Chapter 3

Question 1

What are the units of wavelength?

Answer 1

millimeters (mm)

Question 2

What are the units of frequency?

Answer 2

hertz

Question 3

What are the units of intensity?

Answer 3

Watts/cm2

Question 4

What are the units of propagation speed?

Answer 4

meters/second

Question 5

What are the units of period?

Answer 5

seconds or time

Question 6

What are the units of power?

Answer 6

Watts (W)

Question 7

Does the medium/ the sound source/ both determine this parameter?
wavelength

Answer 7

both

Question 8

Does the medium/ the sound source/ both determine this parameter?
frequency

Answer 8

sound source

Question 9

Does the medium/ the sound source/ both determine this parameter?
intensity (initial)

Answer 9

sound source

Question 10

Does the medium/ the sound source/ both determine this parameter?
propagation speed

Answer 10

medium

Question 11

Does the medium/ the sound source/ both determine this parameter?
period

Answer 11

sound source

Question 12

Does the medium/ the sound source/ both determine this parameter?
power (initial)

Answer 12

sound source

Question 13

Does the medium/ the sound source/ both determine this parameter?
amplitude (initial)

Answer 13

sound source

Question 14

When using a ultrasound system and transducer can this be changed by the operator?
wavelength

Answer 14

cannot

Question 15

When using a ultrasound system and transducer can this be changed by the operator?
frequency

Answer 15

cannot

Question 16

When using a ultrasound system and transducer can this be changed by the operator?
intensity

Answer 16

can

Question 17

When using a ultrasound system and transducer can this be changed by the operator?
propagation speed

Answer 17

cannot

Question 18

When using a ultrasound system and transducer can this be changed by the operator?
period

Answer 18

cannot

Question 19

When using a ultrasound system and transducer can this be changed by the operator?
power

Answer 19

can

Question 20

When using a ultrasound system and transducer can this be changed by the operator?
amplitude (initial)

Answer 20

can

Question 21

True or False. A wave with a frequency of 15,000 MHz is ultrasonic

Answer 21

True. Ultrasound is defined as any wave with a frequency greater than 20,000 hertz. 15,000 MHz is a frequency of 15,000,000,000 Hz.

Question 22

True of False. If the amplitude of a wave is increased to 3 times its original value, the intensity is increased by 6 times.

Answer 22

False. Intensity is proportional to the amplitude squared. If we triple the amplitude, we increase the intensity by a factor of nine.

Question 23

Questions 6-12 needs to be studied in book

Question 24

True or False. If the power of a wave is halved, the intensity is reduced to one-fourth its original value.

Answer 24

False. Intensity is the power of a beam divided by its cross sectional area. If we halve the power, we will halve the intensity.

Question 25

True or False. Propagation speed increases as frequency increases.

Answer 25

False. Propagation speed is determined by the medium only. Frequency and speed are unrelated.

Question 26

Medium 1 has a density of 9 and a stiffness of 6. Medium 2 has a density of 8 and a stiffness of 6. In which medium will sound travel slower?

Answer 26

Medium 1. Since both media have the same stiffness, the medium with the greater density has the lower propagation speed.

Question 27

Which of the following characteristics will create the fastest speed of sound?
A. high density, high stiffness
B. low density, high stiffness
C. high density, low stiffness
D. low density, low stiffness

Answer 27

B. speed is inversely proportional to density and directly proportional to stiffness