Ultrasound Physics: Chapter 2 Waves

Front 1

Repetitious waves are a _______ transfer of energy.

Back 1

cyclical

Front 2

The major classification of waves are _____ and _____.

Back 2

electromagnetic and mechanical

Front 3

An electromagnetic wave does not need a _____ to propagate.

Back 3

medium

Front 4

A _____ wave needs a medium to propagate.

Back 4

mechanical

Front 5

There can be no _____ waves is a vacuum.

Back 5

mechanical

Front 6

A vacuum is an absence of a _____.

Back 6

medium

Front 7

There is no sound in a ______, since there is no medium.

Back 7

vacuum

Front 8

Two classifications of mechanical waves are _____ and _____.

Back 8

transverse and longitudinal

Front 9

In a _____ wave, particle motion is perpendicular or "transverse" to the wave direction.

Back 9

transverse

Front 10

In a _____ wave, the particle motion is back and forth "longitudinally" or in the same direction as the wave propagation.

Back 10

longitudinal

Front 11

Sound is a _____, mechanical wave.

Back 11

longitudinal

Front 12

A longitudinal wave has areas or _____ and compression.

Back 12

rarefaction

Front 13

An area of _____ is where the particles are farther apart than the normal state.

Back 13

rarefaction

Front 14

An area of _____ is where the particles are closer together than the normal state.

Back 14

compression

Front 15

Not all waves need a medium to propagate; _____ electromagnetic waves can operate in a vacuum.

Back 15

electromagnetic

Front 16

_____ is a way of specifying how fast a wave is cyclically varying.

Back 16

frequency

Front 17

The unit of frequency is _____ which is an abbreviation for cycles per second.

Back 17

Hertz

Front 18

Frequency has units which are the inverse of _____, or one divided by seconds, also called Hz.

Back 18

time

Front 19

The number of times a longitudinal wave reaches maximum compression and rarefaction per time is called the _____.

Back 19

frequency

Front 20

The reciprocal of frequency is the _____.

Back 20

period

Front 21

The period has units of _____.

Back 21

time

Front 22

The reciprocal of the _____ is frequency. Frequency has units of Hertz.

Back 22

period

Front 23

The _____ is the time between cycles of peak compression in a longitudinal wave such as sound.

Back 23

period

Front 24

The _____ between cycles of peak compression is the same as the time between cycles of peak rarefaction.

Back 24

time

Front 25

The ____ is the time between cycles of peak rarefaction.

Back 25

period

Front 26

Frequency and period are _____.

Back 26

reciprocals

Front 27

Hertz and _____ or seconds are inversely related.

Back 27

time

Front 28

Since frequency and period are inversely related, if the frequency increase the period _____.

Back 28

decreases

Front 29

A shorter period means higher _____.

Back 29

frequency

Front 30

A lower _____ means a longer period.

Back 30

frequency

Front 31

The ______ is the physical measure of distance between wave peaks or similarly wave minima.

Back 31

wavelength

Front 32

Wavelength is a measure of _____ and therefore in the metric system has units of meters.

Back 32

distance

Front 33

The period is a measure of ____ between peaks whereas the wavelength is a measure of distance between peaks.

Back 33

time

Front 34

Frequency and _____ are related through the wave propagation velocity.

Back 34

wavelength

Front 35

The propagation of _____ has units of meters/second.

Back 35

velocity

Front 36

The ______ is a measure of how fast a wave will travel.

Back 36

propagation velocity

Front 37

The propagation of velocity (c) equals the frequency (f) times the _____.

Back 37

wavelength

Front 38

For a given propagation velocity, if the frequency increases, the _____ must decrease.

Back 38

wavelength

Front 39

For a given propagation velocity, if the frequency decreases, the wavelength must _____.

Back 39

increase

Front 40

Frequency and wavelength have a _______ relationship.

Back 40

inverse

Front 41

If the propagation velocity changes, and the frequency is not changed, the ______ must change.

Back 41

wavelength

Front 42

The ______ of a signal is a measure of how big or loud it is.

Back 42

amplitude

Front 43

The ______ is determined as the maximum variation from the mean.

Back 43

amplitude

Front 44

mean

Back 44

(maximum+minimum)/2

Front 45

If the _____ of an ultrasound echo increases, the B-mode image will get brighter.

Back 45

amplitude

Front 46

Possible units of amplitude are:

Back 46

Pascals, degrees Celsius, meters, kg/m

Front 47

A wave which has a physical interaction with the medium is called a _______ wave.

Back 47

mechanical

Front 48

A change within the medium caused by a wave is called a ______.

Back 48

variable

Front 49

List the 4 acoustic variables:

Back 49

pressure, distance, temperature, density

Front 50

Units of pressure are:

Back 50

Pascals, Atmospheres, mmHG, kg/m2, lbs/in2

Front 51

Units of distance are:

Back 51

meters, feet, miles, yards, etc

Front 52

Units of temperature are:

Back 52

degrees Celsius, degrees Fahrenheit, degrees Kelvin

Front 53

Units of density are:

Back 53

mass/volume, such as kg/m3 or lbs/ft3

Front 54

Changes in the acoustic variables are the result of the ____ interaction of the acoustic wave and the medium.

Back 54

mechanical