Amplitude, Power, & Intensity

Question 1

What determines the initial amplitude of an ultrasound wave?

a. the transducer
b. the medium through which the sound travels
c. both a. & b.
d. neither choice a. or b.

Answer 1

a. the transducer

Question 2

True or False?

With standard diagnostic imaging instrumentation, the sonographer has the ability to vary the amplitude of a sound wave produced by the transducer.

Answer 2

True

Question 3

As an ultrasound wave travels through the body, its amplitude usually:

a. decreases
b. increases
c. remains the same
d. cannot be determined

Answer 3

a. decreases

Question 4

Which of the following are acceptable units for the amplitude of an acoustic wave? (more than one answer may be correct).

a. cm
b. pascals
c. gauss
d. watts

Answer 4

a. cm

b. pascals

Question 5

The maximum value of the density of an acoustic wave is 60 lb/in^2 while the minimum density is 20 lb/in^2. What is the amplitude of the wave?

a. 20 lb/in^2
b. 40 lb/in^2
c. 60 lb/in^2
d. none of the above

Answer 5

a. 20 lb/in^2

Question 6

The power of an ultrasound wave can be reported with which of the following units? (more than one answer may be correct).

a. watts/square centimeter
b. dB/cm
c. watts
d. kg/cm^2

Answer 6

c. watts

Question 7

Typically, as an ultrasound wave travels through soft tissue, the power of the wave:

a. decreases
b. increases
c. remains the same

Answer 7

a. decreases

Question 8

True or False?

A sonographer can routinely change the power of a wave emitted by a transducer used in diagnostic ultrasonic imaging.

Answer 8

True

Question 9

Mathematically, when a number is squared, the number is multiplied by:

a. 2
b. 0.5
c. itself
d. 1.5

Answer 9

c. itself

Question 10

The final amplitude of an acoustic wave is reduced to one-half of its original value. The final power is ____ the original power.

a. the same as
b. one-half
c. double
d. none of the above

Answer 10

d. none of the above

Question 11

The amplitude of an acoustic wave decreases from 27 pascals to 9 pascals. If the initial power in the wave has 27 watts, what is the wave’s final power?

a. 3 watts
b. 9 watts
c. 1 watt
d. none of the above

Answer 11

a. 3 watts

Question 12

The intensity of an ultrasound beam is defined as the ____ in a beam ____ by the ____ of the beam.

a. power, multiplied, diameter
b. amplitude, divided, area
c. power, divided, area
d. amplitude, multiplied, circumference

Answer 12

c. power, divided, area

Question 13

As sound travels in the body, what typically happens to the intensity of the wave?

a. increases
b. decreases
c. remains the same

Answer 13

b. decreases

Question 14

What are the units of intensity?

a. watts
b. watts/cm
c. watts/cm^2
d. dB

Answer 14

c. watts/cm^2

Question 15

True or False?

With diagnostic ultrasonic imaging instruments, the operator can alter the intensity of an ultrasound beam produced by a transducer.

Answer 15

True

Question 16

What determines the initial intensity of an ultrasound beam?

a. the source of the sound wave
b. the medium through which the sound travels
c. both a. & b.
d. neither a. or b.

Answer 16

a. the source of the sound wave

Question 17

What determines the intensity of an ultrasound beam after it has traveled through the body?

a. the sound wave’s source
b. the medium through which the sound travels
c. both a. & b.
d. neither a. nor b.

Answer 17

c. both a. & b.

Question 18

What are the units of the transmitted intensity of a sound wave?

a. W/cm^2
b. watts
c. dB
d. none, it is unitless

Answer 18

a. W/cm^2

Question 19

What happens when the power in an ultrasound beam is unchanged, and at the same time, the beam area doubles?

a. doubles
b. is halved
c. is quartered
d. remains the same

Answer 19

b. is halved

Question 20

What happens to an acoustic beam’s intensity when the power in the beam increases by 25% while the cross-sectional area of the beam remains the same?

a. it increases by 25%
b. increases by 75%
c. it increases by 50%
d. decreases by 25%

Answer 20

a. it increases by 25%

Question 21

When the power in an acoustic beam is doubled and the cross-sectional area of the beam is halved, then the intensity of the beam is:

a. doubled
b. halved
c. quartered
d. four times larger

Answer 21

d. four times larger

Question 22

What happens to the intensity of an ultrasound team when the beam’s cross-sectional area remains unchanged while the amplitude of the wave triples?

a. it triples
b. increases ninefold
c. remains the same
d. none of the above

Answer 22

b. increases ninefold

Question 23

If the power of the beam is tripled while the cross-sectional area of the beam remains the same, the intensity ___.

a. triples
b. increases ninefold
c. remains the same
d. none of the above

Answer 23

a. triples

Question 24

The amplitude of an acoustic wave is increased. Which of the following will most likely remain unchanged? (more than one answer my be correct).

a. power
b. frequency
c. period
d. intensity

Answer 24

b. frequency

c. period

Question 25

A sonographer adjusts the output power of the wave emitted by the transducer. Which of the following also changes? (more than one answer may be correct).

a. pulse repetition period
b. PRF
c. propagation speed
d. intensity

Answer 25

d. intensity