Ch. 2 Physics: Sound Flashcards
What is a mechanical, longitudinal wave that moves through a medium as the result of vibrations?
Sound wave
True or false:
Sound requires a medium through which to travel.
True
True or false:
Sound can travel in a vacuum (space around us).
False
True or false:
The medium stays fixed.
True
Vibrations move from one location to the next.
Sound propagation
In ultrasound, what is the medium?
Body tissue or organs being imaged
True or false:
Sound waves travel in a straight line
True
What does sound carry?
Energy
What are sound waves also referred to as?
Acoustical waves
Particles of a medium move in the same direction (parallel) to the direction that the sound wave is propagating is called what?
Longitudinal waves
Particles of a medium move in a direction perpendicular to the direction of the sound wave is called what?
Transverse waves
True or false:
Sound waves are pressure waves.
True
How does the sound wave propagate through a medium?
By a series of compressions and rarefactions of molecules in the path of the sound.
What does it mean when the sound wave is compressed?
Squeezed together
What does it mean when the sound wave is rarefied?
Stretched apart
Acoustic propagation properties describes the effects of what upon a sound wave?
Medium
Will stiff tissue speed or slow the sound wave?
Speed up
Will air slow or speed up the sound wave?
Slow down
What effects the sound wave upon the tissue through which it passes?
Biological effects
Transmitted sound waves over tissues will heat up the tissue being imaged is an example of what?
Biological effects
What are the 3 acoustic variables?
Pressure
Density
Distance
If any of the acoustic variables have a rhythmic oscillation, then the wave is considered what?
A sound wave
What is the concentration of mass in a volume?
Density
What is the units for density?
kg/cm^3
What is the concentration of force in an area?
Pressure
What is the units for pressure?
pascals (Pa)
What is a measure of particle motion?
Distance
What are the units for distance?
cm
feet
mile
What does the acoustic parameters of a sound wave do?
Describe the features
What are the 7 acoustic parameters?
Frequency
Intensity
Power
Period
Propagation speed
Amplitude
Wavelength
What type of waves demonstrate matching “peaks and valleys”? They occur at the same places, at the same time.
In-phase waves
What types of waves demonstrate “peaks and valleys” occurring at different times and/ or different locations?
Out-of-phase waves
What occurs when multiple waves exist at the same time and location, then combine to form one wave?
Interference
What are the 2 types of interference?
Constructive
Destructive
What type of interference is two in-phase waves that result in a higher amplitude single wave?
Constructive
What typw of interference is two out-of-phase waves that result in a lower amplitude single wave?
Destructive
True or false:
When out-of-phase waves of equal amplitude interfere, they will concel each other out.
True
What is the result when waves of different frequencies interfere with each other?
Constructive and destructive interference
