# physics

 The flashcards below were created by user lmarie on FreezingBlue Flashcards. The effects of the medium upon the sound wave. Acoustic Propagation Properties The effects of the sound wave on biologic tissue Biologic Effects Sound is what kind of wave? Mechanical, longitudinal Period- Definition? Determined by? Changed by sonographer? The time required to complete a single cycle determined by--source changed by sonographer--no Frequency- Definition? Units? Determined by? Changed by sonographer? Definition--The number of certain events that occur in a particular time durationUnits-- per second, hertz, HzDetermined by--SourceChanged by sonographer--no Ultrasound Range? Greater than 20,000Hz, not audible Audible Sound 20-20,000 Hz Infrasound? Less than 20 Hz Formula for intensity? I= power/areaI=w/cm2 Intensity is proportional to? Amplitude2 Formula for wavelength? wavelength (mm)= prop. speed (mm/us) / frequency (MHz) Formula for wavelength in soft tissue? wavelength= 1.54mm/frequency (MHz) Wavelength is determined by? Source and Medium Propagation speed is determined by? Medium only, density and stiffness Propagation Speed formula? speed= frequency x wavelength(m/s) =(Hz) x (m) In-Phase waves interfere how? Constructively Pulse duration formula? PD= number of cycles in pulse x period or PD=number of cycles in pulse / frequency Pulse Repetition Period definition? The time from the start of one pulse to the start of the next pulse. Includes "on time" and "off time" PRP Determined by? Changed by sonographer? Determined by-- sourceChanged by sonographer--yes(amount of listening time is determined by image depth) PRF definition? The number of pulses that occur in one second PRP formula? 1/ PRF PRF formula? 1/ PRP Depth and PRF are related how? Inversely proportional Depth and PRP are related how? directly proportional PRP x PRF = ?? 1 Duty Factor formula? DF = PD/PRP x 100 Duty Factor Definition? Determined by? Changed by sonographer? Definition-- The percentage of time the system is transmitting sound. (% of "on time")Determined by-- sourcechanged by sonographer--yes SPL formula? SPL= number of cycles x wavelength SPL determines resolution? Axial resolution PRP, PRF, and DF are all affected by what? Depth of view What intensity is most relevant with respect to tissue heating? SPTA What is the log of: a-100? b-10,000? a-2b-4(count the zeros) Authorlmarie ID16174 Card Setphysics DescriptionARDMS SPI Physics Review Updated2010-04-26T02:11:38Z Show Answers