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Electromagnetic Waves

  • Page ID
    32669
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    Electromagnetic waves are used to transmit long/short/FM wavelength radio waves, and TV/telephone/wireless signals or energies. They are also responsible for transmitting energy in the form of microwaves, infrared radiation (IR), visible light (VIS), ultraviolet light (UV), X-rays, and gamma rays. Each region of this spectrum plays an important part in our lives, and in the business involving communication technology. The list given above is in increasing frequency (or decreasing wavelength) order. Here again is the list of regions and the approximate wavelengths in them. For simplicity, we choose to give only the magnitudes of frequencies. That is we give log (frequency) (log(f)).
         Region: Radio, FM,  TV, microwave, IR, VIS, UV, X-rays, Gamma rays.
     Wavelength: 600 m  20 m   1 mc  1 mm 0.1 mm    1e-9 m    1e-12 m   1e-15 m
        log (f): 6   7   8   9 10  11   12   13  14  15    20      23
    

    Electromagnetic radiations are usually treated as wave motions. The electronic and magnetic fields oscillate in directions perpendicular to each other and to the direction of motion of the wave.

    The wavelength, the frequency, and the speed of light obey the following relationship:

    \(\mathrm{wavelength \times frequency = speed\: of\: light}\).

    The speed of light is usually represented by c, the wavelength by the lower case Greek letter lambda, \(\lambda\), and the frequency by lower case Greek letter nu \(\nu\). In these symbols, the above formula is:

    \(\lambda \nu = c\)

    The electromagnetic radiation is the foundation for radar, which is used for guidance and remote sensing for the study of the planet Earth.

    The Visible Spectrum

    Wavelengths of the visible region of the spectrum range from 700 nm for red light to 400 nm for violet light.

        red 700 nm
     orange 630
     yellow 550
      green 500
       blue 450
     violet 400
    

    There is no need to memorize these numbers, but knowing that the visible region has such a narrow range of 400-700 nm is handy at times when referring to certain light.

    Contributors and Attributions


    This page titled Electromagnetic Waves is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Chung (Peter) Chieh.

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