chapter 1-3 Flashcards
frequency
cycles per second hertz
amplitude
Measures from middle or undisturbed, value to the maximum value
wavelength
distance or length of one complete cycle
human hearing
20hz-20kHz
high frequency
more cycles per second- better resolution but less penetration
lower frequency
less cycles per second- less resolution but more penetration
Pulse waves
pulse allow the ultrasound crystals to “talk” during the generation of sound and to “listen” between pulses
Unrelated
Two items that are not associated
related
two items that are associated or affiliated. Does not have to be specific
Directly related or directly proportional
two items that are associated such that when one item increases, the other increases. lower left to upper right
inversely related or inversely proportional
one item increases, the other decreases. upper left to lower right
reciprocal relationship
two numbers with a reciprocal relationship are multiplied together the result is 1. when one increases the other decreases
units of length
distance, circumference: cm, feet
units of area
cm2, ft2
units of volume
cm3, ft3
positive exponents has a value
greater than 10
negative exponents has a value
less than 1
exponents of zero has a value
Between 1 and 10
if we speak of frequency
talking about MEGAhertz
if we speak about period
talking about MICROseconds
tissue is also known as
media-medium
sound is a
mechanical wave
compressed
squeezed together
rarefield
stretched apart
sound travels in
a straight line
sound waves are
Longitudinal waves
Acoustic propagation propereties
effects of the medium upon the sound wave
biologic effects
effects of thee sound wave upon the biologic tissue through which it passes
what are the three acoustic variables
pressure, density, distance
Pressure
concentration of force in an area
what are the units of pressure
Pascals (Pa)
Density
concentration of mass in a volume
what are the units of density
kg/cm3
Distance
measure of particle motion
what are the units of distance
cm, feet, miles
sound waves are also known as
acoustic waves
Transverse waves
perpendicular to the direction that the wave propagates
longitudinal waves
particles move in the same direction that the wave propagates.
sound is what kind of wave?
Longitudinal wave
in-phase waves
when their peaks occur at the same time and at the same location. “in-step”
out-of-phase
their peaks occur at different times, so do their troughs. “out-of-step”
interference
waves lose their individual characteristics at that moment and combine to form a single wave
constructive interference
wave is larger than either of its comonents
destructive interference
resultant wave is smaller than one of its comonents
both constructive and destructive interference occur when
frequencies of the wave differ
parameters
describe features of a sound wave
source
a sound wave is the ultrasound system and transducer
Period
is the time it takes a wave to vibrate a single cycle