CMI 350 Exam 1 with all Correct & 100% Verified Answers
|Latest Version |Already Graded A+
velocity ✔Correct Answer--speed of a fluid moving from one location to another
-units: distance divided by time (ex: cm/s)
frequency ✔Correct Answer--the number of particular events that occur in a specific duration
of time (in US, the frequency of a wave is described as the # of cycles that occurs in 1 second)
-units: Hz, units of per second (1/second)
-determined by the sound source only
-not adjustable
-infrasound: < 20 Hz
-audible sound: 20 Hz - 20 kHz
-ultrasound: >20kHz
-inversely related to period and wavelength
wavelength ✔Correct Answer--distance or length of one complete cycle
-units: mm, m, or any other unit of length
-in soft tissue: 0.1 - 0.8 mm
-determined by the source and the medium
-not adjustable
-inversely related to frequency
scattering ✔Correct Answer--random redirection of sound in may directions
-occurs when the tissue interface is small-less than or equal to the wavelength of the incidence
of the sound beam
-higher frequency scatter more; directly related to frequency
absorption ✔Correct Answer--occurs when ultrasonic energy is converted into another energy
form, such as heat
-directly related to frequency; higher frequency waves attenuate more than lower frequency
refraction ✔Correct Answer--a change in direction of wave propagation when traveling from
one medium to another
-occurs only if 2 conditions are satisfied: 1. oblique incidence (not normal) 2. different
propagation speeds of the 2 media
reflection ✔Correct Answer--sound strikes a boundary and returns back to the sound source
(transducer)
-specular reflection: when the boundary is smooth, the sound is reflected in only 1 direction in
an organized manner
-diffuse reflection: wave reflects off an irregular surface, it radiates in more than one direction
, amplitude ✔Correct Answer--"bigness" of a wave; difference between the maximum and
minimum value and the average value of an acoustic variable
-units: pascals, g/cm^3, any distance (cm, in, etc), and decibels (dB)
intensity ✔Correct Answer--the concentration of energy in a sound beam
-units: W/cm^2
-ranges 0.01 - 300 W/cm^2
-determined by the sound source only
-adjustable
-power (w)/area (cm^2) = intensity
power ✔Correct Answer--the rate of energy transfer or the rate at which work is performed;
describes "bigness" of a wave
-units: watts (W)
-ranges 0.004 - 0.090 W
-determined by sound source
-adjustable
-as power increases amplitude increases; proportional to the amplitude squared
temporal average intensity ✔Correct Answer--averaging the intensity during the entire pulse
repetition period (PRP)--both the transmit and receive times
-the lowest of all temporal intensities
calculate the US for sound to go from the surface of the skin to a reflector in the soft tissue
✔Correct Answer-
SPTA means ✔Correct Answer--spatial peak, temporal average
-the most relevant intensity with respect to tissue heating
what is spatial pulse length and how is it determined? ✔Correct Answer--the distance that a
pulse occupies in space from the start to the end of a pulse
-units: mm
-determined by source and medium
-not adjustable
-spatial pulse length (mm) = #cycles x wavelength (mm)
-directly proportional to the # of cycles in the pulse and wavelength
-inversely proportional to frequency
frequencies of sound ✔Correct Answer-infrasound - less than 20 Hz
audible sound - 20 Hz - 20 kHz
ultrasound - greater than 20 kHz
velocity of the common list of substances ✔Correct Answer-lung: 500
|Latest Version |Already Graded A+
velocity ✔Correct Answer--speed of a fluid moving from one location to another
-units: distance divided by time (ex: cm/s)
frequency ✔Correct Answer--the number of particular events that occur in a specific duration
of time (in US, the frequency of a wave is described as the # of cycles that occurs in 1 second)
-units: Hz, units of per second (1/second)
-determined by the sound source only
-not adjustable
-infrasound: < 20 Hz
-audible sound: 20 Hz - 20 kHz
-ultrasound: >20kHz
-inversely related to period and wavelength
wavelength ✔Correct Answer--distance or length of one complete cycle
-units: mm, m, or any other unit of length
-in soft tissue: 0.1 - 0.8 mm
-determined by the source and the medium
-not adjustable
-inversely related to frequency
scattering ✔Correct Answer--random redirection of sound in may directions
-occurs when the tissue interface is small-less than or equal to the wavelength of the incidence
of the sound beam
-higher frequency scatter more; directly related to frequency
absorption ✔Correct Answer--occurs when ultrasonic energy is converted into another energy
form, such as heat
-directly related to frequency; higher frequency waves attenuate more than lower frequency
refraction ✔Correct Answer--a change in direction of wave propagation when traveling from
one medium to another
-occurs only if 2 conditions are satisfied: 1. oblique incidence (not normal) 2. different
propagation speeds of the 2 media
reflection ✔Correct Answer--sound strikes a boundary and returns back to the sound source
(transducer)
-specular reflection: when the boundary is smooth, the sound is reflected in only 1 direction in
an organized manner
-diffuse reflection: wave reflects off an irregular surface, it radiates in more than one direction
, amplitude ✔Correct Answer--"bigness" of a wave; difference between the maximum and
minimum value and the average value of an acoustic variable
-units: pascals, g/cm^3, any distance (cm, in, etc), and decibels (dB)
intensity ✔Correct Answer--the concentration of energy in a sound beam
-units: W/cm^2
-ranges 0.01 - 300 W/cm^2
-determined by the sound source only
-adjustable
-power (w)/area (cm^2) = intensity
power ✔Correct Answer--the rate of energy transfer or the rate at which work is performed;
describes "bigness" of a wave
-units: watts (W)
-ranges 0.004 - 0.090 W
-determined by sound source
-adjustable
-as power increases amplitude increases; proportional to the amplitude squared
temporal average intensity ✔Correct Answer--averaging the intensity during the entire pulse
repetition period (PRP)--both the transmit and receive times
-the lowest of all temporal intensities
calculate the US for sound to go from the surface of the skin to a reflector in the soft tissue
✔Correct Answer-
SPTA means ✔Correct Answer--spatial peak, temporal average
-the most relevant intensity with respect to tissue heating
what is spatial pulse length and how is it determined? ✔Correct Answer--the distance that a
pulse occupies in space from the start to the end of a pulse
-units: mm
-determined by source and medium
-not adjustable
-spatial pulse length (mm) = #cycles x wavelength (mm)
-directly proportional to the # of cycles in the pulse and wavelength
-inversely proportional to frequency
frequencies of sound ✔Correct Answer-infrasound - less than 20 Hz
audible sound - 20 Hz - 20 kHz
ultrasound - greater than 20 kHz
velocity of the common list of substances ✔Correct Answer-lung: 500
