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95 Cards in this Set
- Front
- Back
Electromagnetic waves
a) do not transfer energy b) cannot propagate through a medium c) include sound waves d) none of the above |
d) none of the above
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Mechanical waves must have a ______ to propagate.
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medium
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Sound is a _______ wave.
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mechanical
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All waves transport _____.
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energy
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A mechanical wave implies an interaction between the wave and the ________.
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medium
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If a wave needs a medium to propagate, it is a _____ wave.
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mechanical
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If a wave does not need a medium to propagate, it is an ___ wave.
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electromagnetic
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Which of the following is not an example of an electromagnetic wave?
a) x-rays b) light c) sound d) heat e) television signals |
c) sound (sound is a mechanical wave)
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All waves are a(n) ______transfer most often through cyclical variations.
a) particle b) energy c) voltage d) temperature |
b) energy (waves are an energy transfer through cyclical variations)
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The naming of waves as mechanical is due to the physical interaction between the wave & the medium. The interaction produces 4 specific possible changes call acoustic variables:
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pressure
density temperature distance |
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All of the following are acceptable units of pressure except:
a) Pa b) lb/in squared c) kg/m squared d) lb/ft e) atm (atmospheres) f) mmHg (millimeters of mercury) |
d) lb/ft (pressure is a force per area - lb/ft is a force per distance)
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Density is defined as:
a) mass volume, kg/m cubed b) mass/volume, kg/m squared c) volume/mass, m cubed/kg d) mass X volume, m cubed kg |
a) mass/volume, kg/m cubed
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Sound is a _____, _____ wave.
a) longitudinal, electromagnetic b) longitudinal, mechanical c) transverse, electromagnetic d) transverse, mechanical |
b) longitudinal, mechanical
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For a longitudinal wave, the energy is transported by a series of _ and __ of the medium particles.
a) compression, heating b) rarefactions, reflections c) reflections, refractions d) compressions, rarefactions |
d) compressions, rarefactions
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Repetitious waves are a _____ transfer of ___________.
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cyclical, energy
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Cyclical means
a) periodic or repetitive b) in a circle c) linear |
a) periodic or repetitive
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The major classifications of waves are
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mechanical
electromagnetic |
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An electromagnetic wave does not need a ___ to propagate.
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medium
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Examples of electromagnetic waves are
a) TV, microwave, sound b) music, ultrasound, and ocean waves. c) x-rays, light, and microwaves |
c) x-rays, light, and microwaves.
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A ________ wave needs a medium to propagate.
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mechanical
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There can be no ________waves in a vacuum.
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mechanical
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A vacuum is the absence of a
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medium.
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There is no sound in a _____, since there is no medium.
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vacuum
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Two classifications of mechanical waves are
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transverse and longitudinal
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In a ___ wave, particle motion is perpendicular or "transverse" to the wave directions.
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transverse
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In a _______ wave, the particle motion is back and forth in the same direction as the wave propagation.
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longitudinal
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Sound is _____, mechanical wave.
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longitudinal
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A longitudinal wave has areas of ______ and compression.
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rarefaction
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An area of ______ is where the particles are farther apart than the normal state.
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rarefaction
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An area of ______is where the particles are closer together than the normal state.
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compression
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Not all waves need a ____ to propagate; _____ waves can operate in a vacuum.
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medium, electromagnetic
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__________ is a way of specifying how fast a wave is cyclically varying.
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Frequency
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The unit for frequency is ____, which is an abbreviation for cycles per __________.
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Hz, second
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Frequency has units which are the inverse of ________, or one divided by ________, also call Hz.
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time, second
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The number of times a longitudinal wave reaches maximum compression and rarefaction per time is called the ___________.
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period
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The reciprocal of frequency is the______
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period
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The period has units of
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time
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The reciprocal of the ______is frequency. Frequency has units of Hertz.
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period
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The ________ is the time between cycles of peak compression in a longitudinal wave, such as sound.
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period
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The ________ between cycles of peak compression is the same as the time between cycles of peak rarefaction
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time
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The ______ is the _________ between cycles of peak rarefaction
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period, time
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Frequency and period are _____.
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reciprocals
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The units for _____ and period are reciprocals.
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frequency
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Hertz and _______ (or seconds) are inversely related.
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time
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Since frequency and period are inversely related, if the frequency increases the period __________.
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decreases
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A shorter period means a higher ________.
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frequency
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A lower ___________ means a longer period.
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frequency
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The _______ is the physical measure of distance between wave peaks (maxima) or similarly wave (minima).
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wavelength
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Wavelength is a measure of ______ and therefore in the metric system has units of ___.
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distance, meters
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The period is a measure of ____ between peaks whereas the _______ is a measure of distance between peaks.
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time, wavelength
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Frequency and _______ are related throught the wave propagation velocity.
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wavelength
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The propagation _____ has units of m/sec.
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speed or velocity
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The __________ _______ is a measure of how fast a wave will travel.
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propagation speed
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The propagation velocity, (c), equals the frequency, (f), times the _________.
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wavelength
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For a given propagation velocity, if the frequency increases, the ______ must decrease.
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wavelength
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For a given propagation velocity, if the frequency _____, the ______ must increase.
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decreases, wavelength
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Frequency and wavelength have an _____relationship.
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inverse
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If the propagation velocity changes and the frequency is not changed the ___ must change.
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wavelength
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To determine the _____, the frequency and the propagation speed must be known.
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wavelength
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The frequency, wavelength and propagation speed are related together by the equation...
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wavelength = propagation speed / frequency
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The _______ of a signal is a measure of how big or loud it is.
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amplitude
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The _________ is determined as the maximum variation from the mean.
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amplitude
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The ________ is the same as the average.
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mean
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The ____ = maximum + minimum/ 2
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mean
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If the maximum is 20 and the minimum is 10, the mean is _
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15
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The difference between the max and the mean is the same as the difference between the mean and the ?
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minimum
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Since the amplitude equals the difference between the maximum and the mean, the ____ also equals the difference between the ____ and the minumum.
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amplitude, mean
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Amplitude is used to measure any wave variable. For sound waves, the units of amplitude will be any measure of the four ___ variables.
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acoustic
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A wave which has a physical interaction with the ______ is called a mechanical wave.
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medium
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A change within the ______ caused by a wave is a called a variable.
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medium
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For an acoustic wave, the changes caused to the medium are called ______ variables.
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acoustic
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There are ____ acoustic variables.
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4
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The four acoustic variables are:
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pressure
density distance ( particle displacement) temperature |
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Units of _____ are: Pascals, Atmospheres, mmHg, kg/m squared, lbs/ in squared
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pressure
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Units of __________ are: meters feet, miles, yards, etc.
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distance
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Units of ________ are mass/volume.
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density
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Changes in acoustic variables are the result of the mechanical interaction of the acoustic wave and the ____.
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medium
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What is the frequency, in Hz, of something that occurs 60 times in one minute?
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60 times/1 minute =
60 times/ 60 seconds = 1 time / 1 second = 1 Hz |
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What is the frequency, in Hz, of something that occurs 60 times in 0.5 seconds?
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60 times / 0.5 sec =
120 times / 1 sec = 120 Hz |
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What is the frequency, in Hz, of something that occurs 60 times in 0.1 seconds?
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60 times / 0.1 sec =
600 times / 1 sec = 600 Hz |
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What is the frequency, in Hz, of something that occurs 60 times in 1 hour?
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Since 1 hour = 60 minutes = 3600 seconds:
60 times/ 1 hour = 60 times/ 3,600 sec = 1/60 Hz |
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What determines the frequency of operation for ultrasound?
a) medium b) pulser c) patient d) wavelength |
b) pulser
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How much will the frequency change if the propagation speed changes by a factor of 2?
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Frequency will not change. Frequency is determined by by the source, not the properties of the medium.
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If the frequency is 1 MHz, what is the period?
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period = 1/ frequency
1/1 MHz = 1 usec |
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If the period is 0.5 useconds, what is the frequency/
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frequency = 1/period
1 / 0.5 usec = 1 / 0.5 MHz = 2 MHz |
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Which two of the following give the same info?
1) frequency = 10 kHz 2) frequency = 3 kHz 3) period = 0.1 msec 4) period = 10 ksec |
1 and 3
A 10 kHz frequency = a 0.1 msec period. |
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Since the period and the frequency are reciprocals, the period multiplied by the frequency equals __.
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one
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What determines the period for ultrasound?
a) medium b) pulser c) patient d) wavelength |
b) pulser
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How much will the period change if the propagation velocity changes by a factor of 2?
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The period will not change.
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If ultrasound travels 662 meters through air in 2 seconds, what is the propagation speed of sound in air in m/sec?
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331 m/sec
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How far can a car travel in 2 hours driving at 60 mph?
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120 mph
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How far can an ultrasound beam travel in soft tissue in 1 second?
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1540 m/sec
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How long would it take a car traveling 30 mph to travel 45 miles?
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1.5 hours
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How long would it take ultrasound in soft tissue to travel to a target 1 cm deep and back to the transducer?
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1540 m/sec or 13usec
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The speed of sound
a) changes w/ frequency b) changes w/ period c) depends on inertia and elasticity of medium |
c
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