US PHYSICS Flashcards
Sound waves
-Carry energy from one location to another
-Sound is a mechanical wave in which particles in the medium move.
-The molecules in the medium vibrate back and forth from a fixed position
- Cannot travel through a Vacuum
- It must travel through a medium where molecules are alternately compressed (squeezed together) and rarefied (stretched apart)
- Sound travels in a straight line
-Sound waves are longitudinal waves
Acoustic propagation properties
The effects of the medium upon the sound wave
Biological effect
The effects of the sound wave upon the biological tissue through which it passes
Acoustic variables
Pressure
Density
Distance
Pressure definition
Concentration of force in a area
Units pascals (Pa)
Density
Concentration of mass in a volume
Units: Kg/cm3
Distance
Measure of particle motion
Units: cm, feet, mile
Acoustic Parameters
Period
Frequency
Amplitude
Power
Intensity
Wavelength
Propagation Speed
Transverse wave
Particles move a direction that is perpendicular to the direction that the wave propagates.
Longitudinal wave
Same direction that the wave propagates
Sound is a longitudinal wave
In phase wave
When their peaks (max values) occur at the same time and at the same location
Similar the throughs of the wave (minimum value) occur at the same time and place
Synchronized marching band
Out of phase
Their peaks occur at different times and so do their throughs they are out of step.
Interference
More then one sound beam may travel in a medium and on occasion multiple beams may arrive at an identical location at exactly the same time.
Waves loose their individual characteristics at that moment and combine to form a single wave
Constructive interference
Interference of in phase wave results in formation of a single wave of greater amplitude them either of its components
Destructive interference
Pair out of phase wave
Results of an formation of a single wave of lesser amplitude than the least one of its components
When 2 out of phases waves are of equal amplitude, complete destructive interference may occur
Distance AKA
Particle Motion
Acústic variables need to have ritmic oscilación
Pressure
Density
Distance
Pressure
How much force you apply in one area
Units N/cm2
Density
How much mass we are able to concentrate in a volume
Units gr/cm3
Acoustic Variables
Pressure
Density
Distance
Acoustic Parameters
Period
Frequency
Amplitude
Intensity
Power
Propagation Speed
Wave length
Bigness Parameters
Amplitude
Power
Intensity
Periodo
Duracion de un ciclo
Periodo unidades
MS MICROSECONDS
Se puede ajustar el periodo
No ajustable por el operador
100% dependiente de la máquina
Frecuencia
La cantidad de ciclos en un segundo
Ciclos/ segundos
Frequency units
MHz
Millones de ciclo de un segundo
Periodo & Frequency relation
Son inversamente relacionados y recíprocos
Periodo y frequency
Ambos no se ajustan por el operador y ambos dependen 100% de la máquina de US
Amplitude definición y unidad
Altura de la onda
dB
Amplitude único parámetro acústico que se comporta como?
Variable
atenuación
Debilitamiento del sonido a medida que viaja por los tejidos
Intensidad def & unidades
Qué tan fuerte es una onda
mW/cm2
Milliwatts/Cm2
Intensidad directamente relacionado al power y indirectamente relacionado al?
Área
SATA stands for
Spatial Avarage Temporal Avarage
SPTA
Spatial Peak Tempo Avarage
SPTP
Spatial peak temporal peak
Valores de intensidad aprobado en USA se divide en:
Focus
Unfocused
Intensidades permitidas que no causen efectos dañinos
Unfocused 100mW/cm2 SPTA
Focused 1000 mW/cm2 SPTA
1W /Cm2
