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Physics > Ch 1-4 8 > Flashcards

Ch 1-4 8 Flashcards

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0
Q

The molecules vibrate in the same direction as the sound travels. I.e, sound waves.

A

Longitudinal Wave

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1
Q

When one value increases, and so does the other value, the two values are said to be ___________.

A

Directly Proportional

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2
Q

The molecules vibrate at 90 degrees to the direction of energy travel. i.e. Water ripples

A

Transverse Wave

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3
Q

concentration of force

units: lb/sq inch, Pascals Pa

A

Pressure

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4
Q

concentration of mass or weight

units: kg/cubic cm

A

Density

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5
Q

measure of particle motion

units: cm, feet, miles

A

Distance

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6
Q

The distance of one wave cycle.

A

Wavelength

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7
Q

•The length of time it takes to complete one single cycle of sound or to one complete single wavelength.

Units: seconds, msec, hours – all units of time
=1/frequency

A

Period

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8
Q

The # of wave cycles per second.

1 cycle per second = 1 hertz Hz

A

Frequency

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9
Q

The speed at which wave cycles travel.

A

Propagation Speed

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10
Q

(Sin Angle of Incidence)/(Sin Angle of Refraction)= c1/c2

Where c1 & c2 are the speeds of sound in the two mediums

A

Snell’s Law

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11
Q 
Z=P/V
Where P = excess pressure and
V=the particle velocity.          OR
Z=P x c
Where c=speed of light
A

Acoustic Impedance

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12
Q

The dominant factor in attenuation (80%).

-conversion of sound to heat

A

Absorption

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13
Q

Occurs at a boundary between 2 different media with different impedances.
-the sound bounces back (toward transducer)

A

Reflection

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14
Q

z=P x V , measured in Rayls. (z=Density x Prop Speed)

A

Impedance

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15
Q

Smooth surface that causes sound to bounce back toward the transducer.

A

Specular Reflector

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16
Q

Scatter returning in the same general direction as the transducer.

A

BackScatter

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17
Q

Interface has irregularities one wavelength or smaller.

A

Non-specular scattering.

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18
Q

Sound scatters symmetrically in all directions. Not related to incidence angle. Increase frequency, and increase this.

A

Rayleigh scattering.

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19
Q

%R=Reflected Intesity/Incidence Intensity=((z2-z1)/(z2+z1))^2

A

Intensity Reflection Coefficient

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20
Q

90 degrees. (Porn)

A

Normal Incidence

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21
Q

not 90 degrees

A

Oblique Incidence

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22
Q

a bending from a straight line or path or a change in direction of a wave travelling from one medium to another. Must have two things: an Oblique Incidence, and2 media with different propagation speeds. Related to the change in acoustic velocity. (If medium 2 is faster, then it will increase the transmit angle.

A

Refraction

23
Q

Sin (angle of transmit)/ sin (angle of incidence)=prop speed 2/prop speed 1

A

Snell’s Law

24
Q

“bulk modulus.” The extent to which a material cannot be compressed. To increase this will increase propagation speed.

A

Stiffness

25
Q

aka Harmonics

A

Non-linear Propagation

26
Q

Pulse, then listen for echo

A

Puled Ultrasound

27
Q

Time from the start of one pulse to the end of the same pulse. THis can only be changed by changing the transducer.

A

Pulse Duration

28
Q

% of the time that the system is transmitting a pulse and not “listening.” Determined by the sound source.

A

Duty Factor

29
Q

of pulses that occur in a single second(Hz/sec). Determined by the sound source.

A

Pulse Repetition Frequency (PRF)

30
Q

Time from the start of a pulse to the start of the next pulse (includes “listening time”).

Determined by the sound source. CAN be changed by the sonographer by changing the listening time.
= 1/PRF

A

Pulse Repetition Period (PRP)

31
Q

The distance a pullse occupies in space. # of cycles in a pulse x wavelength. Determined by the sound source and the medium. Cannot be changed by the sonographer.
Increase freq, Increase this

A

Spatial Pulse Length

32
Q

Weakening of a sound wave as it travels through media. Decrease in amplitude and decrease in intensity. Increase frequency and increase this

A

Attenuation

33
Q

+3 Db doubles the sound

+10 dB ten times the sound

A

Decibels

34
Q

value that expresses how different materials attenuate the sound beam per unit length (dB/cm). The average attenuation coefficient in soft tissue is 1/2 the transducer frequency.

A

Attenuation Coefficient

35
Q

The distance the sound beam travls when its intensity is reduced to 1/2 its original value.

A

Half-Value Layer

36
Q

The fraction of the original intensity after attenuation.

A

Intensity Ratio

37
Q

a peak aligns with a peak; increase in amplitude

A

Constructive Interference

38
Q

a peak aligns with a trough; decrease in amplitude

A

Destructive Interference

39
Q

Distance to Boundary = (go-return time x speed)/2

d=ct/2

A

Range Equation

40
Q

Every 13 microseconds of go-return time means the reflector is 1 cm deeper in the body

A

13 microsecond rule

41
Q

when wave peaks and troughs continue to line up.

A

In-Phase Wave

42
Q

When troughs from one wave continually line up with the peaks from another wave.

A

Out-of-Phase Wave

43
Q

The strength of the sound beam, maximum variation from the baseline (dB)

A

Amplitude

44
Q

The rate that work is performed, rate of energy transfer in the entire beam. Measured in watts.
P=I x CS
P is proportional to Amplitude squared

A

Power

45
Q

Concentration of energy in certain areas of the sound beam

I=P/CS (watts/cm^2)

A

Intensity

46
Q

The highest intensity area or time of the sound beam

A

Peak

47
Q

(Peak + low + medium)/3

A

Average Intensity

48
Q

Greatest at the center and in focal zone of the sound beam

A

Spatial Intensities

49
Q

Occurs with Time

A

Temporal non-uniformity

50
Q

Is greatest at the center of the beam

A

Spatial non-uniformity

51
Q

Related or proportional

A

Related, Proportional, Directly Proportional

52
Q

As one value increases, the other value decreases.

A

Inversely proportional.

53
Q

The effects that are made on the human body

A

Biological Effects

54
Q

The thing that is creating the sound wave

A

Source

55
Q

The material that the sound wave is traveling through

A

medium

Physics (4 decks)

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