Physics 111 Chapter 2

Question 1

A wave is a traveling variation in quantities called wave________________

Answer 1

variables

Question 2

Ultrasound is sound with a frequency greater than

Answer 2

20,000

Question 3

Ultrasound is sound with a frequency greater than

Answer 3

20,000 Hz

Question 4

______________ is the time it takes for one cycle to occur.

Answer 4

Time

Question 5

Wavelength is the length of _____________ over which one cycle occurs.

Answer 5

Space

Question 6

Sound requires a ______________ through which to travel.

Answer 6

Medium

Question 7

Stiffer media have _______________ sound speeds

Answer 7

Higher

Question 8

Propagation speed is primarily determined by the ______________ of the medium.

Answer 8

Stiffness

Question 9

Ultrasound pulses contain a range of frequencies called the _______________.

Answer 9

Bandwidth

Question 10

Regions of lower pressure and density are called

Answer 10

rarefactions

Question 11

________________ area even and odd multiples of the fundamental frequency

Answer 11

Harmonics

Question 12

Doppler ultrasound pulses are typically _________ cycles long

Answer 12

5-30

Question 13

The fraction of time that pulsed ultrasound is on is called

Answer 13

Duty Factor

Question 14

The rate at which energy passes through a unity area is called

Answer 14

Intensity

Question 15

As sound travels, the reduction of amplitude and intensity of the wave is called

Answer 15

attenuation

Question 16

The average propagation speed in human soft tissue is ________________

Answer 16

1540m/s

Question 17

If you switch to a lower frequency for penetration, the wavelength of the transducer ______________

Answer 17

Increases

Question 18

1000 Hz is equal to _______________ kHz

Answer 18

1

Question 19

If the beam power increases, intensity ___________________

Answer 19

Increases

Question 20

If the beam area decreases, the intensity ___________

Answer 20

Increases

Question 21

Attenuation increases with increasing ___________

Answer 21

Frequency

Question 22

For perpendicular incidence, the incidence angle is______________

Answer 22

0

Question 23

The ______________ _____________ is the number of pulses that occur in single second

Answer 23

Pulse repetition frequency

Question 24

If the number of cycle in a pulse is reduced, the pulse duration _______________

Answer 24

is decreased

Question 25

Amplitude and Intensity are indicators of the the sound wave's _________________

Answer 25

strength

Question 26

Duty factors for sonography are typically in the range of _____________________

Answer 26

0.1% - 1.0%

Question 27

Impedance in equal to density multiplied by ______________

Answer 27

propagation speed

Question 28

The unit for impedance is

Answer 28

rayl

Question 29

If the propagation speed through the second medium is greater than through the first medium, the transmission angle is ______________

Answer 29

greater than the incidence angle

Question 30

What does 3 dB of attenuation mean?

Answer 30

One half the original intensity

Question 31

Lateral position errors occur on an image due to sound _______________

Answer 31

refraction

Question 32

The proportion of intensity to amplitude is

Answer 32

squared

Question 33

What units are used to quantify attenuation?

Answer 33

dB

Question 34

If intensity reflection coefficient increases, intensity transmission coefficient _________________

Answer 34

decreases

Question 35

In oblique incidence, the ___________ and _____________ angles are always equal

Answer 35

incidence; reflection

Question 36

The liquid suspensions that have been developed can injected into the circulation intravenously to increase _______________

Answer 36

echogenicity

Question 37

Intensity is equal to the power of a wave divided by the _______________ over which the power is spread

Answer 37

area

Question 38

Amplitude is the maximum variation that occurs in an acoustic ________________

Answer 38

variable

Question 39

The dominant factor contributing to attenuation of ultrasound in soft tissue is

Answer 39

absorption

Question 40

Almost all ultrasound contrast agents contain

Answer 40

gas microbubbles

Question 41

Ultrasound systems use propagation speed to determine

Answer 41

echo location of the display

Question 42

_________________ determines how fast images genetated

Answer 42

Pulse repetition frequency

Question 43

Interfaces that scatter ultrasound energy are usually considered those that ate equal to smaller than the ________________

Answer 43

Wavelength

Question 44

Sound is a

Answer 44

mechanical longitudinal wave

Question 45

_______________ media have higher sound speeds

Answer 45

Stiffer

Question 46

_________________ frequencies are generated as sound travels through tissue

Answer 46

Harmonic

Question 47

When frequency increases, period

Answer 47

decreases

Question 48

A ______________ is one complete variation in pressure

Answer 48

cycle

Question 49

_______________ limits imaging depth

Answer 49

Attenuation

Question 50

The shorter the pulse, the broader the

Answer 50

bandwidth

Question 51

With doppler techniques, the operator controls the ______________________________

Answer 51

pulse repetition frequency

Question 52

____________pulses improve the quality of sonographic images

Answer 52

Shorter

Question 53

For each centimeter of distance, the pulse round trip time is equal to

Answer 53

13 ms

Question 54

From given values for propagation speed and frequency _______________ can be calculated

Answer 54

Wavelength

Question 55

Sound travels most slowly in

Answer 55

Gases

Question 56

Sound travels fastest in

Answer 56

steel

Question 57

Waves can carry ____________ from one place to another

Answer 57

information

Question 58

The time from the beginning of one pulse to the beginning of the next is

Answer 58

Pulse repetition period

Question 59

Spatial pulse length equals the number of cycle in the pulse multiplied by________________

Answer 59

wavelength

Question 60

Beam width can be reduced by focusing to improve

Answer 60

lateral resolution