Physics Test #1 Chapter 2 Part 1

1. Period is the ______ that it takes for one cycle to occur.

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

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

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4. Wavelength in Soft Tissue _________ as Frequency Increases

***If Frequency INCREASES ***Wave Length DECREASES
***If Frequency DECREASES *** Wave Length INCREASES

Explanation

***If Frequency INCREASES ***Wave Length DECREASES
***If Frequency DECREASES *** Wave Length INCREASES

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5. It takes ________us for ultrasound to travel 1.54cm in Soft Tissue

t = d / s
Speed of sound = 1.54 mm/us
Distance = 1.54cm **Convert to mm** 15mm

Explanation

t = d / s
Speed of sound = 1.54 mm/us
Distance = 1.54cm **Convert to mm** 15mm

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7. Frequency is a measure of how many ______ an acoustic variable goes through in a second.

Frequency is reported in units of per second , 1/Sec, Hertz, or Hz. Hertz is another way to say "Per Second"

Explanation

Frequency is reported in units of per second , 1/Sec, Hertz, or Hz. Hertz is another way to say "Per Second"

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8. The wavelength of 7-MHz ultrasound in soft tissue is __________mm

***Wavelength ( __ ) = Speed (1.54mm/us) / Frequency (7-Mhz)

* 1.54 mm/us DIVIDED by 7Mhz = 0.22mm

Explanation

***Wavelength ( __ ) = Speed (1.54mm/us) / Frequency (7-Mhz)

* 1.54 mm/us DIVIDED by 7Mhz = 0.22mm

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9. If Wavelength is 2mm and the frequency is Doubled the Wavelength becomes__________mm

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*

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*

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11. If two media have different stiffness, the one with the higher stiffness will have the higher propagation speed.

True

False

Sound travels fastest in solids, slower in liquids, and slowest in gases

Explanation

Sound travels fastest in solids, slower in liquids, and slowest in gases

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15. Wavelength is equal to _________ ________ divided by _________

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**

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**

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16. If Frequency in Soft Tissue is Doubled, Propagation Speed is _________....

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

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

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17. Acoustic Variables include __________, __________, and __________ _________
*3 Variables*

Wave

Pressure

Density

Particle Vibration

A Wave is a Traveling Variation

Explanation

A Wave is a Traveling Variation

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18. Propagation Speed is determined by

Frequency

Amplitude

Wavelength

Period

Medium

Speed is determined only by the medium through which the sound is traveling **Propagation Speed is the speed of sound through a 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**

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21. Sounds travels slowest in?

Gases

Steel

22. Solids have higher propagation speeds than liquids because they have greater

Density

Stiffness

23. The _________ and_________ of a medium determine Propagation Speed

Stiffness (Hardness)is the resistance of a material to compression *Page 20 Kremkau*

Explanation

Stiffness (Hardness)is the resistance of a material to compression *Page 20 Kremkau*

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24. Sound travels fastest in?

Air

Helium

Water

Steel

A Vacuum

Fastest in SOLIDS

Explanation

Fastest in SOLIDS

25. From given values for propagation speed and frequency, which of the following can be calculated?

Amplitude

Impedance

Wavelength

Amplitude and Impedance

Impedance and Wavelength

26. Which of the following are Acoustic Variables?
***More than one correct answer***

Pressure

Frequecy

Propagation Speed

Particle Motion

Period

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27. The average Propagation Speed in soft tissues is ?

1,540 m/s

1,540 mm/us

1.54 m/s

1.54 mm/us

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28. Sound is a _____________wave
*More than 1 correct answer*

Mechanical

Longitudinal

Compressional

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29. Which of the following frequencies are in the Ultrasound Range?

15 Hz

15,000 Hz

15 MHz

30,000Hz

0.04 MHz

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