Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Basic Ultrasound Physics > Interaction of Sound and Media > Flashcards

Interaction of Sound and Media Flashcards

You may prefer our related Brainscape-certified flashcards:
Physics 101 flashcards AP® Physics flashcards
1
Q

Sound _______ as it propagates through the body

A

weakens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

The weakening of sound as it travels through tissues is called?

A

attenuation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

When sound waves are sent back to the system they are ______.

A

amplified

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is used to report a change in intensity?

A

decibels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

The log of 1000 is?

A

3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

The log of 100 is?

A

2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Decibal notation is?

A

a relative measurement, a comparison, a ratio, logarithmic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Decibels require _____ intensities

A

2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Positive decibels signify?

A

an increase or amplification

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

+3dB means the intensity _______.

A

doubles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

+10 dB means the intensity ________.

A

increases by ten times

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Negative decibels signify?

A

a decrease in intensity or attenution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

-3dB means the intensity _______

A

reduces to 1/2 its value

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

-10 dB means the intensity _______

A

reduces to 1/10 it’s original value

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

If the original intensity is 2 watts/cm2, and it reduces by 3 dB, what is the final intensity?

A

1 watt/cm2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

If the original intensity is 20 watts/cm2, and it reduces by 10 dB, what is the final intensity?

A

2 watts/cm2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Attenuation is determined by?

A

path length (depth) and frequency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Attenuation and path length are _______ related

A

directly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Attenuation and frequency are _________ related

A

directly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What three things contribute to attenuation?

A

reflection, scattering, absorption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Reflection occurs when a boundary is _____

A

large

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the two types of reflection?

A

specular and diffuse

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the two types of reflection?

A

specular and diffuse

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is specular reflection? When does it occur?

A

sound reflects in one direction; boundary is smooth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is diffuse reflection? When does it occur?

A

Sound is reflected in more than one direction; boundary is irregular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is scattering? When does it occur?

A

random redirection of sound in many directions; boundary is small

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Frequency and scattering are _______ related

A

directly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is an example of rayleigh scattering?

A

interaction with red blood cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is absorption?

A

Ultrasonic energy is converted into another energy form, like heat

30
Q

Absorption is _______ related to frequency

A

directly

31
Q

What does the attenuation coefficient represent?

A

the number of decibels of attenuation that occur when sound travels 1 cm

32
Q

Unit of the attenuation coefficient?

A

dB/cm

33
Q

Unit of attenuation?

A

dB

34
Q

Formula for total attenuation

A

attenuation coefficient x distance

35
Q

Attenuation coefficient and frequency are _______ related

A

directly

36
Q

The attenuation coefficient is _____ the frequency

A

half

37
Q

Define half value layer thickness

A

the distance sound travels to reduce the intensity to 1/2 it’s original value (-3dB)

38
Q

The HVL depends on?

A

medium and frequency

39
Q

Define impedance

A

the resistance to sound traveling in a medium

40
Q

What are the units of impedance

A

rayls (Z)

41
Q

What is the typical value of the HVL?

A

0.25-1.0 cm

42
Q

What can lead to a thin HVL?

A

high frequency sound or medium with high attenuation rate

43
Q

What can lead to a thick HVL?

A

low frequency sound or a media with a low attenuation rate

44
Q

Define incidence

A

the angle at which a wave strikes a bondary

45
Q

What are the three types of incident angles?

A

acute/oblique, right, obtuse/oblique

46
Q

Define normal incidence

A

beam strikes boundary at 90 degrees

47
Q

Normal incidence is also called?

A

perpendicular, orthoganal, right angle

48
Q

Define oblique incidence

A

Sound beam strikes boundary at angle other than 90 degrees

49
Q

What is the intensity before a wave strikes a boundary?

A

incident intensity

50
Q

What is the intensity of the portion of the wave that bounces back after striking a boundary?

A

reflected intensity

51
Q

What is the intensity of the portion of the wave after striking a boundary that continues forward?

A

Transmitted Intensity

52
Q

The Incident intensity equals?

A

Reflected intensity + Transmitted intensity

53
Q

What is the intensity reflection coefficient (IRC)?

A

the percentage of intensity that bounces back after striking a boundary

54
Q

What is the intensity transmission coefficient?

A

the percentage of intensity that continues forward after striking a boundary

55
Q

True or False: The IRC is usually larger than the ITC

A

False; ITC is larger (more transmission than reflection)

56
Q

IRC + ITC =?

A

100%

57
Q

Reflection only occurs when with normal incidence ?

A

When media have different impedances

58
Q

True or False: If impedances are identical with normal incidence there is reflection

A

False; All transmissio

59
Q

If there are slightly different impedances, there is a _______ amount of reflection

A

small

60
Q

If there are largely different impedances, there is a _______ amount of reflection

A

large

61
Q

With normal incidence, if two media have identical impedances, all sound is?

A

Transmitted

62
Q

With normal incidence, reflection and transmission depends on?

A

the impedences

63
Q

True or False: Reflection and transmission cannot be predicted with oblique incidence

A

True

64
Q

With oblique incidence, what two principles always apply?

A

conservation of energy; reflection angle = incident angle

65
Q

With an oblique incidence, the direction of the reflected echo is?

A

equal and opposite to the direction of the incidence

66
Q

What is refraction?

A

When a beam strikes a boundary at oblique incidence and transmits but changes direction (does not travel straight)

67
Q

Refraction only happens under what two conditions?

A

oblique incidence and different propagation speeds of two media

68
Q

True or False: Refraction can occur with normal incidence

A

False; only oblique incidence

69
Q

True or False: Refraction occurs when the speeds of two media are identical

A

False; different speeds

70
Q

When the speed of medium 2 is is greater than medium 1, the transmission angle will be ______ than the incident angle

A

greater

71
Q

When the speed of medium 2 is less than medium 1, the transmission angle will be______ than the incident angle

A

less

Basic Ultrasound Physics (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions