Understanding ultrasound physics Exam
Review Questions & Answers
50. What is the range of periods commonly found in waves produced by
ultrasound systems?
A. 0.001 to 1s
B. 0.06 to 0.5 us
C. 0.2 to 1 ms
D. 10 to 100 ns - -B. Ultrasonic imaging waves have a period in ps. The
period is the range of 0.06 to 0.5 the time of a single cycle. Period is the
loolto reciprocal of frequency. A wave with a frequency of 2 MHz has a period
of 0.5 usec. A wave with a frequency of 15 MHz has a period of 0.06 us.
- 51. With standard ultrasonic imaging, what happens to the period of a
wave as it propagates?
A. increases
B. decreases
C. remains the same - -C. Certain parameters of a wave change as the wave
travels through the body. However, the period and the frquency of a wave
typically remain constan as a sound wave propagates.
- 52. What determines the period of an ultrasound wave?
A. the transducer
B. the medium through which the sound travels
C. both A and B
D. neither choice A nor B - -A. The sound source (the transdlcor) that
produces an acoustic signal deemines the period of a wave. The wave's priod
is unrelated to the medium througn which the sound travels, and will not
change as the wave moves from one medium to another.
- 49. A pair of waves are in phase. What occurs
A. reflection
B. constructive interference
C. refraction
D. destructive interference - -B. Waves that are in phase constructively
interfere with each other. The that results from the combination single wave
of the two have a higher in-phase waves will always amplitude than either of
the original waves.
- 24. As sound travels through a medium, what term describes the effects of
the medium on the sound wave?
A. toxic effects
B. acoustic propagation properties
C. bioeffects
,D. transmission properties - -B. Acoustic propagation properties describe the
effects of the medium on the wave traveling through it. Acoustic means
"sound." Propagation means "to travel"
- 25. Which of the following is true of all waves?
A. they travel through a medium
B. all carry energy from one site to another
C. their amplitudes do not change
D. they travel in a straight line - -B. Waves carry energy from one place to
another. A is incorrect because some waves, such as light, can travel
through a vacuum. C is incorrect because many waves get weaker as they
travel. Certain waves do not travel in a straight line, so D is also incorrect.
- 26. Which of the following types of waves do not require a medium in order
to propagate? (More than one answer may be correct.)
A. light
B. heat
C. sound
D. television - -A, B, and D. Sound cannot travel through a vacuim; it
requires a medium in order to propate. Other waveforms such as light, hea
and TV waves are capable of traveling through a vacuum.
- 27. Which of the following describes the characteristics of a sound wave?
A. longitudinal, non-mechanical
B. mechanical, transverse
C. transverse, acoustic
D. mechanical, longitudinal - -D. Sound is a mechanical, longitudinal wave. A
mechanical wave, such as sound, actually imparts energy to the molecules of
the medium through which it travels. The molecules of the medium vibrate,
striking their neighbors, which in turn vibrate. This chain reaction results in
the acoustic energy traveling through the medium.
- 28. Sound is best described as ______
A. a series of compressions and rarefactions
B. a transverse wave
C. a wave that humans can hear
D. an oblique displacement of acoustic energy - -A. Sound is composed of a
series of Molecules in the compressions and rarefactions. medium are
alternately together (compressed) and stretched apart squeezed (rarefied).
- 29. All of the following are true about sound waves except ______
A. they are mechanical
B. they are transverse
C. they carry energy from place to place
D. they generally travel in a straight line - -B. Sound waves are not
transverse, they are longitudinal.
, - Which of the following 8 selections are acoustic variables? (True or False)
30. Frequency 31. Pressure 32. Propagation speed 33. Wavelength 34.
Voltage 35. Intensity 36. Motion of particles in the wave 37. Density - -False.
True. False. False. False. False. True. True. Acoustic variables identify certain
wave as sound waves. These quantities are pressure, density and particle
motion.
- 38. What are the units of a pressure measurement of an acoustic wave?
(More than one answer may be correct.)
A. atmospheres (atm)
B. pascals (Pa)
C. millimeters of mercury (mm Hg)
D. pounds sq. inch (Ibin?) - -A, B, C, and D. All of these terms are appropriate
to represent pressure (just as weight can be reported with units of pounds,
ounces, tons, or grams). However, the pressure of sound waves is most often
reported in units of pascals.
- 39. Sound can be characterized as:
A. energy flowing through a vacuum
B. a variable
C. cyclical oscillations in certain variables
D. a principle of acoustics - -C. Sound is a wave. A wave is the rhythmical
variation throughout time.
- 41. A longitudinal wave propagates from east to west at a speed of 2 miles
per hour. What is the direction of motion of the particles within the wave?
A. from east to west only
B. alternately from east to west and then from west to east
C. from north to south only
D. alternately from south to north and then from north to south - -B. A
longitudinal wave is defined as a wave whose particles vibrate back and forth
in the same direction that the wave is propagating. Since the wave is
traveling from east to west, the particles in this wave will move alternately
from east to west and then from west to east.
- 45. The direction of motion of a particle in a wave is perpendicular to the
direction of propagation of the wave. What type of wave is this?
A. longitudinal
B. acoustic
C. mechanical
D. transverse - -D. A characteristic of transverse waves is that the direction
of propagation is perpendicular to the direction of particle motion in the
wave. Sound waves are not transverse, but rather longitudinal.
, - 46. A particle within a transverse wave is traveling vertically. What is the
direction of the wave's propagation?
A. horizontal
B. vertical
C. diagonal; both horizontal and vertical
D. cannot be determined - -A. The particles within a transverse wave travel
in a direction that is perpendicular to the direction of propagation of the
wave. If a transverse wave is traveling vertically, the particles in the wave
are traveling horizontally. A water wave is a primarily a transverse wave. The
wave propagates sideways along the surface of the water, while a ball
floating on top of the water moves up and down as the wave passes.
- 47. Waves that exist at the same location and time will combine. What is
this called?
A. inference
B. rarefaction
C. interference
D. longitudinal interaction - -C. The combination of many waves into a single
wave is called interference.
- 53. Which of the following units are appropriate to describe the period of
an acoustic wave? (More than one answer may be correct.)
A. minutes
B. microseconds
C. meters
D. mm/us E. cubic centimeters - -A and B. The period of a wave is defined as
the time that elapses as a wave oscillates through a single cycle. The units
for period must be a measure of time, such as minutes or seconds. A and B
are units of time. The incorrect selections C, D, and E are units of distance,
speed, and volume, respectively.
- 54. True or False? The sonographer has the ability to alter the period of an
ultrasound wave that is produced by a basic transducer. - -False. The
sonographer cannot adjust the period (or frequency) of a wave produced by
a basic transducer. Think of striking a key on a piano. The frequency of
sound created by striking a single key is constant. If the sound beam's
frequency and period are not suited for the particular type of imaging, the
sonographer must select a new transducer with a different frequency.
- 55. What term describes the number of cycles that an acoustic variable
completes in a second?
A. period
B. frequency
C. pulse repetition period
Review Questions & Answers
50. What is the range of periods commonly found in waves produced by
ultrasound systems?
A. 0.001 to 1s
B. 0.06 to 0.5 us
C. 0.2 to 1 ms
D. 10 to 100 ns - -B. Ultrasonic imaging waves have a period in ps. The
period is the range of 0.06 to 0.5 the time of a single cycle. Period is the
loolto reciprocal of frequency. A wave with a frequency of 2 MHz has a period
of 0.5 usec. A wave with a frequency of 15 MHz has a period of 0.06 us.
- 51. With standard ultrasonic imaging, what happens to the period of a
wave as it propagates?
A. increases
B. decreases
C. remains the same - -C. Certain parameters of a wave change as the wave
travels through the body. However, the period and the frquency of a wave
typically remain constan as a sound wave propagates.
- 52. What determines the period of an ultrasound wave?
A. the transducer
B. the medium through which the sound travels
C. both A and B
D. neither choice A nor B - -A. The sound source (the transdlcor) that
produces an acoustic signal deemines the period of a wave. The wave's priod
is unrelated to the medium througn which the sound travels, and will not
change as the wave moves from one medium to another.
- 49. A pair of waves are in phase. What occurs
A. reflection
B. constructive interference
C. refraction
D. destructive interference - -B. Waves that are in phase constructively
interfere with each other. The that results from the combination single wave
of the two have a higher in-phase waves will always amplitude than either of
the original waves.
- 24. As sound travels through a medium, what term describes the effects of
the medium on the sound wave?
A. toxic effects
B. acoustic propagation properties
C. bioeffects
,D. transmission properties - -B. Acoustic propagation properties describe the
effects of the medium on the wave traveling through it. Acoustic means
"sound." Propagation means "to travel"
- 25. Which of the following is true of all waves?
A. they travel through a medium
B. all carry energy from one site to another
C. their amplitudes do not change
D. they travel in a straight line - -B. Waves carry energy from one place to
another. A is incorrect because some waves, such as light, can travel
through a vacuum. C is incorrect because many waves get weaker as they
travel. Certain waves do not travel in a straight line, so D is also incorrect.
- 26. Which of the following types of waves do not require a medium in order
to propagate? (More than one answer may be correct.)
A. light
B. heat
C. sound
D. television - -A, B, and D. Sound cannot travel through a vacuim; it
requires a medium in order to propate. Other waveforms such as light, hea
and TV waves are capable of traveling through a vacuum.
- 27. Which of the following describes the characteristics of a sound wave?
A. longitudinal, non-mechanical
B. mechanical, transverse
C. transverse, acoustic
D. mechanical, longitudinal - -D. Sound is a mechanical, longitudinal wave. A
mechanical wave, such as sound, actually imparts energy to the molecules of
the medium through which it travels. The molecules of the medium vibrate,
striking their neighbors, which in turn vibrate. This chain reaction results in
the acoustic energy traveling through the medium.
- 28. Sound is best described as ______
A. a series of compressions and rarefactions
B. a transverse wave
C. a wave that humans can hear
D. an oblique displacement of acoustic energy - -A. Sound is composed of a
series of Molecules in the compressions and rarefactions. medium are
alternately together (compressed) and stretched apart squeezed (rarefied).
- 29. All of the following are true about sound waves except ______
A. they are mechanical
B. they are transverse
C. they carry energy from place to place
D. they generally travel in a straight line - -B. Sound waves are not
transverse, they are longitudinal.
, - Which of the following 8 selections are acoustic variables? (True or False)
30. Frequency 31. Pressure 32. Propagation speed 33. Wavelength 34.
Voltage 35. Intensity 36. Motion of particles in the wave 37. Density - -False.
True. False. False. False. False. True. True. Acoustic variables identify certain
wave as sound waves. These quantities are pressure, density and particle
motion.
- 38. What are the units of a pressure measurement of an acoustic wave?
(More than one answer may be correct.)
A. atmospheres (atm)
B. pascals (Pa)
C. millimeters of mercury (mm Hg)
D. pounds sq. inch (Ibin?) - -A, B, C, and D. All of these terms are appropriate
to represent pressure (just as weight can be reported with units of pounds,
ounces, tons, or grams). However, the pressure of sound waves is most often
reported in units of pascals.
- 39. Sound can be characterized as:
A. energy flowing through a vacuum
B. a variable
C. cyclical oscillations in certain variables
D. a principle of acoustics - -C. Sound is a wave. A wave is the rhythmical
variation throughout time.
- 41. A longitudinal wave propagates from east to west at a speed of 2 miles
per hour. What is the direction of motion of the particles within the wave?
A. from east to west only
B. alternately from east to west and then from west to east
C. from north to south only
D. alternately from south to north and then from north to south - -B. A
longitudinal wave is defined as a wave whose particles vibrate back and forth
in the same direction that the wave is propagating. Since the wave is
traveling from east to west, the particles in this wave will move alternately
from east to west and then from west to east.
- 45. The direction of motion of a particle in a wave is perpendicular to the
direction of propagation of the wave. What type of wave is this?
A. longitudinal
B. acoustic
C. mechanical
D. transverse - -D. A characteristic of transverse waves is that the direction
of propagation is perpendicular to the direction of particle motion in the
wave. Sound waves are not transverse, but rather longitudinal.
, - 46. A particle within a transverse wave is traveling vertically. What is the
direction of the wave's propagation?
A. horizontal
B. vertical
C. diagonal; both horizontal and vertical
D. cannot be determined - -A. The particles within a transverse wave travel
in a direction that is perpendicular to the direction of propagation of the
wave. If a transverse wave is traveling vertically, the particles in the wave
are traveling horizontally. A water wave is a primarily a transverse wave. The
wave propagates sideways along the surface of the water, while a ball
floating on top of the water moves up and down as the wave passes.
- 47. Waves that exist at the same location and time will combine. What is
this called?
A. inference
B. rarefaction
C. interference
D. longitudinal interaction - -C. The combination of many waves into a single
wave is called interference.
- 53. Which of the following units are appropriate to describe the period of
an acoustic wave? (More than one answer may be correct.)
A. minutes
B. microseconds
C. meters
D. mm/us E. cubic centimeters - -A and B. The period of a wave is defined as
the time that elapses as a wave oscillates through a single cycle. The units
for period must be a measure of time, such as minutes or seconds. A and B
are units of time. The incorrect selections C, D, and E are units of distance,
speed, and volume, respectively.
- 54. True or False? The sonographer has the ability to alter the period of an
ultrasound wave that is produced by a basic transducer. - -False. The
sonographer cannot adjust the period (or frequency) of a wave produced by
a basic transducer. Think of striking a key on a piano. The frequency of
sound created by striking a single key is constant. If the sound beam's
frequency and period are not suited for the particular type of imaging, the
sonographer must select a new transducer with a different frequency.
- 55. What term describes the number of cycles that an acoustic variable
completes in a second?
A. period
B. frequency
C. pulse repetition period
