Ch. 2 Flashcards Preview

Physics Final > Ch. 2 > Flashcards

Flashcards in Ch. 2 Deck (50):
1

______ is the amount of complete cycles per second.
a. wavelength
b. period
c. frequency
d. propagation speed

c. frequency

2

If frequency increases, each cycle (period) _______.
a. increases
b. decreases
c. remains unchanged
d. doubles

b. decreases

3

Wavelength is the ______ over which one cycle occurs.
a. time
b. length
c. area
d. power

b. length

4

Propagation speed is the speed at which a wave ______ through a medium.
a. cycles
b. refracts
c. travels
d. reflects

c. travels

5

Stiffer media have _____ sounds speeds.
a. lower
b. higher
c. stiffness does not change the prop. speed
d. sound cannot propagate through the stiffer media

b. higher

6

Frequency _______ wavelength.
a. is directly proportional to
b. is inversely proportional to
c. is equal to
d. has no bearing on

b. is inversely proportional to

7

Ultrasound pulses contain a range of frequencies called the ________.
a. fundamental frequencies
b. duty factor
c. pulse repetition frequencies
d. bandwidth

d. bandwidth

8

Pulsed ultrasound consists of _____ separated by ______ of time.
a. frequencies; cycles
b. pulses; cycles
c. pulses; gaps
d. cycles; pulses

c. pulses; gaps

9

Pulse repetition frequency (PRF) refers to the _____ of pulses occurring in one second.
a. speed
b. number
c. type
d. cycle

b. number

10

All of the following are acoustic variables except ______:
a. pressure
b. density
c. compression
d. particle vibration

c. compression

11

The fraction of time that pulsed ultrasound is on is called ____.
a. pulse repetition period
b. duty factor (DF)
c. period
d. spatial pulse length

b. duty factor (DF)

12

As sound travels, the reduction in amplitude and intensity of the wave is called _____.
a. scattering
b. attenuation
c. absorption
c. reflection

b. attenuation

13

What would be the frequency for a .22 mm wavelength in soft tissue?
a. 5.0 MHz
b. 7.0 MHz
c. 7.5 MHz
d. 3.5 MHz

b. 7.0 MHz

14

What is the pulse duration of a four-cycle pulse in a period of 0.5 us?
a. 0.2 us
b. 2.0 us
c. 1.25 us
d. .125 us

b. 2.0 us

15

***skip***

***skip***

16

The velocity of sound in human soft tissue is assumed to be a constant. If you employ a 7.5 MHz transducer, what is the wavelength of the sound?
a. .11 mm
b. .20 mm
c. .025 mm
d. 1.1 mm

b. .20 mm

17

20 kHz is equal to ____ Hz.
a. 200
b. 2000
c. 20,000
d. 200,000

c. 20,000

18

1000 Hz is equal to ___ kHz.
a. 1
b. 10
c. 1000
d. .1

a. 1

19

What is the attenuation coefficient for a 5.0 MHz transducer in soft tissue?
a. .25 dB/cm
b. .1 dB/cm
c. 2.5 dB/cm
d. 10 dB/cm

c. 2.5 dB/cm

20

At what depth does a 3.0 MHz transducer have an attenuation of 9 dB?
a. 6.0 mm
b. .6 cm
c. 6.0 cm
d. .6 mm

c. 6.0 cm

21

What is the attenuation of a 7.5 MHz transducer at a depth of 20 mm?
a. 7.5 dB
b. 5.0 dB
c. .53 dB
d. 75 dB

a. 7.5 dB

22

If beam power increases, intensity ______.
a. increases
b. decreases
c. doubles
d. remains unchanged

a. increases

23

Attenuation increases with increasing _______.
a. wavelength
b. frequency
c. power
d. pressure

b. frequency

24

For perpendicular incidence, the incidence angle is _______.
a. 50
b. 10
c. 90
d. 0

d. 0

25

The pulse repetition frequency is the number of pulses that occur in a single ______.
a. microsecond
b. second
c. millisecond
d. pulse

b. second

26

Calculate the pulse duration for a 3.0 MHz transducer in soft tissue with a four-cycle pulse.
a. 1.2 us
b. 1.3 us
c. 12 us
d. 13 us

b. 1.3 us

27

Continuous wave (CW) Doppler has a duty factor of _____ %.
a. 1.0
b. .10
c. 100
d. 10

c. 100

28

What is the spatial pulse length of a four-cycle pulse with a wavelength of .1 mm?
a. 4.0 mm
b. .4 cm
c. .4 mm
d. 40 mm

c. .4 mm

29

Duty factors for sonography are typically in the range of _____ %.
a. .1 - 1.0
b. .5 - 2.0
c. 25 - 50
d. 90 - 11

a. .1 - 1.0

30

Impedance is equal to density multiplied by ______.
a. propagation speed
b. wavelength
c. path length
d. stiffness

a. propagation speed

31

The unit for impedance is _____.
a. W/cm^2
b. dB/cm
c. watt
d. rayl

d. rayl

32

The even harmonics of 2 MHz are _____MHz.
a. 2 , 4 , 6
b. 4, 8 , 12
c. 2 , 4 , 8
d. 4 , 6 , 8

b. 4 , 8 , 12

33

If the propagation speed through the second medium is greater than through the first medium, the transmission angle is _____.
a. less than the incidence angle
b. equal to the incidence angle
c. greater than the incidence angle
d. unrelated to teh incidence angle

c. greater than the incidence angle

34

The distance to the reflector (D) in soft tissue with a round-trip time of 39 us is _____.
a. 3 mm
b. 3 cm
c. 13 mm
d. 13 cm

b. 3 cm

35

What does 3 dB of attenuation mean?
a. one half the original intensity
b. one third the original intensity
c. Three decibels more than the original intensity
d. increasing amplitude

a. one half the original intensity

36

Which of the following is not a term used to describe continuous wave ultrasound?
a. pulse duration
b. frequency
c. wavelength
d. propagation speed

a. pulse duration

37

Lateral position errors occur on an image due to sound _____.
a. reflection
b. attenuation
c. refraction
d. transmission

c. refraction

38

The proportion of intensity to amplitude is _____.
a. tripled
b. halved
c. squared
d. quadrupled

c. squared

39

Attenuation encompasses ______.
a. absorption
b. scattering
c. reflection
d. all of the above

d. all of the above

40

What units are used to quantify attenuation?
a. unitless
b. dB/cm
c. dB
d. rayls

c. dB

41

If intensity reflection coefficient increases, intensity transmission coefficient _____/
a. decreases
b. increases
c. remains unchanged
d. is equal to the intensity reflection coefficient

a. decreases

42

For perpendicular incidence and equal impedances between media, there is no ____ and the ______ intensity equals the incident intensity.
a. transmission; reflected
b. refelction; transmitted
c. transmission; transmitted
d. refelction; reflected

b. reflection; transmitted

43

The distance to a reflector in soft tissue is 15 cm. What is the round-trip time to this depth?
a. 19.5 us
b. 195 us
c. 1.15 us
d. 11.5 us

b. 195 us

44

In oblique incidence, the ______ and ______ angles are always equal.
a. transmitted; reflected
b. normal; transmitted
c. incidence; reflection
d. incidence; transmitted

c. incidence; reflection

45

The liquid suspensions that have been developed can be injected into the circulation intravenously to increase _____.
a. wavelength
b. propagation speed
c. impedance
d. echogenicity

d. echogenicity

46

If an echo returns 104 us after a pulse was emitted by a transducer, at what depth is the structure that produced the echo located?
a. .8 mm
b. 80 cm
c. 8.0 mm
d. 8.0 cm

d. 8.0 cm

47

In oblique incidence, when the propagation speeds on either side of the boundary are different, which incidence is most likely to occur?
a. transmitted
b. refracted
c. reflected
d. attenuated

b. refracted

48

Intensity is equal to the power of a wave divided by the ___ over which the power is spread.
a. diameter
b. radius
c. area
d. width

c. area

49

Amplitude is the maximum variation that occurs in an acoustic ___.
a. frequency
b. medium
c. variable
d. propagation speed

c. variable

50

Which of the following determines how fast images are generated?
a. pulse duration
b. duty factor
c. pulse repetition frequency
d. pulse repetition period

c. pulse repetition frequency