1.
A wave is a traveling variation in quantities called?
Correct Answer
Wave Variables
2.
Sound is a traveling variation in quantities called?
Correct Answer
Acoustic Variables
3.
Ultrasound is a sound with a frequency greater than ________Hz
Correct Answer
20,000
4.
Acoustic Variables include __________, __________, and __________ _________*3 Variables*
Correct Answer(s)
B. Pressure
C. Density
D. Particle Vibration
Explanation
A Wave is a Traveling Variation
5.
Which of the following frequencies are in the Ultrasound Range?
Correct Answer(s)
C. 15 MHz
D. 30,000Hz
E. 0.04 MHz
6.
Which of the following are Acoustic Variables? ***More than one correct answer***
Correct Answer(s)
A. Pressure
D. Particle Motion
7.
Frequency is a measure of how many ______ an acoustic variable goes through in a second.
Correct Answer(s)
Cycles
Explanation
Frequency is reported in units of per second , 1/Sec, Hertz, or Hz. Hertz is another way to say "Per Second"
8.
The unit of frequency is ______, which is abbreviated________
Correct Answer(s)
Hertz, Hz
9.
Period is the ______ that it takes for one cycle to occur.
Correct Answer(s)
Time
Explanation
Time from the start of a cycle to the start of the next cycle *Period is determined by the Sound Source ONLY, not by the medium
10.
Period decreases as ____________ increases.
Correct Answer(s)
Frequency
Explanation
Period and frequency are INVERSELY RELATED to each other
11.
Wavelength is the length of ______ over which one cycle occurs
Correct Answer(s)
Space
Explanation
Wavelength is the distance that a single cycle occupies space
12.
Propagation Speed is the speed with which a ________ moves through a medium in 1 second.
Correct Answer(s)
Wave
Cycle
Wave or Cycle
Sound Wave
13.
Wavelength is equal to _________ ________ divided by _________
Correct Answer(s)
Propagation Speed, Frequency
Explanation
The relationship between the three is that wavelength is equal to Propagation speed (1,540 m/s or 1.54mm/us) divided by frequency. **This equation predicts that wavelength decreases as frequency increases **Page 19 & 20 in Kremkau**
14.
The _________ and_________ of a medium determine Propagation Speed
Correct Answer(s)
Density, Stiffness
Stiffness, Density
Explanation
Stiffness (Hardness)is the resistance of a material to compression *Page 20 Kremkau*
15.
Propagation Speed Increases if ____________ is Increased.
Correct Answer(s)
Stiffness
Hardness
Stiffness or Hardness
Hardness or Stiffness
Explanation
Page 22 Kremkau
16.
The average Propagation Speed in soft tissues is ?
Correct Answer(s)
A. 1,540 m/s
D. 1.54 mm/us
17.
Propagation Speed is determined by
Correct Answer
E. Medium
Explanation
Speed is determined only by the medium through which the sound is traveling **Propagation Speed is the speed of sound through a medium**
18.
The wavelength of 7-MHz ultrasound in soft tissue is __________mm
Correct Answer
0.22
Explanation
***Wavelength ( __ ) = Speed (1.54mm/us) / Frequency (7-Mhz)
* 1.54 mm/us DIVIDED by 7Mhz = 0.22mm
19.
Wavelength in Soft Tissue _________ as Frequency Increases
Correct Answer
Decreases
Explanation
***If Frequency INCREASES ***Wave Length DECREASES
***If Frequency DECREASES *** Wave Length INCREASES
20.
It takes ________us for ultrasound to travel 1.54cm in Soft Tissue
Correct Answer
10
Explanation
t = d / s
Speed of sound = 1.54 mm/us
Distance = 1.54cm **Convert to mm** 15mm
21.
Propagation Speed in Bone is ______ than in Soft Tissue.
Correct Answer
Higher
22.
Sound travels fastest in?
Correct Answer
D. Steel
Explanation
Fastest in SOLIDS
23.
Solids have higher propagation speeds than liquids because they have greater
Correct Answer
B. Stiffness
24.
Sounds travels slowest in?
Correct Answer
A. Gases
25.
Sound is a _____________wave
*More than 1 correct answer*
Correct Answer(s)
A. Mechanical
B. Longitudinal
C. Compressional
26.
If Frequency in Soft Tissue is Doubled, Propagation Speed is _________....
Correct Answer(s)
Unchanged
Explanation
Propagation Speed is determined ONLY by the medium through which the sound is traveling.
Frequency of a sound wave is determined by the SOUND SOURCE only, not by the MEDIUM through which the sound is traveling
27.
If Wavelength is 2mm and the frequency is Doubled the Wavelength becomes__________mm
Correct Answer(s)
1
Explanation
As long as a wave remains in one medium, wavelength and frequency are inversely related. As frequency increases, wavelength decreases. The lower the frequency, the longer the wavelength. **Example** If a wave's frequency is twice that of another, the wavelength will be HALF as much
*Edelman PG. 33*
28.
From given values for propagation speed and frequency, which of the following can be calculated?
Correct Answer
C. Wavelength
29.
If two media have different stiffness, the one with the higher stiffness will have the higher propagation speed.
Correct Answer
A. True
Explanation
Sound travels fastest in solids, slower in liquids, and slowest in gases