Waves Flashcards
What is a surface wave?
Which particles of the medium undergo a circular motion. Surface waves are neither longitudinal nor transverse
What is the motion of surface waves?
It is only the particles at the surface of the medium that undergo the circular motion. The motion of particles tends to decrease as one proceeds further from the surface.
What is a wave?
A moving disturbance in the energy level of a field.
What is medium?
The material or empty space through which signals, waves or forces pass.
What is direction of propagation?
The axis along which the wave travels.
Wave motion transfers _________ from one point to another, usually without permanent displacement of the particles of the medium-that is, with little or no associated mass transport
Energy
Describe the motion of waves in general.
In physics a wave can be thought of as a disturbance or oscillation that travels through space-time, accompanied by a transfer of energy.
What are the two types of basic waves?
transverse & longitudinal waves
What is a transverse wave?
Composed of up-and-down movement-each end of the medium move up-and-down while the wave moves horizontally
Transverse wave: Particles of the medium move in a direction_________to the direction that the wave moves
perpendicular
What is longitudinal waves?
Composed of back-and-forth movement along the direction of the wave-each end of the medium moves horizontal as well as the wave
What type of motion is present in a longitudinal waves?
no up-and-down motion
Longitudinal waves: Particles of the medium move in a direction__________to the direction that the wave moves
parallel
What is frequency?
Waves per second; measured in cycles per second
What is Wave length?
Distance from one wave top (crest) to the next
What is period or phase shift?
How far the wave “slides”
What is amplitude?
Height of the wave
What is speed?
Measured in meters per second
What is wave part?
Crest is the wave top, trough is the wave bottom
What is frequency measured in?
Hertz (Hz)
What is pressure waves?
Can be reflected, refracted, diffracted, or absorbed (interfered) by other waves
What is reflection?
Waves reflect off of a medium at the same but opposite angle; the angle of incidence is the angle at which a wave strikes a medium
What is Refraction?
Redirection due to contact with a new medium
What is Diffraction?
Spreading or scattering; bending around an object
What is interference or absorption?
Waves may interfere with other waves or be absorbed by matter.
What are additive when waves interfere?
Amplitudes
What is constructive interference?
When the crest of one wave passes through the crest of another wave or the trough of one wave passes through the trough of another wave, and the resultant wave is greater.
Constructive interference: Addition of two positive amplitudes or two negative amplitudes results in a _________ or _________
greater value or wave height
What is destructive interference?
when the crest of one wave passes through the trough of another wave.
Destructive interference: Amplitudes from one crest are added to the negative amplitudes from the other wave’s trough, and the ___________
height of the resultant wave is decreased
What is another name for sound waves?
Pressure waves
What is sound waves?
pressure fluctuations that deviate from ambient pressure
How are sound waves measured?
Pascals
What is sound pressures?
measured on a sound pressure level that uses a logarithmic decibel scale to narrow the wide range (20 Hz to 20 kHz) of amplitudes audible to the human ear.
What is the wide range of decibel scale that are audible to the human ear?
(20 Hz to 20 kHz
What type of waves are sound waves?
longitudinal waves that propagate through matter (solid, liquid, gas) at varying speeds
What determines the speed of sound waves?
medium’s elastic modulus (stiffness), density, and temperature
The speed of sound through air at 0°C is ______________.
740 miles per hour
What happens to sound waves when there is no matter?
In the absence of matter, there are no sound waves.
Sound waves do not exist in a vacuum, and only travel through _________.
matter
What is ultrasonography?
Sound waves above the auditory limit of the human ear (20 kHz)
What does ultrasonography penetrate?
These waves have power to penetrate different tissues of the body at different speed and reflect back from the tissue interface
What types of waves are used during ultrasonography?
Ultrasound waves to construct a visual image of internal structures by examining the reflection of sound
What are useful procedures that ultrasonography can assist with (3)?
intravenous catheter insertion, blocks, or transesophageal echocardiography (TEE)
Describe the function of ultrasonography.
a signal generator that transmits sound waves through tissues and a transducer to record the time delay for the returning reflected sound waves
What is the relationship between speed of sound waves and tissues?
Unique and constant to specific tissue compositions, and therefore the time delay of the returning reflected sound waves allows calculation of the location of different internal structures.