Physics- PW & CW w/Exam
sound
"Mechanical energy transmitted by pressure waves in a material medium." can best be defined as:
1.54
1.54 mm/ us = [answer] km/s
4
24 cm/min. = [answer] mm/sec
5 us
Five cycles of 1 MHz ultrasound are emitted per pulse with a pulse repetition frequency of 1000 pulses per second. What is the pulse duration?
1000 us
Five cycles of 1 MHz ultrasound are emitted per pulse with a pulse repetition frequency of 1000 pulses per second. What is the pulse repetition period?
2.5 us
Five cycles of 2 MHz ultrasound are emitted per pulse. What is the approximate pulse duration?
Fd*c/2*V*Ft the original equation solves for Doppler shift
Given the equation: Fd = 2 V Ft Cos < / cSolve for: Cos < = [answer]
directly
Hours worked and take-home pay are [answer] related.
inversely
How are hours of sleep and drowsiness related?
5,000 Hz
How many Hertz is 5 kHz?
6.9*10^-4
How many days are in a minute? (Hint: This should be a small value!) (Do on paper)
increase 16 times
If a wave's amplitude is quadrupled, the wave's intensity will [answer1] [answer2] times its original value.
stays the same
If all other factors remain the same, what happens to the duty factor as the ultrasound pulse travels from a medium with high sound speed to one with much lower speed?
increases
If all other factors remain the same, what happens to the duty factor when a transducer with longer pulse duration is used?
increases
If all other factors remain the same, what happens to the duty factor when the image depth is decreased from 8 cm to 5 cm?
0.5%
If pulse duration is 0.5 µs, and pulse repetition period is 100 µs, what is the duty factor?
decreases by 9 times
If the amplitude of a wave is decreased by 3 times, what happens to the wave intensity?
power is quartered
If the amplitude of a wave is halved, what happens to the wave power?
Stays the same
If the frequency of a wave increases, the propagation speed: (The medium does not change.)
increases by 3 times
If the power of a wave is increased by 3 times, what happens to the wave intensity?
0.4 us
In soft tissue, what is the approximate period of a 2.25 MHz ultrasound pulse
0.3%
What is the percent duty factor for a pulse echo beam having a 3 μs pulse duration and a 900 μs pulse repetition period?
1 year
What is the period of the earth's rotation around the sun?
0.3 mm
What is the wavelength of 5MHz in soft tissue?
0.61 mm
What is the wavelength of a 2.5 MHz ultrasound beam having a velocity of 1520 m/s in soft tissue?
energy
What is transferred from one location to another as a wave propagates?
1
When period and frequency are multiplied, the result is [answer].
constructive and destructive
When waves of different frequencies interact, which kind of interference results?
Pa
Which is an acceptable unit for pressure?
-distance -pressure -density
Which of the following are considered acoustic variables?
Longitudinal waves; requires a medium
Which of the following best describes sound waves?
Out of phase, will interfere destructively
Which of the following best describes wave A and C?
high density, low stiffness
Which of the following characteristics will produce the slowest speed of sound?
B
Which of the lines in the graph represent a direct relationship?
amplitude
Which parameter is a measure from the middle value to the maximum (or minimum) value of a wave?
period
Which parameter of a wave describes the amount of time it takes to complete one cycle?
1 kHz
Which pulse has a pulse repetition period of 1 ms?
wavelength
Which wave parameter describes the distance from the beginning to the end of one complete cycle?
frequency
Which wave parameter describes the number of cycles that pass a given point in one second?
peak
With regard to intensities, [answer] is always larger.
1.0
What is the duty factor of a continuous ultrasound beam?
50
5 W/cm 2 = [answer] mW/mm 2
500
50 cm = [answer] mm
7,500,000 Hz
7.5 MHz = [answer] Hz
0.68 mm
A 2.25 MHz three-cycle pulse of ultrasound is emitted at a pulse repetition frequency of 500 pulses per second. What is the approximate wavelength in soft tissue?
.067%
A 2.25 MHz, three-cycle pulse of ultrasound is emitted at a pulse repetition frequency of 500 pulses per second. What is the approximate percent duty factor?
0.2 us
A 4.5 MHz ultrasound beam will have a period of approximately:
milk
A 5 MHz ultrasound beam travels through a medium at a speed of 1500 m/s? This medium is most likely:
PRF= 1/500 us =.002/us
A 5 μs pulse is emitted every 500 μs. What is the pulse repetition frequency (PRF)?
= 1/ frequency =1/.002 = .5 ms
A 5 μs pulse is emitted every 500 μs. What is the pulse repetition period (PRP)?
1.54 mm/us
A parameter associated with a sound wave is the speed at which it travels through a given medium. What is the acoustic speed of ultrasound in soft tissue?
2 m/s
A sound beam has a wavelength of 2 mm and a period of 1.0 ms. What is the sound speed?
2 to 20 Mhz
Although up to 18 MHz can be used for superficial imaing, typical ranges for diagnostic imaging are [answer1] MHz to [answer2] MHz.
inverse
An example of a/an [answer] relationship is the link between caffeine and drowsiness.
not
An individual's hand size and their favorite car are [answer] related.
mm
Appropriate units of SPL are:
ms
Appropriate units of pulse duration are:
15 mm (d = 1.54mm/us * 10 us) =15.4 mm
Approximately how far will sound travel in soft tissue in 10 μs?
decreases
As "averaging (listening) time" increases, the corresponding average intensity
increase
As peak ultrasound intensity increases, the pulse-average and time-average intensities tend to
increases
As pulse duration is increased, spatial pulse length:
decreases
As ultrasound frequency is increased, pulse duration:
directly and directly
Power is [answer1] related to intensity and [answer2] related to amplitude.
High
Pressure in a compressed wave is [answer].
both on time and off time
Pulse Repetition Period is affected by
kilometer^2 feet^2
Select TWO examples of units for area
meter^3 yard^3
Select TWO examples of units for volume.
inches millimeters
Select TWO examples of units of length
density stiffness
Select the TWO characteristics of a medium that primarily determine its speed of sound.
image sharpness improves
Short pulses are better for ultrasound imaging because:
False
T/F: In a transverse wave, particles move in the same direction the wave propagates.
False
T/F: Sound can travel in a vacuum.
over the beam area
The beam uniformity coefficient involves the average intensity of the ultrasound beam
interference
The following sentence is best defined as:"More than one wave losing their individual characteristics and combining, at that moment, to form a single wave."
SPTP
The largest intensity measurement is:
power
The rate of energy transfer, or the rate at which work is performed is ____.
reciprocal
The relationship between PRP and PRF is best described as
SATA
The smallest intensity measurement is
intensity
The wave parameter that describes the concentration of energy in a sound beam is:
0.7 mm
The wavelength of a 2.25 MHz ultrasound beam in soft tissue is:
constructive
This set of waves will result in [answer] interference.
destructive
This set of waves will result in [answer] interference.
interference
Two waves are traveling in a medium and arrive at the same location at the same time. What event definitely takes place?
20,000 Hz
Ultrasound is defined as sound having a frequency above [answer] Hz.
2.05 mm
Using the derived answer for wavelength (.68 mm) in the previous question, what is the approximate spatial pulse length in soft tissue?
0.5%
Utilizing the values determined for PD and PRP, what is the duty factor of a system emitting a five-cycle, 1 MHz ultrasound pulse with a PRF of 1000 pulses per second, calculate the duty factor.
3.8 MHz
What is the approximate frequency of ultrasound that has a wavelength of 0.4 mm in soft tissue?
600 m/s
What is the approximate speed of sound if the wavelength is 0.2 mm and a 3 MHz ultrasound beam is used?
800 um
What is the approximate wavelength of 2 MHz in soft tissue?
100 to 1000 um
What is the approximate wavelength range for diagnostic ultrasound?
area
cm^2 is an appropriate unit of
