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physics
midterm
| interfaces that scatter ultrasound energy are | usually equal to or smaller than the wavelength |
| regions of lower pressure and density is | rarefactions |
| if you switch to a lower frequency for penetration what happens to the wavelength | the wavelength of the transducer increases |
| attenuation of 5-mhz transducer at a depth of 4cm is | 10.DB |
| With high transducer frequency what happens to the rayleigh scattering | it also becomes high |
| Is 15.0khz an ultrasound frequency | No |
| Duty factor will increase with | pulse repetition frequency, pulse duration and perio |
| the attenuation of a 5mhz transducer in a soft tissue would be 5.0db at how many centimeters | 2cm depth |
| what is the period for a 5.0mhz transducer in soft tissue | 0.2us |
| impedance is equal to | density x propagation speed |
| Continuous wave Doppler has a duty factor of | 100% |
| Perpendicular incidence the angle is | 90 degrees |
| attenuation decreases with and increase in the | wavelength |
| average propagation speed in human soft tissue is | 1.54mm/us |
| Frequency is ________proportional to the wavelength | inversely |
| the distance to a reflector in soft tissue is | 15cm and 195.0 us is the round-trip time to this depth |
| what is period | the time it takes for one cycle to occur |
| what happens in an oblique incident | sound is refracted at the boundary between two media and the propagation speed is different |
| the propagation speed in soft tissue is not | 1.54 m/s |
| Snells law is related to | the transmitted beam and incident beam direction and the speed of sound in two material forming interface |
| what is the pulse repetition frequency | number of pulse in a second |
| when frequency increase, what happens to the period | it decreases |
| amplitude is | the maximum variation that occurs in an acoustic variable |
| 3db of attenuation mean | 1/2 the original intensity |
| if the beam power increases what happens to intensity | it will increase |
| what is propagation speed | its the speed at which the wave travels through a medium |
| what Is sound | a mechanical longitudinal wave |
| the wave length of a 3mhz ultrasound in soft tissue is | .51 mm |
| CW is not described by what | pulse duration |
| what is frequency | the number of complete cycles per second |
| what is it called when sound travels and reduction in amplitude and the intensity of the wave happens | attenuation |
| propagation speed is higher in ____ than soft tissue | bone |
| sound requires ____ to travel through | a medium |
| ultrasound pulses contain a range of frequencies called | bandwidth |
| Duty factor is | unitless |
| Spatial pulse length does not increase with | frequency |
| What are acoustic parameters | cycle, period, frequency |
| the factor of time that the pulsed ultrasound is on is called | duty factor |
| what is pulse repetition frequency | the number of pulses occurring in 1 second |
| Attenuation is higher in _____than soft tissue | bone |
| Compression is an acoustic variable | false |
| best way to describe ultrasound scattering | allows us to see the tissue interfaces |
| the distance to the reflector in soft tissue with a round-trip of 39 | 30cm |
| if the beam area decrease what happens to intensity | it increases |
| List the four intensities in order | SPTP< SATP<SPTA<SATA |
| Heat production depends mostly on | TA intensities |
| Continuous wave is best described by what terms | frequency wavelength and propagation speed |
| that rate at which energy passes through a unit is called | intensity |
| propagation speed is primarily determined by | the stiffness of the medium |
| the unit for impedance is | rayl |
| in oblique incidence, the incident and reflection angels are | always equal |
| if frequency increase, period will_____ | decrease |
| stiffer media has lower speed of sound | false, its higher |
| Intensity is equal to | the power of the wave divided by the area over which the power is spread |
| .20khz is equal to | 20,000hz |
| 500hz is equal to | .500khz |
| the impedance of media determines how much of the____ | sound wave is reflected and transmitted into the sound beam |
| Attention three encompasses | absorption scattering and reflection |
| Spatial pulse length is not determined by | the length of the pulse and the propagation speed |
| impedance increases when | density and propagation speed increases |
| pulse duration will not increase with | frequency |
| what does sound travel through | air lungs and bone |
| what can sound not travel through | vacuum |
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