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Homework Help: From the nature of light unit

  1. Jan 22, 2010 #1
    1. The problem statement, all variables and given/known data

    Q: An electromagnetic radiation has a frequency of 5.00 x 10^14 Hz.
    a) Calculate its wavelength in a vacuum, in meters and nanometers.
    b) Calculate its wavelength in water.
    c) Is this radiation visible? If so, what is its colour?
    d) What is the index of refraction of a medium in which the speed of this radiation
    is 2.54 x 10^8 m/s?
    e) Where would you encounter this radiation in your daily life?

    I just need help with e)




    2. Relevant equations

    3. The attempt at a solution

    10. An electromagnetic radiation has a frequency of 5.00 x 1014 Hz.

    a) Calculate its wavelength in a vacuum, in meters and nanometers.

    Given: The speed of light in a vacuum is 3.00 x 108 m/s.

    Required: the wavelength of electromagnetic radiation, that has a frequency of 5.00 x 1014 Hz, in a vacuum, in meters and nanometers.

    Analysis: c=(f)(wavelength{vac}) and c=(n)(wavelength{med})
    Therefore wavelength(vac) = (n)(wavelength{med}) and wavelength(med) = wavelength(vac)/n

    Solution: λ = (3.00 x 108 m/s) / (5.00 x 1014 Hz)
    Λ = 6.00 x 10-7 m or 600nm

    b) Calculate its wavelength in water.

    Given: wavelength = 0.6 x 10^-6m or 600nm
    n = 1.33 for water

    Required: wavelength(med)

    Analysis: c=(f)(wavelength{vac}) and c=(n)(wavelength{med})
    therefore wavelength(vac) = (n)(wavelength{med}) and
    wavelength(med) = wavelength(vac)/n

    Solution: wavelength(med) = (0.6 x 10^-6m)/1.33
    = 4.51 x 10^-7 or 451 nm

    Phrase: The wavelength in water of an electromagnetic radiation, that has a frequency of 5.00 x 1014 Hz, is 451 nm

    c) Is the radiation visible? If so, what is its colour?

    Yes, the radiation is visible as orange (in a vacuum), since orange has a range of 590nm to 610nm on the spectrum and violet (in water), since violet has a range of 400nm – 450nm.

    d) What is the index of refraction of a medium in which the speed of this radiation is 2.54 x 108 m/s?

    Given:
    Speed of light: 3.00 x 108 m/s
    Speed of radiation in the medium: 2.54 x 108 m/s

    Required: the index of refraction.

    Analysys: n = speed of light in a vacuum/speed of light in a medium

    Solution: n = (3.00 x 108 m/s)/(2.54 x 108 m/s)
    n = 1.18

    e) Where would you encounter this radiation in your daily life?

    The only searches that come back to me are bronze....HELP!
     
  2. jcsd
  3. Jan 22, 2010 #2

    rock.freak667

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    Search for the electromagnetic spectrum and see what the frequency/wavelength corresponds to.
     
  4. Jan 22, 2010 #3
    I think it's between tv/fm radios and microwaves/radar? Am I wrong?
     
  5. Jan 22, 2010 #4
    was i wrong when i said bronze?
     
  6. Jan 22, 2010 #5

    rock.freak667

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    electromagnetic-spectrum.jpg


    Where does it lie now?
     
  7. Jan 22, 2010 #6
    In the visible light spectrum
     
  8. Jan 22, 2010 #7

    rock.freak667

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    then you'd encounter it as light from where?
     
  9. Jan 22, 2010 #8
    Hydrogen gas, neon gas, sodium or mercury vapour?
     
  10. Jan 22, 2010 #9

    rock.freak667

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    ....or from the sun...sunlight.
     
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