# Chapter 2 Flashcards Preview

## SON111AB-Physics > Chapter 2 > Flashcards

Flashcards in Chapter 2 Deck (70)
1
Q

Aborption

A

conversion of sound to heat

2
Q

Acoustic

A

having to do with sound

3
Q

Acoustic variables

A

pressure, density, and particle vibration; sound wave quantities that vary in space and time

4
Q

Amplitude

A

maximum variation of an acoustic variable or voltage

5
Q

Attenuation

A

decrease in amplitude and intensity with distance as a wave travels through a medium

6
Q

Attenuation coefficient

A

attenuation per centimeter of wave travel

7
Q

Backscatter

A

sound scattered back in the direction from which it originally came

8
Q

Bandwidth

A

range of frequencies contained in an ultrasound pulse; range of frequencies within which a material, device, or system can operate

9
Q

Compression

A

reduction in differences between small and large amplitudes. Region of high density and pressure in a compressional wave

10
Q

Constructive interference

A

combination of positive or negative pressures

11
Q

Continuous Wave

A

a wave in which cycles repeat indefinitely; not pulsed, abbreviate CW

12
Q

Contrast agent

A

a suspension of bubbles or particles introduced into circulation to enhance the contrast between anatomic structures; thereby improving their imaging

13
Q

coupling medium

A

a gel used to provide a good sound path between a transducer and the skin by eliminating the air between the two

14
Q

cycle

A

one complete variation of an acoustic variable

15
Q

decibel

A

unit of power or intensity ratio; the number of decibels is 10 times the logarithm (to the base 10) of the power or intensity ratio. Abbreviated dB

16
Q

Density

A

mass divided by volume

17
Q

destructive interference

A

combination of positive and negative pressures

18
Q

duty factor

A

fraction of time that pulsed ultrasound is on

19
Q

echo

A

reflection

20
Q

energy

A

capability of doing work

21
Q

fractional bandwidth

A

bandwidth divided by operating frequency

22
Q

frequency

A

number of cycles per second

23
Q

fundamental frequency

A

the primary frequency in a collection of frequencies that can include odd and even harmonic and subharmonics

24
Q

harmonics

A

frequencies that are even and odd multiples of another, commonly called fundamental or operating frequency

25
Q

Hertz

A

unit of frequency, one cycle per second; unit of pulse repetition frequency; one pulse per second. abbreviated Hz

26
Q

impedance

A

density multiplied by the sound propagation speed

27
Q

incidence angle

A

angle between incident sound direction and a line perpendicular to the boundary of a medium

28
Q

intensity

A

power divided by area

29
Q

intensity reflection coefficient

A

reflected intensity divided by incident intensity; the fraction of incident intensity reflected

30
Q

intensity transmission coefficient

A

transmitted intensity divided by incident intensity; the fraction of incident intensity transmitted into the second medium

31
Q

interference

A

combinations of positive and/or negative pressures

32
Q

Kilohertz

A

one thousand hertz. abbreviated kHz

33
Q

longitudinal wave

A

wave in which the particles motion is parallel to the direction of wave travel (compressional wave)

34
Q

medium

A

material through which a wave travels

35
Q

Megahertz

A

one million hertz. MHz

36
Q

nonlinear propagation

A

sound propagation in which the propagation speed depends on pressure causing the wave shape to change and harmonics to be generated

37
Q

oblique incidence

A

sound direction that is not perpendicular to media boundaries

38
Q

penetration

A

imaging depth

39
Q

period

A

time per cycle

40
Q

perpendicular

A

geometrically related by 90 degrees

41
Q

perpendicular incidence

A

sound direction that is perpendicular to the boundary between media

42
Q

power

A

rate at which work is done; rate at which energy is transferred

43
Q

pressure

A

force divided by the area in a fluid

44
Q

propagation

A

progression or travel

45
Q

propagation speed

A

speed at which a wave moves through a medium

46
Q

pulse

A

a brief excursion of a quantity from its normal value; a few cycles

47
Q

pulse duration

A

interval of time from beginning to end of a pulse

48
Q

pulse-repetition frequency

A

number of pulsed per second; sometimes called pulse repetition rate. abberviated PRF

49
Q

pulse-repetition period

A

interval of time from the beginning of one pulse to the beginning of the next

50
Q

pulsed ultrasound

A

ultrasound produced in pulsed form by applying electric pulses or voltages of one or few cycles to the transducer

51
Q

range equation

A

relationship between round-trip pulse travel time, propagation speed, and distance to a reflector

52
Q

rarefraction

A

region of low density and pressure in a compressional wave

53
Q

Rayl

A

unit of impedance

54
Q

reflection

A

portion of sound returned from a media boundary; echo

55
Q

reflection angle

A

angle between the reflected sound direction and a line perpendicular to the media boundary

56
Q

reflector

A

media boundary that produces a reflection; reflecting surface

57
Q

refraction

A

change of sound direction on passing from one medium to another

58
Q

scatter

A

an object that scatters sound in many directions because of its small size or its surface roughness.

59
Q

scattering

A

diffusion or redirection of sound in several directions upon encountering a particle suspension or a rough surface

60
Q

sound

A

traveling wave of acoustic variables

61
Q

spatial pulse length

A

length of space over which a pulse occurs

62
Q

speckle

A

the granular appearance of images and spectral displays that is caused by the interference of echoes from the distribution of scatterers in tissue

63
Q

specular reflection

A

reflection from a large (relative to wavelength), flat, smooth boundary

64
Q

stiffness

A

property of a medium; applied pressure divided by the fractional volume change produced by the pressure

65
Q

strength

A

nonspecific term referring to amplitude or intensity

66
Q

transmission angle

A

angle between the transmitted sound direction and a line perpendicular to the media boundary

67
Q

transverse wave

A

a sound wave in which the particle motion is perpendicular to the direction of wave travel

68
Q

ultrasound

A

soung having a frequency greater than what humans can hear, that is greater than 20 kHz

69
Q

wave

A

traveling variation of one or more quantities

70
Q

wavelength

A

length of space over which a cycle occurs