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26 Cards in this Set
- Front
- Back
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period
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time to complete one cycle units: sec, hours, microsec determined by: source adjustable: no (unless transducer is changed) formula: 1/f |
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frequency
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number of complete cycles in 1 sec units: hertz (per second) determined by: source adjustable: no formula: 1/t |
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1 hertz
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1 cycle per sec
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1 kHz
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1000 cycles per sec
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1 MHz
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1,000,000 cycles per sec
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infrasound
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less than 20 Hz
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audible sound
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between 20 Hz to 20 kHz
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ultrasound
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greater than 20 kHz
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relationship bw period and frequency
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*inversely related frequency increases period decreases frequency decreases period increases *reciprocal: period x frequency= 1 |
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Three bigness parameters |
Amplitude Power Intensity |
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Amplitude |
Bigness of a sound wave Calculated by= max - average Units: decibels dB Determined by: source Adjustable: yes |
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Peak to peak amplitude |
The difference between max-min |
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Power |
Rate of energy transfer or rated work is performed -strength and bigness Units: dB or watts Determined by: source Adjustable: yes |
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How are amplitude and power related |
Directly One increases the other does too Power=amp(2) |
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Intensity |
Concentration of energy in a sound beam -strength and bigness Units: watts/cm(2) Determined by: source Adjustable: yes Formula: power/area If Intensity and power increase area decreases |
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Adjusting 1 bigness |
The other 2 will be adjusted by the machine |
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How are power and intensity related |
Directly related |
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How are intesity and amplitude related |
Directly Intensity= amplitude(2)
Ex: 4 = 2x2
When amplitude is doubled intensity increases 4 times (quadrupled) |
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Another name for wavelength |
Lambda |
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Wavelength |
Distance or length of one complete cycle -units: distance units. Cm, mm, meters -determined by:source and medium Adjustable: no Formula: c/f Note: lower frequency higher lambda |
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Wavelength=c/f |
C=propogation speed F=frequency -in soft tissue speed is constant -if frequency increases wavelength decreases 1.54 mm/microsec= c
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Period and wavelength |
Directly related |
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Propagation speed |
Rate at which sound wave travels through the medium -units: m/sec or mm/microsec Determined by: medium Adjustable:no Formula: distance /time |
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2 characteristics of a medium affect the speed of sound |
Stiffness Density -stiffness and speed are directly related -density and speed are inversely related |
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Stiffness |
Ability of an object to resist compression -ping pong ball stiff -marshmallow is not |
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Density |
Relative weight of a material -rock sinks -wood will not |
