Physics Soundwaves Part 1 Flashcards
traveling
Propagating
the capability to do work
energy
propagating variation
wave
A _____ is a propagating disturbance that moves energy from one location to another
wave
_____ is a wave
sound
Sound is a particular type of _____
wave
Quantities of these variations are called acoustic variables
- _____
- _____
- Particle _____
- _____
density
pressure
motion
temperature
Particles _____ back and forth as sound waves travel through the medium
oscillate
Sound waves require a _____
medium
They cannot travel through a _____
vacuum
Sound is a mechanical _____ (compression) wave
longitudinal
P waves are _____ waves
longitudinal
S waves are _____ waves
transverse
Components of an Ultrasound Wave
- Compression
- Region of _____ pressure and _____ in a longitudinal wave
- Corresponds to a sine wave _____ - Rarefaction
- Region of _____ pressure and _____ in a longitudinal wave
- Corresponds to a sine wave _____ - Cycle - _____ complete variation of an acoustic variable
- Y Axis - typically represents _____ (strength) of an acoustic variable
- X Axis -typically represents _____ or _____
high density peak low density trough one amplitude time distance
Wave Parameters
- _____
- _____
- _____
Frequency
Period
Wavelength
_____ = The number of cycles that occur in one second
frequency
Frequency
Determined by the _____ source
Affects _____ and _____ Resolution
sound
penetration
axial
Frequency
_____/_____ = 1 Hertz
_____ Hz = 1 kHz
_____ Hz = 1 MHz
Humans are capable of hearing frequencies between _____ and _____ Hz
cycle second 1,000 1,000,000 20 20,000
Frequency
Frequencies > _____Hz = ULTRASOUND
Typical in Diagnostic Medical Ultrasound
___-___ MHz through ___-___ MHz
Great _____ = Lousy _____ resolution
Great _____ resolution = Lousy _____
Limits defined by
_____ resolution and _____
20,000 1-2 10-20 penetration axial axial penetration axial penetration
Frequency
Frequency (Hz) = 1/___(sec)
_____ and _____ are RECIPROCALS
Higher frequency = lower period
period
period
frequency
Frequency
Frequency _____ = Period _____
Period _____ = Frequency _____
Period and Frequency are _____ proportional
increases decreases increases decrease inversely
Period
Length of time to complete _____ cycle
Time from start of _____ cycle to start of the next cycle
Determined by the _____ SOURCE
one
one
SOUND
Period
Unit = _____, (microsecond)
second
Period
Period = 1/____ (MHz)
_____ and _____ are RECIPROCALS
frequency
period
frequency
Period
Period _____ = Frequency _____
Period _____ = Frequency _____
Period and Frequency are _____ proportional
decreases increases increases decrease inversely
Wavelength
_____ of space over which one cycle occurs
Determined by _____ source and _____
length
sound
medium
Wavelength
Unit = _____, mm (any distance measurement)
1 mm = _____ m
Common US wavelength in ST (Soft Tissue) _____-_____ mm
meters
- 001
- 1
- 8
Wavelength
Wavelength (mm) = Propagation _____/_____ (MHz)
Wavelength = c/f
For Soft Tissue:
Wavelength = _____/_____ (MHz)
speed frequency c f 1.54 frequency
Wavelength
If: Wavelength = _____/_____
As:
Wavelength _____ - Frequency _____
Wavelength _____ - Frequency _____
c f increase decrease decrease increase
Wavelength
Wavelength and Frequency are _____ proportional
Inversely
Propagation Speed a.k.a. Acoustic Velocity
_____ = is the RATE at which sound travels through a medium
vs
_____ = is the RATE AND DIRECTION at which sound travels through a medium
speed
velocity
Sound Source = _____ and _____
Medium = Propagation _____
Sound Source and Medium = _____
frequency, period
speed
wavelength
Propagation _____ = The speed at which sound can travel through a medium
Units: _____/_____
Determined ONLY by the _____
speed
meters
second
MEDIUM
Propagation Speed
All _____, regardless of _____, travels at the same speed through any specific medium
Speed of sound in SOFT TISSUE
1.54 km/s 1,540 m/s 1.54 mm/ms 3,500 mph
sound
frequency
Propagation Speed
Propagation Speed (m/s) = _____(Hz) x _____(meters)
frequency
wavelength
Propagation Speed
What is it about the medium that determines propagation speed?
Medium _____ and _____
_____ is the resistance of a material to compression
_____ is the concentration of matter
stiffness
density
stiffness
density
Propagation Speed
Rule of Thumb:
Stiffness _____ - Speed _____
Density _____ - Speed _____
increases
increases
increases
decreases
Propagation Speed
Associated with stiffness are 2 additional factors
_____ and _____
_____ is the ability of an object to return to its original space and volume after a force is no longer acting on it
-opposite of stiffness-
_____ if the fractional decreases in volume when pressure is applied
-opposite of stiffness-
elasticity
compressibility
elasticity
compressibility
