electromagnetic spectrum.txt

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electromagnetic spectrum.txt
2011-10-18 16:15:02

lecture 6 and 7 (10-13-11, 10-18-11)
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  1. A change in the magnetic field always induces or creates what?
    electric field
  2. A change in the electric field always induces or creates what?
    magnetic field
  3. The changing electric or magnetic fields are repetitive, and do what?
    oscillate forming waves
  4. What is an electromagnetic wave?
    patterns of magentic and electric fields changing
  5. What speed do electromagnetic waves travel at?
    speed of light
  6. Do all waves travel at the same frequency and wavelength?
  7. What changes as waves form a spectrum and the frequencies and wavelengths change?
    physical effects change also
  8. What are some examples of the physical effects we manipulate in therapy to treat patients?
    • visibility
    • heat
    • chemical effects
    • radio/television transmission
  9. What is the electromagnetic spectrum?
    graphic representation of the range of wavelength of energy including radiant energy, visible, ultraviolet, and infrared
  10. What is the length of one wave made by one oscillation?
  11. What type of electromagnetic waves have the longest wavelength? (lower frequency)
  12. What waves have shorter wavelengths? (higher frequency)
    infrared, visible, ultraviolet
  13. What has the shortest wavelength and highest frequency of all?
    gamma rays
  14. What are wavelengths measured in?
  15. What is frequency?
    number of oscillations per second
  16. What is frequency measured in?
    hertz (Hz)
  17. What are hertz?
    cycles per second
  18. If a wavelength is longer, what is the frequency?
    lower frequency
  19. If the wavelength is shorter, what is the frequency?
    higher frequency
  20. What type of wavelength gives the deepest penetration?
    longer wavelength
  21. What type of frequency gives the deepest penetration?
    lower frequency
  22. What type of frequency gives superficial penetration?
    higher frequency
  23. In the electromagnetic spectrum, what waves have the highest frequency?
    • 1.cosmic rays
    • 2. gamma rays
    • 3. x-rays
    • 4. ultraviolet

    *these are like treble, higher and not as deep
  24. What is in the middle of the spectrum?
    visible light

    • violet - higher frequency
    • red - lower frequency
  25. What waves on the spectrum have lower frequencies?
    • 1. microwaves
    • 2. radar
    • 3. shortwaves / radiowaves

    *like bass, deeper and lower
  26. 1 Hz equals what?
    1 cycle per second
  27. Different wavelengths and frequencies form different what?
    physical effects
  28. What is a medium?
    environment energy is going through
  29. Radiant energy can be effected by a medium in what 4 ways?
    • 1. absorbed (what we want)
    • 2. reflected (bounce off body, dont affect tissues)
    • 3. refracted (ends up at different angle)
    • 4. passes right through (has no affect at all)
  30. What law states that electromagnetic waves must be absorbed in order to produce effects?
    grotthus draper law
  31. What is the cosine law?
    maximum absorption is going to occur at a right angle to the surface of the skin
  32. What is the inverse square law?
    the intensity of the energy is inversely proportional to the distance of the source

    • *if distance is greater the intensity is less,
    • *if the distance is smaller, the intensity is greater
  33. What law states waves change direction sometimes while passing through certain mediums (snells law)?
    law of refraction
  34. What law states energy that is absorbed is used, but not all the energy is absorbed?
    law of absorption