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Electromagnetic Waves Model Question Paper

12th Standard

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Physics

Time : 01:00:00 Hrs
Total Marks : 50
    5 x 1 = 5
  1. The electric and the magnetic fields, associated with an electromagnetic wave, propagating along negative X axis can be represented by _____.

    (a)

    \(\vec { E } ={ E }_{ 0 }\hat { i } \) and \(\vec { B } ={ B }_{ 0 }\hat { k } \)

    (b)

    \(\vec { E } ={ E }_{ 0 }\hat { k } \) and \(\vec { B } ={ B }_{ 0 }\hat { j } \)

    (c)

    \(\vec { E } ={ E }_{ 0 }\hat { i } \) and \(\vec { B } ={ B }_{ 0 }\hat { j } \)

    (d)

    \(\vec { E } ={ E }_{ 0 }\hat { j } \) and \(\vec { B } ={ B }_{ 0 }\hat { i } \)

  2. During the propagation of electromagnetic waves in a medium __________________.

    (a)

    electric energy density is double of the magnetic energy density

    (b)

    electric energy density is half of the magnetic energy density

    (c)

    electric energy density is equal to the magnetic energy density

    (d)

    both electric and magnetic energy densities are zero

  3. Which one of them is used to produce a propagating electromagnetic wave?

    (a)

    an accelerating charge

    (b)

    a charge moving at constant velocity

    (c)

    a stationary charge

    (d)

    an uncharged particle

  4. Which of the following E.M waves has the longest wavelength?

    (a)

    Radio waves

    (b)

    IR

    (c)

    X-rays

    (d)

    visible

  5. If the velocity of light in a medium is 2.25 x 108 ms-1 then the refractive index of the medium will be _______________.

    (a)

    1.5

    (b)

    0.5

    (c)

    1.33

    (d)

    1.73

  6. 5 x 2 = 10
  7. What are electromagnetic waves?

  8. What is meant by Fraunhofer lines?

  9. Write the uses of Micro waves.

  10. Which part of Electromagnetic is absorbed from sunlight by ozone layer?
    (i) Write its source and
    (ii) mention its uses.

  11. What is the orgin of displacement currtent?

  12. 5 x 3 = 15
  13. Explain the Maxwell’s modification of Ampere’s circuital law.

  14. Write down the properties of electromagnetic waves.

  15. Discuss the source of electromagnetic waves.

  16. Identify the Electromagnetic waves whose wavelength vary as
    (a) 10-12 m to 10-8 m
    (b) 10-4 m and write their uses.

  17. Identify the following Electromagnetic radiations
    (a) 109 Hz
    (b) 1011 Hz. Give one application of each.

  18. 4 x 5 = 20
  19. Consider a parallel plate capacitor whose plates are closely spaced. Let R be the radius of the plates and the current in the wire connected to the plates is 5 A, calculate the displacement current through the surface passing between the plates by directly calculating the rate of change of flux of electric field through the surface.

  20. Let an electromagnetic wave propagate along the x-direction, the magnetic field oscillates at a frequency of 1010 Hz and has an amplitude of 10−5 T, acting along the y-direction. Then, compute the wavelength of the wave. Also write down the expression for electric field in this case.

  21. The magnetic field amplitude of an Electromagnetic wave is 1.6 x 10-7 T. If the frequency is 30 MHz. determine electric field, any velocity K and λ.

  22. In an electric circuit, there is a capacitor of reactance 100 Ω connected across the source of 220 V, find the displacement current.

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