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Electromagnetic waves Model Question Paper

12th Standard

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Physics

Time : 02:00:00 Hrs
Total Marks : 60
    10 x 1 = 10
  1. The dimension of \(\frac { 1 }{ { \mu }_{ 0 }{ \varepsilon }_{ 0 } } \) is _____.

    (a)

    [LT-1]

    (b)

    [L2T-2]

    (c)

    [L-1T]

    (d)

    [L-2T2]

  2. Which of the following is false for electromagnetic waves

    (a)

    transverse

    (b)

    non-mechanical waves

    (c)

    longitudinal

    (d)

    produced by accelerating charges

  3. 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 \(\vec { B } ={ B }_{ 0 }\hat { i } \)

  4. In an electromagnetic wave traveling in free space the rms value of the electric field is 3 V m−1. The peak value of the magnetic field is _____.

    (a)

    1.414 x 10-8 T

    (b)

    1.0 x 10-8 T

    (c)

    2.828 x 10-8 T

    (d)

    2.0 x 10-8 T

  5. Which of the following is an electromagnetic wave?

    (a)

    α - rays

    (b)

    β - rays

    (c)

    \(\gamma\) - rays

    (d)

    all of them

  6. If E = Eo sin[106 x -ωt] be the electric field of a plane electromagnetic wave, the value of ω is_____.

    (a)

    0.3 x 10−14 rad s−1

    (b)

    3 x 10−14 rad s−1

    (c)

    0.3 x 1014 rad s−1

    (d)

    3 x 1014 rad s-1

  7. The electric and magnetic fields of an electromagnetic wave are _____.

    (a)

    in phase and perpendicular to each other

    (b)

    out of phase and not perpendicular to each other

    (c)

    in phase and not perpendicular to each other

    (d)

    out of phase and perpendicular to each other

  8. Electromagnetic waves are produced by _____________.

    (a)

    static charge

    (b)

    moving charge

    (c)

    an accelerating charge

    (d)

    chargeless particles

  9. The EM waves do not transport _______________.

    (a)

    energy

    (b)

    charge

    (c)

    momentum

    (d)

    information

  10. A magnetic field is produced by ____________.

    (a)

    a changing electric field

    (b)

    a moving charge

    (c)

    both of them

    (d)

    none of them

  11. 5 x 1 = 5
  12. Radio waves

  13. (1)

    1 x 10-1m to 1 x 104m

  14. I - R Radiation

  15. (2)

    Spectrum of Carbon Arc

  16. Continuous Emission spectra

  17. (3)

    Incandescent solids

  18. Line Absorption spectra

  19. (4)

    Solar spectrum

  20. Fraunhofer Lines

  21. (5)

    8 x 10-7 m to 5 x 1Q-3m

    2 x 2 = 4
  22. Assertion: Electromagnetic waves carries not only energy and momentum but also angular momentum.
    Reason: Electromagnetic waves cannot be polarized.
    Codes: 
    (a) Assertion and Reason are correct and Reason is the correct explanation of Assertion.
    (b) Assertion and Reason are true but Reason is the false explanation of the Assertion.
    (c) Assertion is true but Reason is false.
    (d) Assertion is false but Reason is true.

  23. Assertion: Microwaves do not obey reflection and polarization.
    Reason: Gamma rays are used in radiotherapy for cancer treatment.
    Codes: 
    (a) Assertion and Reason are correct and Reason is the correct explanation of Assertion.
    (b) Assertion and Reason are true but Reason is the false explanation of the Assertion.
    (c) Assertion is true but Reason is false.
    (d) Assertion is false but Reason is true.

  24. 8 x 2 = 16
  25. What is displacement current?

  26. What are electromagnetic waves?

  27. Write down the integral form of modified Ampere’s circuital law.

  28. What is meant by Fraunhofer lines?

  29. Write the uses of Radio waves.

  30. Why are Infrared radiation referred to as heatwaves? Name the radiations, which are next to these radiation having
    (i) shorter λ
    (ii) longer λ.

  31. Draw a diagram depicting oscillating electric and magnetic field of an electromagnetic wave.

  32. What is the orgin of displacement currtent?

  33. 5 x 3 = 15
  34. Explain the Maxwell’s modification of Ampere’s circuital law.

  35. Write down the properties of electromagnetic waves.

  36. Explain the types of emission spectrum.

  37. Explain the types of absorption spectrum.

  38. Write the uses of Infrared radiation

  39. 2 x 5 = 10
  40. Compute the speed of the electromagnetic wave in a medium if the amplitude of electric and magnetic fields are 3 x 104 N C–1 and 2 x 10–4 T, respectively.

  41. A pulse of light of duration 10−6 s is absorbed completely by a small object initially at rest. If the power of the pulse is 60\(\times\) 10−3 W. Calculate the final momentum of the object.

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