Physics 2

As an ultrasound wave travels through the body, its amplitude usually: A. decreases B. increases C. remains the same D. cannot be determined

A

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

A

The amplitude of an acoustic wave decreases from 27 pascals to 9 pascals. If the initial power in the wave was 27 watts, what is the wave's final power? A. 3 watts B. 9 watts C. 1 watt D. none of the above

A

The maximum value of the density of an acoustic wave is 60 lb/in2 while the minimum density is 20 lb/in2. What is the amplitude of the wave? A. 20 lb/in2 B. 40 lb/in2 C. 60 lb/in2 D. none of the above

A

Typically, as an ultrasound wave travels through soft tissue, the power of the wave: A. decreases B. increases C. remains the same

A

What are the units of the transmitted intensity of a sound wave? A. W/cm2 B. watts C. dB D. none; it is unitless

A

What determines the initial amplitude of an ultrasound wave? A. the transducer B. the medium through which the sound travels C. both A and B D. neither choice A nor B

A

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 and B D. neither A nor B

A

What determines the period of an ultrasound wave? A. the transducer B. the medium through which the sound travels C. both A and B D. neither choice A nor B

A

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%

A

Which of the following units are appropriate to describe the period of an acoustic wave? (More than one answer may be correct.) A. minutes B. microseconds C. meters D. mm/microseconds E. cubic centimeters

A B

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

AB

As sound travels in the body, what typically happens to the intensity of the wave? A. increases B. decreases C. remains the same

B

Infrasound is defined as a sound with a frequency of _____. A. greater than 20,000 kHz B. less than 20 Hz C. greater than 10 MHz D. less than .02 MHz

B

What happens to the intensity of an ultrasound beam 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

B

What happens when the power in an ultrasound beam is unchanged, and at the same time, beam area doubles? A. doubles B. is halved C. is quartered D. remains the same

B

What is the range of periods commonly found in waves produced by ultrasound systems? A. 0.001 B. 0.06 to 0.5 microseconds C. 0.2 to 1 ms D. 10 to 1000 ns

B

What term describes the number of cycles that an acoustic variable completes in a second? A. period B. frequency C. pulse repetition period D. variable rate

B

The amplitude of an acoustic wave is increased. Which of the following will most likely remain unchanged? (More than one answer may be correct.) A. power B. frequency C. period D. intensity

B C

Compare two sound waves, A and B. The frequency of wave A is one-third that of wave B. How does the period of wave A compare with the period of wave B? A. A is one-third as long as B B. A is the same as wave B C. A is three times as long as B D. cannot be determined

C

Mathematically, when a number is squared, the number is multiplied by: A. 2 B. 0.5 C. itself D. 1.5

C

The frequency of a continuous acoustic wave is 5 MHz. The wave is then pulsed with a duty factor of 0.1. What is the new frequency? A. 0.5 B. 0.5 MHz C. 5 MHz D. 10 MHz

C

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

C

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/cm2

C

What are the units of intensity? A. watts B. watts/cm C. watts/cm2 D. dB

C

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 and B D. neither A nor B

C

When a sonographer increases the maximum imaging depth during an exam, what happens to the frequency? A. frequency increases B. frequency decreases C. remains unchanged

C

With standard ultrasound imaging, what happens to the period of a wave as it propagates? A. increases B. decreases C. remains the same

C

______ is the reciprocal of period. A. inverse period B. pulse repetition period C. frequency D. propagation period

C

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

D

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

D

Ultrasound is defined as a sound with a frequency of ____. A. greater than 20,000 kHz B. less than 1 kHz C. greater than 10 MHz D. greater than 0.02 MHz

D

What is characteristic of acoustic waves with frequencies exceeding 20,000 Hz when compared with waves having frequencies of less than 20,000 Hz? A. they travel more effectively in soft tissue B. they travel more rapidly C. they attenuate less than traveling in soft tissue D. humans can't hear them

D

What is characteristic of acoustic waves with frequencies of less than 20 Hz when compared with waves having frequencies of more than 20 Hz? A. they travel less effectively in soft tissue B. they travel more rapidly C. they attenuate more when traveling in soft tissue D. humans can't hear them

D

What is the range of frequencies emitted by transducers used in ultrasonic imaging? A. 1 to 3 MHz B. 1 to 1,000 kHz C. -10,000 to +10,000 Hz D. 2,000,000 to 15,000,000 Hz

D

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

D

Which of the following cannot be considered a unit of frequency? A. per day B. cycles/sec C. Hz D. hertz E. cycles

E

True or False? With standard ultrasound pulses, the frequency of the ultrasound changes significantly as the wave propagates through the body.

False

True or False? The sonographer has the ability to alter the period of an ultrasound wave that is produced by a basic transducer.

False

True of False? The period of an ultrasound wave is related to the frequency and is the same, regardless of whether the wave is pulsed or continuous.

True

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

True

True or False? If the periods of two waves are the same, then the frequencies of the waves must also be the same.

True

True or False? Waves in the ultrasound range behave in the same general manner as sound waves that are audible.

True

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

True

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.

True