of e.m. waves, then the direction of

propagation of e.m. wave is along the direction of :

  • (a) E
  • (b) B
  • (c) E X B
  • (d) none of these.

  • (c) E X B


18. The speed of electromagnetic wave in a medium is same for :

  • (a) odd frequencies 
  • (b) even frequencies
  • (c) all frequencies 
  • (d) all intensities.

  • (c) all frequencies 


19. The amplitudes of electric and magnetic fields related to each other are :

  • (a) E₀ =  B₀
  • (b)  E₀ =  cB₀
  • (c) E₀ =  B₀/c
  • (d) E₀ =  c/B₀

  • (b)  E₀ =  cB₀



20. Which of the following has the longest wavelength ?

  • (a) Radio waves
  • (b) 𝜸-rays
  • (c) Microwaves 
  • (d) X-rays.

  • (a) Radio waves


21. Which of the following electromagnetic waves have smallest wavelength ?

  • (a) X-rays
  • (b) Radio waves
  • (c) Gamma rays 
  • (d) Microwaves

  • (c) Gamma rays 
The correct order of Increasing wavelengths  of em waves is gamma rays< X rays< UV rays< Visible light< Infra red waves< Micro Waves< Radio waves 


22. Production of electromagnetic waves is demonstrated by :

  • (a) Hertz
  • (b) Jagdish Chandra Bose
  • (c) Marconi
  • (d) Huygen

  • (a) Hertz


23. Which of the following have shortest frequency?

  • (a) microwaves
  • (b) visible light
  • (c) X-rays.
  • (c) 𝛄-rays

  • (a) microwaves

The correct order of decreasing frequencies of em waves is gamma rays> X rays> UV rays> Visible light> Infra red waves> Micro Waves> Radio waves 



24. If radio waves have wavelength of 150 m in vacuum, then its frequency is :

  • (a) 2 kHz
  • (b) 20 kHz
  • (c) 2 MHz
  • (d) 20 MHz.

  • (c) 2 MHz use formulae  𝝂 = C/𝜆


25. Which of the following e.m. radiation has the smallest wavelength ?

  • (a) Microwave 
  • (b) Ultra-violet
  • (c) X-rays
  • (d) Gamma rays

  • (d) Gamma rays


26. Unit of expression 𝝻₀Ɛ₀ are :

  • (a) ms⁻¹
  • (b) m⁻²s²
  • (c) sm⁻¹
  • (d) s²m²

  • (b) m⁻²s²


27. Ozone layer in atmosphere is useful because it :

  • (a) stops ultraviolet radiation
  • (b) stops greenhouse effect
  • (c) stops increase in temperature of atmosphere
  • (d) absorbs polluted gases


  • (a) stops ultraviolet radiation


28. Electromagnetic waves are transverse in nature and is evident by :

  • (a) interference 
  • (b) diffraction
  • (c) polarisation 
  • (d) reflection.

  • (c) polarisation 


29. The frequencies of X-rays, 𝜸-rays and ultraviolet rays are respectively a, b and c. Then :

  • (a) a<b, b>C
  • (b) a >b, b>c
  • (c) a >b, b<c 
  • (d) a <b, b< c.

  • (a) a<b, b>C


30. Which rays are not the portion of electromagnetic spectrum ?

  • (a) X-rays
  • (b) Microwaves
  • (c) 𝞪-rays
  • (d) Radio waves.

  • (c) 𝞪-rays


31. The electromagnetic waves do not transport:

  • (a) energy
  • (b) charge
  • (c) momentum 
  • (d) information.


  • (b) charge


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