Phy-125 Test 2

Front 1

A measure of the ability to cause some type of change:

Back 1

Energy

Front 2

A _______ involves a motion that is repeated over & over.

Back 2

vibration

Front 3

What kind of wave involves the vibration of a medium and cannot travel in a vacuum.

Back 3

mechanical

Front 4

What kind of wave involves the vibration of electric & magnetic fields & can travel in a vacuum.

Back 4

electromagnetic

Front 5

________ waves vibrate in a direction parallel to the propagation direction.

Back 5

longitudinal

Front 6

________ waves travel in a direction perpendicular to the propagation direction.

Back 6

transverse

Front 7

Sound is a _______, _______ wave

Back 7

mechanical, longitudinal

Front 8

A _______ zone is where particles of a medium move apart, creating a low pressure zone. Thinning of air.

Back 8

rarefaction

Front 9

A _______ zone is where particles of a medium move closer together, creating a high pressure zone.

Back 9

compression

Front 10

The acoustic _______ are the ones that cycle in value for a sound wave.

Back 10

variables

Front 11

List the acoustic variables:

Back 11

pressure, density, particle motion

Front 12

The acoustic _______ describe the characteristics of a sound wave.

Back 12

parameters

Front 13

List the acoustic parameters:

Back 13

period, frequency, propagation speed, wavelength, amplitude, power, & intensity

Front 14

Which acoustic parameters are associated with distance & time?

Back 14

period, frequency, wave (propagation) speed, & wavelength

Front 15

Which acoustic parameters indicate how loud the sound will be?

Back 15

amplitude, power, & intensity

Front 16

A ______ is one full completion of a repeated motion.

Back 16

cycle

Front 17

_______ is the time to complete a cycle.

Back 17

Period

Front 18

_______ is the number of cycles completed per unit time.

Back 18

Frequency

Front 19

The unit of frequency is:

Back 19

Hertz

Front 20

Frequency & period depend only on ________.

Back 20

the source

Front 21

Sound below 20 Hz:

Back 21

infrasound

Front 22

Sound above 20,000 Hz (20 kHz)

Back 22

ultrasound

Front 23

Common diagnostic ultrasound frequencies are between:

Back 23

2 & 15 MHz

Front 24

Frequency & period are associated with ______, not ______.

Back 24

time, distance

Front 25

How fast the wave propagates from its source:

Back 25

wave (propagation) speed

Front 26

What does wave (propagation) speed determine?

Back 26

how much space is vibrated in a given amount of time as the wave leaves the source

Front 27

Wave (propagation) speed depends only on:

Back 27

medium of travel

Front 28

Wave (propagation) speed is based on the ______ & _____ of the medium.

Back 28

stiffness & density

Front 29

When the stiffness of a medium increases, the sound wave propagates ________.

Back 29

faster

Front 30

When the density of a medium increases, the sound wave propagates _______.

Back 30

slower

Front 31

wave speed in lung:

Back 31

500 m/s (.5 mm/microsecond)

Front 32

wave speed in soft tissue:

Back 32

1540 m/s (1.54 mm/microsecond)

Front 33

wave speed in bone:

Back 33

3500 m/s (3.5 mm/microsecond)

Front 34

Wave (propagation) speed is associated with:

Back 34

both distance AND time

Front 35

The distance traveled during one cycle:

Back 35

wavelength

Front 36

Wavelength is calculated as:

Back 36

propagation speed / frequency (v/f)

or distance = speed x time (vT))

Front 37

Wavelength depends on both ______ & ______.

Back 37

source & medium of travel

Front 38

Wavelength is associated with:

Back 38

distance NOT time

Front 39

Measures the ability of a substance to cause electric & magnetic phenomena:

Back 39

Electromagnetic (EM) charge

Front 40

A transducer converts mechanical energy into electric energy & vice-versa. This is called:

Back 40

the piezoelectric effect

Front 41

The transducer is made so that its thickness is about ______ the wavelength of the sound to be produced.

Back 41

half

Front 42

Transducers are typically how thick?

Back 42

.2 to 1 mm

Front 43

Transducers typically have propagation speeds of:

Back 43

4 to 6 mm/microsecond

Front 44

The thinner the transducer element, the ______ the wavelength, so that the frequency is ______.

Back 44

smaller; higher

Front 45

A _____ is the odd-numbered or the even-numbered horizontal scan lines on the display screen.

Back 45

field

Front 46

A ______ is about half the display screen.

Back 46

field

Front 47

A ______ is two fields.

Back 47

frame

Front 48

The whole display screen is called a ______.

Back 48

frame

Front 49

A _______ is displaying one frame.

Back 49

freeze-frame

Front 50

Displaying several frames over & over in a loop (like a GIF):

Back 50

cine review

Front 51

________ magnification is viewing a small group of pixels that are expanded to fill the screen, which increases pixel size.

Back 51

Read

Front 52

________ magnification is rewriting a smaller field of view into memory without changing pixel size.

Back 52

Write