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CORE EXAM (quiz 1- physics) > physics paper txtbook > Flashcards

physics paper txtbook Flashcards

1
Q

3 acoustic variables (PDD)

A
  1. pressure
  2. density
  3. distance
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2
Q

sound waves are ___, ____, __ waves

A

acoustic, longitudinal, mechanical

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3
Q

7 acoustic parameters

A
  1. period
  2. frequency
  3. wavelength
  4. amplitude
  5. power
  6. intensity
  7. propagation speed
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4
Q

a pair of in phase waves that interfere result in the formation of a single wave of ___ (greater/ less) amplitude. Termed “___” interference

A

greater

constructive

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5
Q

the resultant wave value of ___ interference is smaller than one of it’s components

A

destructive

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6
Q

explain how both constructive and deconstructive interference can occur simultaneously

A

when waves of different frequencies interfere

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7
Q

time it takes a wave to complete a single cycle

A

period

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8
Q

t/f: the period is determined by the sound source only, not the medium

A

true

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9
Q

is period is adjustable by the sonographer ?

A

no

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10
Q

infrasound range

A

below 20Hz

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11
Q

audible frequency range

A

20Hz - 20KHz

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12
Q

ultrasound frequency range

A

ABOVE 20kHz (20, 000Hz)

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13
Q

what 2 things does frequency affect in sonography

A
  1. image quality

2. penetration

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14
Q

period and frequency are ___ related

A

inversely

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15
Q

increase in frequency = ___ in period

A

decrease

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16
Q

if the frequency is measured in Hz then the period will be measured in __

A

seconds

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17
Q

if the period is measured in milliseconds then the frequency is measured in ___

A

kHz

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18
Q

freq x period =

A

1

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19
Q

of the four waves, which has the shortest period:

  1. 12kHz
  2. 6,000 Hz
  3. 205 Hz
  4. 1 kHz
A

12 kHz = highest freq (shortest period)

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20
Q

of the 4 waves, which has the highest frequency?

A

**think, highest freq =

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21
Q

power and amplitude relationship

A

power = amp(^2) *squared

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22
Q

if the amplitude increases by factor of 3, what happens to the power

A

increases by a factor of 9

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23
Q

if the amplitude of a wave is decreased by half, what happens to the power?

A

decreases by 25% (1/4)

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24
Q

if the amp is decreased by a factor of 2, what happens to the power

A

decrease by a factor of 4

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25
Q

the concentration of energy in a sound beam

A

intensity

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26
Q

the rate of energy transfer or the rate at which work is being performed

A

power

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27
Q

the bigness of the wave

A

amplitude, power, intensity

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28
Q

difference between the max value and the avg value of an acoustic variable

A

amplitude

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29
Q

units of power

A

watts

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30
Q

amplitude, power, and intensity are determined by ___

A

the sound source (US system)

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31
Q

formula for intensity

A

power/ area

32
Q

relationship between intensity, power and amplitude

A 
intensity = power 
intensity = amp ^2
power = amp ^2
33
Q

when discussing relationships between amp, power, and intensity, the word “SQUARED” always follows the word

A

amplitude

34
Q

the distance or length of one complete cycle

A

wavelength

35
Q

wavelength is determined by ***

A

BOTH source and medium

36
Q

is wavelength adjustable?

A

no, not unless using a broadband transducer

37
Q

t/f: wavelength is the only parameter that is determined by both the source and the medium

A

true

38
Q

relationship between frequency and wavelength

A

inverse

-as freq increases, wavelength decreases

39
Q

the LONGER the wavelength the ___ the frequency

A

lower

40
Q

what is the wavelength of 1MHz sound in soft tissue

A

1.54mm

–> sound with freq 2MHz = 0.77 mm in soft tissue

41
Q

wavelength formula

A

(1.54mm/us) / (frequency in MHz)

42
Q

short wavelength = ___ freq = __ resolution

A

high frequency = better resolution

43
Q

speed of sound in soft tissue

A

1540m/s

44
Q

the rate at which a sound wave travels through a medium

A

propagation speed

45
Q

propagation speed is determined by

A

ONLY THE MEDIUM

46
Q

t/f: all acoustic waves travel at the same speed through a particular medium (the same medium)

A

TRUE

- prop speed depends ONLY on the medium, not on the nature of the sound wave

47
Q

as a general rule, sound travels fastest in ___, slower in ___, and slowest in ___

A

solids, liquids, gases

48
Q

formula for speed

A

freq x wavelength

49
Q

how does stiffness impact the speed of sound

A

it will increase the speed of sound

50
Q

as a material becomes stiffer, the speed of sound in the material will ___

A

increase

51
Q

in two otherwise identical medium, the speed of sound will be ___ in the stiffer medium

A

higher

52
Q

another word for bulk modulus

A

stiffness

53
Q

words that are opposite of stiffness

A

elasticity & compressibility

54
Q

describe a marshmallow in terms of bulk modulus, stiffness, elasticity, and compressibility

A
  • low bulk modulus
  • not stiff
  • highly elastic
  • highly compressible
55
Q

relationship between density and speed

A

Inverse

- as materials become MORE dense (heavier) the speed of sound decreases

56
Q

in which medium would sound travel faster: high density, or low density

A

low density

57
Q

if two mediums are equally stiff, the medium that is more dense will have a ___ propagation speed

A

lower

58
Q

when stiffness increases, speed ___

A

increases

**think S & S both start with the same letter so both go in same direction

59
Q

when density increases, speed ___

A

decreases

** S& D start with different letters, go in different directions

60
Q

what has a greater influence of prop speed: stiffness or density

A

stiffness

**air has a low stiffness but air travels slowly through it

61
Q

which of the following are considered acoustic variables:

  • freq
  • density
  • particle motion
  • temp
  • period
  • pressure
A

density, particle motion, pressure

62
Q

which are considered acoustic parameters:

  • freq
  • density
  • distance
  • pressure
  • period
A

frequency & period

63
Q

the effects of tissue on sound waves is called;

A

acoustic propagation properties

64
Q

effects of a medium on sound waves is called

A

acoustic propagation properties

65
Q

t/f: pulsed wave ultrasound produces anatomic images

A

FALSE

66
Q

the time from the start of a pulse to the end of that pulse is called

A

pulse duration

67
Q

pulse duration is determined by the

A

sound source ONLY

68
Q

pulse duration formula

A

cycles in each pulse * period

69
Q

pulse duration is directly related to (2 things) & indirectly related to (1 thing)

A 
directly 
-number of cycles 
-period 
indirectly 
-frequency
70
Q

what characteristics would increase the PD (pulse duration)?

A
  1. long periods

2. many cycles in 1 pulse

71
Q

what type of pulse is more desirable in medical imaging - long or short duration, why?

A

-short duration is more desirable because create images of greater accuracy & resolution (bc short pd = short period = higher freq)

72
Q

the distance that a pulse occupies in space from the start to the end

A

spatial pulse length

73
Q

what is SPL determined by

A

BOTH the sound source and medium

-b/c wavelength is in formula and wl if affected by both

74
Q

formula for SPL

A

cycles * wavelength

75
Q

SPL is directly related to (2) and indirectly related to (1)

A 
directly 
-# of cycles 
-wavelength 
indirectly 
-freq

CORE EXAM (quiz 1- physics) (2 decks)

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