us physics

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Author:
melissausp
ID:
70449
Filename:
us physics
Updated:
2011-03-03 12:43:35
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us physics
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Description:
chapter 2
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  1. name 4 acoustic variables
    • pressure
    • density
    • temperature
    • particle motion
  2. what is nyquist criteria
    • f(max)=f sampling
    • 2
  3. what is propigation velocity in soft tissue
    1540 m/s
  4. how many mu sec does it take sound to travel 1cm
    6.5 mu sec
  5. how long does it take to image to a depth of 1cm
    • 6.5 mu sec x 2cm (travel time)=
    • 13mu sec
  6. what is density represented by?
    p
  7. what is density equasion
    • density(p) = mass kg
    • volume m3
  8. What are the 4 wave parameters
    • frequency/period
    • wavelenght
    • propagation velocity
    • amplitude
  9. what is frequency/ period determined by and what are its units
    wave source

    cycles/second or HZ
  10. what is wavelength determined by
    wave source and medium

    any form of distance mm
  11. what is propagation velocity determined by and what are its units
    medium

    m/s
  12. what is amplitued determined by and what is its units
    • wave source but decreases with distance
    • volts or Decibels dB
  13. what is the equasion for wavelength
    • wavelenght = propigation velocity
    • frequency

    lamda= c/f
  14. define amplitude
    size, strength, or volume
  15. what is amplitued equasion
    max- mean

    mean-min

    • max-min
    • 2
  16. what is range of infrasound
    <20Hz
  17. What is range of Ultrasound
    >20 kHz
  18. What is range of audible sound
    20Hz-20kHz
  19. What is formula for bulk modulus?
    • stress
    • strain

    • change in pressure
    • change in volume
    • volume
  20. High bulk modulus material is
    • incompressible
    • inelastic
    • stiff
  21. low bulk modulus material is
    • compressible
    • elastic
    • not stiff
  22. what is equasion for prop v as related to Bulk modulus
    • c=square root of B mod
    • p (density)
  23. what is prop v in air
    331
  24. What is prop v in bone?
    4080 m/s
  25. what is prop v in soft tissue?
    1540 m/s
  26. what is prop v range for gases
    ie... air, helium, hydrogen
    331-1286 m/s
  27. what is prop v range for liquids
    ie... water, alcohol
    1130-1530 m/s
  28. what is prop v range for solids
    ie... lead, steel , diamonds
    1322- 12,000 m/s
  29. higher bulk modulus does what to prop v
    increase
  30. lower bulk modulus does what to prop v
    decreases
  31. power is directly proportional to
    voltage2 or Amplitude2
  32. What does the transmit power button control?
    changes the signals amplitude
  33. what are alternitive names for transmit power?
    • acoustic power
    • output power
    • transmit gain
    • power gain
    • output intensity
    • acoustic output
  34. intensity is directly proportional to what?
    power
  35. what is intensity equasion?
    • Intensity= power watts
    • Beam area m2

    • OR amplitude2
    • beam area
  36. what is the power equasion for dB
    • dB= 10 x log(Pf
    • Pi)

    • Pf is power final
    • pi is power initial
  37. what is the amplitude equasion for dB
    • dB= 20*log (Af)
    • Ai

    • af is amplitude final
    • ai is amplitude initial

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