Sound Waves

Question 1

______ is the time of the start of one cycle to the start of the next.

Answer 1

PERIOD

Question 2

What is the unit of period?

Answer 2

Time; seconds, milliseconds (mm)

Question 3

With diagnostic ultrasound what are the value of period?

Answer 3

one-tenth to one-half millionth of a second.

Question 4

What is period determined by?

Answer 4

Sound source only

Question 5

Can period be adjusted?

Answer 5

No

Question 6

_______ is the number of cycles that occur in one second?

Answer 6

Frequency

Question 7

What are the units of frequency?

Answer 7

Hertz (Hz)

Question 8

Convert the following to Hz.
1. 5 cycles/ second
2. 5,000 cycles/ second
3. 5,000,000 cycles/ second

Answer 8

1. 5 Hz
2. 5 KHz
3. 5 MHz

Question 9

What is the typical frequency range of ultrasound in a clinical setting?

Answer 9

2Mhz-15Mhz

Question 10

What is frequency determined by?

Answer 10

Sound source only

Question 11

Is frequency adjustable?

Answer 11

No

Question 12

What is the equation for frequency?

Answer 12

Frequency= cycles/ second

Question 13

If there are 10 cycles in 5 seconds, What is the frequency?

Answer 13

10/5=2
2Hz

Question 14

How many Hz is below human hearing?

Answer 14

Less than 20 Hz

Question 15

What does inaudible mean?

Answer 15

Can’t be heard

Question 16

What is the frequency of an infrasonic sound wave?

Answer 16

Less than 20 Hz

Question 17

What is the frequency of an audible sound wave?

Answer 17

Between 20 Hz and 20 KHz

Question 18

What is the frequency of ultrasound?

Answer 18

Greater than 20 KHz

Question 19

What is a frequency so high, humans can’t hear?

Answer 19

Ultrasonic

Question 20

What is the relationship between frequency and period?

Answer 20

Inversely related

Question 21

True or False. Are frequency and period reciprocals?

Answer 21

TRUE

Question 22

True or False. The lower the frequency the longer the period?

Answer 22

True
Period X Frequency=1

Question 23

Do higher or lower frequencies have shorter periods?

Answer 23

Higher frequencies

Question 24

Does a wave with a longer or shorter period have have a lower frequency?

Answer 24

Longer period

Question 25

What are the three parameters that describe size and strength of a sound?

Answer 25

Amplitude Intensity Power

Question 26

What term describes the difference between the maximum value and average value of an acoustic wave?

Answer 26

Amplitude

Question 27

What is amplitude describing when discussing a wave?

Answer 27

Bigness of a wave

Question 28

What are the units for amplitude?

Answer 28

Pressure (Pascals) Density ( g/cm3) distance (inches, cm)

Question 29

What is amplitude expressed in?

Answer 29

Decibels (Db)

Question 30

What are the typical values of amplitude in the clinical setting?

Answer 30

1MPa-3MPa

Question 31

What determines amplitude

Answer 31

Sound source orginally

Question 32

Is amplitude adjustable?

Answer 32

YES

Question 33

How is amplitude measured?

Answer 33

From the baseline to the maximum or minimum value

Question 34

What is the difference between maximum and minimum values of an acoustic variable?

Answer 34

Peak-to Peak amplitude

Question 35

What is twice the value of amplitude?

Answer 35

Peak-to-Peak amplitude

Question 36

What is the rate of energy transferred?

Answer 36

Power

Question 37

What describes the bigness of a wave?

Answer 37

Power Amplitude Intensity

Question 38

How is power and amplitude related?

Answer 38

Directly related

Question 39

What are the units of Power

Answer 39

Watts

Question 40

What is power proportional to?

Answer 40

Amplitude to the 3rd power

Question 41

What is power proportional to?

Answer 41

Amplitude

Question 42

What is power determined by?

Answer 42

Sound source only

Question 43

How is power related to frequency?

Answer 43

unrelated

Question 44

Does power increase or decrease as it propagates through tissue?

Answer 44

Decreases

Question 45

What determines the rate at which power decreases as sound travels through the body?

Answer 45

Characteristics of the medium and wave

Question 46

Is power adjustable?

Answer 46

Yes

Question 47

What does power equal?

Answer 47

Amplitude2

Question 48

If you increase the amplitude by a factor of 2 how does has power changed?

Answer 48

Power has increased 4 fold. (2x2=4)

Question 49

If you decrease the amplitude 1/4 its original value, how has power changed?

Answer 49

Power has decreased 1/16 (1/4 x1/4= 1/16)

Question 50

What is the concentration of energy in a sound beam?

Answer 50

Intensity

Question 51

How is intensity calculated?

Answer 51

Power/area

Question 52

What does intensity depend upon?

Answer 52

Power and area

Question 53

What are the units of power?

Answer 53

W/cm2

Question 54

What is intensity determined by?

Answer 54

Sound source

Question 55

What determines how the rate of intensity changes as it travels through the body?

Answer 55

Characteristics of the medium and shape of the sound beam

Question 56

Is intensity adjustable?

Answer 56

Yes

Question 57

How is intensity related to frequency?

Answer 57

unrelated