Ch. 1-4 Physics Test Flashcards

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1
Q

Concentrations of energy in a sound beam

A

intensity

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2
Q

Intensity units are

A

watts/squared

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3
Q

Intensity is determined by the

A

sound source

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4
Q

Relationship between intensity and power

A

directly proportional

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5
Q

If the amplitude is doubled, the intensity is increased by a factor of

A

4

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6
Q

If the amplitude is halved, the intensity is reduced by a factor of

A

1/4

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7
Q

Length or distance of a single cycle

A

wavelength

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8
Q

Wavelength units

A

length

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9
Q

Wavelength determined by

A

both medium and sound source

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10
Q

Wavelength equation

A

wavelength (mm)= (1.54mm/microsec)/(MHz)

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11
Q

In soft tissue, sound with a frequency of 1 MHz has a wavelength of

A

1.54mm

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12
Q

rate that sound travels through a medium

A

propagation speed

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13
Q

Propagation speed is also called

A

speed or velocity

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14
Q

Speed units

A

distance over time (m/sec)

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15
Q

Speed determined by

A

medium

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16
Q

General Rule: ____

A

gases, liquids, solids

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17
Q

Put the following in order from fastest to slowest: fat, lung, air, soft tissue, bone, tendon

A

bone, tendon, soft tissue, fat, lung, air

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18
Q

Related to weight

A

Density

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19
Q

Related to change in shape

A

stiffness

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20
Q

When stiffness increases, speed

A

increases

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21
Q

When stiffness decreases, speed

A

decreases

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22
Q

When density increases, speed

A

decreases

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23
Q

When density decreases, speed

A

increases

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24
Q

In-phase waves interfere

A

constructive waves

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25
Q

Out-of phase waves interfere

A

deconstructive waves

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26
Q

A wave with a frequency of 15,000 MHz is ultrasonic. T/F

A

true

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27
Q

If the power of a wave is halved, the intensity is reduced to one-fourth its original value. T/F

A

false

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28
Q

The sonographer adjusts the output of the ultrasound system by increasing the amplitude by a factor of 3. What happens to the intensity

A

increased by a factor of 9

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29
Q

Collection of cycles that travel together

A

pulse

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30
Q

five parameters of pulsed ultrasound are

A

pulse duration, spatial pulse length, pulse repetition period, pulse repetition frequency, duty factor

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31
Q

time from the start of a pulse to the end of that SAME pulse

A

pulse duration

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32
Q

pulse duration is the

A

units of time that the pulse is ON

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33
Q

pulse duration is determined by the

A

sound source

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34
Q

time from the start of one pulse to the start of the NEXT pulse

A

pulse repetition period

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35
Q

PRP includes one

A

pulse duration time and one listening time

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36
Q

PRP is determined by the

A

sound source

37
Q

As imaging depth increases, PRP

A

increases

38
Q

As imaging depth decreases, PRP

A

decreases

39
Q

number of pulses that occur in one second

A

pulse repetition frequency

40
Q

PRF units

A

hertz

41
Q

PRF determined by the

A

sound source

42
Q

As imaging depth increases, PRF

A

decreases

43
Q

As imaging depth decreases, PRF

A

increases

44
Q

percentage or fraction of time that the system’s probe is transmitting sound waves

A

duty factor

45
Q

If the duty factor is 100% or 1.0, the the system is

A

ON (cw)

46
Q

If the duty factor is 0%, then the machine is

A

off

47
Q

CW sound can be used to make anatomical images. T/F

A

False

48
Q

length or distance that a pulse occupies in space

A

Spatial pulse length

49
Q

The distance from the start to the end of one pulse is

A

SPL

50
Q

SPL units

A

distance and length

51
Q

SPL determined by

A

both medium and sound source

52
Q

determines axial resolution

A

SPL

53
Q

SPL equation

A

SPL= # cycles x wavelength (mm)

54
Q

By adjusting imaging depth, the operator changes the

A

duty factor, PRF, PRP

55
Q

What two are characteristics of the pulse itself and are inherent in the design of the transducer system

A

pulse duration, SPL

56
Q

A 5MHz probe uses a cw with a prop speed of 1.8km/sec. The probe then uses pulsed wave with a duty factor of 0.5. What is the new prop speed

A

1.8km/sec

57
Q

How many hertz is 5MHz

A

5,000,000 hertz

58
Q

How much bigger is a billion than a million

A

1000 (10^3)

59
Q

If you have to divide an exponential number you will

A

subtract exponents

60
Q

If you have to multiply an exponential number you will

A

add the exponents

61
Q

Macro means

A

large

62
Q

Micro means

A

small

63
Q

Sound is comprised of

A

compressions and rarefactions

64
Q

Compressions are regions of ____ pressure and density

A

increased

65
Q

Rarefactions are regions of _____ pressure and density

A

decreased

66
Q

The 3 acoustic variables are

A

pressure, density and distance

67
Q

Time required to compete a single cycle

A

period

68
Q

period units

A

time

69
Q

period determined by

A

sound source

70
Q

number of certain events that occur in a particular time duration

A

frequency

71
Q

frequency units

A

hertz

72
Q

frequency determined by

A

sound source

73
Q

Can period be adjusted

A

no

74
Q

Can frequency be adjusted

A

no

75
Q

Period and frequency are

A

reciprocals, inversely related

76
Q

As frequency increases, period

A

decreases

77
Q

As frequency decreases, period

A

increases

78
Q

> 20,000Hz

A

ultrasound

79
Q

between 20Hz and 20,000Hz

A

audible sound

80
Q

<20Hz

A

infrasound

81
Q

Describes the strength of a sound beam

A

amplitude, power, intensity

82
Q

difference between the average value and the max value of an acoustic cariable

A

amplitude

83
Q

amplitude units are

A

pressure, density, distance

84
Q

amplitude is determined by the

A

sound source

85
Q

amplitude ____ as it travels through the body

A

decreases

86
Q

rate that work is performed, or the rate of energy transfer

A

power

87
Q

power units

A

watts

88
Q

power is determined by the

A

sound source

89
Q

power is proportional to the wave’s amplitude

A

squared