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42 Cards in this Set
- Front
- Back
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Sound is a mechanical, longitudinal wave. True or false?
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True
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Areas of increased pressure and density
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Compressions
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Areas of decreased pressure and density
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Rarefaction
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Concentration of force within an area, force/area
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Pressure
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The effects of the sound wave upon the biologic tissue
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Biologic effect
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The effects of the medium upon the sound wave
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Acoustic propagation properties
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Particles move in a perpendicular direction to the direction of the wave
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Transverse wave
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Particles movie in the same direction as the wave
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Longitudinal wave
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What are the 3 acoustic variables ?
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Pressure , density , and distance
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What are the 7 parameters that describe sound waves ?
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Period, frequency, amplitude, power, intensity, wavelength, speed
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The time required to complete a single cycle
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Period
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Time from the start of a cycle to the start of the next cycle.
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Period
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Number of certain events that occur in a particular time duration
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Frequency
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Typical values for frequency ?
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2 MHz to 15 MHz
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Affects penetration and axial resolution
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Frequency
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Heard by man, frequencies between 20hz and 20,000hz
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Audible sound
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Waves with frequency exceeding 20,000 hz .
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Ultrasound
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Sound with frequencies less than 20hz
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Infrasound
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When related to each other, period and frequency are ?
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Reciprocals
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Frequency goes up, period ____
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Goes up
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Shorter period = ___ frequency ?
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Higher
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What are the 3 bigness parameters ?
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Amplitude, power, intensity
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Difference between the average value and the maximum value of an acoustic variable . The variation of an acoustic variable
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Amplitude
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The rate that work is performed or the rate of energy transfer
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Power
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Power is ___ to the waves amplitude squared?
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Proportional
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Power ____ as sound propagates through the body.
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Decreases
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If the amplitude is doubled, the power is ____ by a factor of four ?
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Increased
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The concentration of energy in a sound beam. The beams power divided by the beams cross sectional area .
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Intensity
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Watts / cm2 is the equation for?
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Intensity
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Intensity is ____, or _____, to the power.
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Proportional , directly related
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If power is doubles what is the intensity ?
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Doubled
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Can all 3 bigness parameters be changed by the sonographer ?
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Yes
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The length or distance of a single cycle.
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Wavelength
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Propagation speed
------------————— Frequency Is the equation for |
Wavelength
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Higher frequency = ____ wavelength ?
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Shorter
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The rate that sound travels through a medium.
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Propagation speed
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Stiffness and speed are what direction ?
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Same
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Density and speed what directions ?
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Opposite
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What is related to weight ?
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Density
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What is related to change in shape ?
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Stiffness
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Speed and wavelength are ___ related
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Direcrly
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Sound in a slow medium has a ____ wavelength
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Short
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