Chapters 5-8 Jessica

Question 1

What is the log of 1000

Answer 1

3

Question 2

A drop in intensity to one quarter of its original value is _______ dB?

Answer 2

6

Question 3

dBs represent a ______ change in intensity?

Answer 3

relative

Question 4

If the initial intensity is less than the final intensity, then the gain in dB is ______(+or-)?

Answer 4

positive

Question 5

-10 dB means that the intensity is reduced to ____ of its original value?

Answer 5

one-tenth

Question 6

Which of the following has greater attenuation?
a. long distance, low frequency
b. long distance, high frequency
c. short distance, low frequency
d. short distance, high frequency

Answer 6

b

Question 7

Which of the following results in the most attenuation?
a. 4MHz, 2 cm path length
b. 4 MHz, 8 cm path length
c. 6 MHz, 8 cm path length
d. 6 MHz, 4 cm path length

Answer 7

c

Question 8

As frequency increases, attenuation coefficient____?

Answer 8

increases

Question 9

What is the unit for impedance?

Answer 9

Rayls (Z)

Question 10

What are the 3 components of attenuation?

Answer 10

absorption, reflection, scattering

Question 11

What component of attenuation is the dominant contributor to attenuation?

Answer 11

Absorption

Question 12

Total attenuation is related to ____ and _____?

Answer 12

path length and frequency

Question 13

Attenuation in air is ____ than in soft tissue?

Answer 13

much greater than

Question 14

What are the units of attenuation?

Answer 14

dB

Question 15

As the path length increases, the attenuation coefficient _____?

Answer 15

remains the same

Question 16

Attenuation coefficient is directly related to____?

Answer 16

frequency

Question 17

Rayleigh scattering is related to _____?

Answer 17

frequency^4

Question 18

A sound wave with an intensity of 75 W/cm-squared, strikes a boundary and is totally reflected. What is the intensity reflection coefficient?

Answer 18

100%

Question 19

A sound wave with an intensity of 75 W/cm-squared, strikes a boundary and is totally reflected. What is the reflected intensity?

Answer 19

75 W/ cm-squared

Question 20

Which of the following has the greatest attenuation and the slowest speed?
a.bone b.tendon
c. fat d. air

Answer 20

d

Question 21

A sound wave hits a boundary between two media with different impedances. The angle of incidence is non-orthogonal. What happens to the sound?

Answer 21

some of the sound MAY be reflected

Question 22

What is the meaning of a 9 dB change?

Answer 22

8 times bigger