SPI Exam Review (Period and Frequency)

e. cycles

Which of the following cannot be considered a unit of frequency? a. per day b. cycles/sec c. Hz d. hertz e. cycles

c. A is three times as long as B

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

b. less than 20 Hz

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 0.02 MHz

true

T/F if the periods of two waves are the same, then the frequencies of the waves must also be the same.

true

T/F the period of an ultrasound wave is related to the frequency and is the same, regardless of whether the wave is pulsed or continuous.

false

T/F the sonographer has the ability to alter the period of an ultrasound wave that is produced by a basic transducer.

true

T/F waves in the ultrasound range behave in the same general manner as sound waves that are audible.

false

T/F with standard ultrasound pulses, the frequency of the ultrasound changes significantly as the wave propagates through the body.

c. 5 MHz

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

d. greater than 0.02 MHz

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

a. the transducer

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. the transducer

What establishes the frequency 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

d. humans can't hear them

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 when traveling in soft tissue d. humans can't hear them

d. humans can't hear them

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. 2,000,000 to 15,000,000 Hz

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

b. 0.06 to 0.5 us

What is the range of periods commonly found in waves produced by ultrasound systems? a. 0.001 to 1 s b. 0.06 to 0.5 us c. 0.2 to 1 ms d. 10 to 100 ns

b. frequency

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

c. remains unchanged

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

a and b

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/us e. cubic centimeters

c. remains the same

With standard ultrasonic imaging, what happens to the period of a wave as it propagates? a. increases b. decreases c. remains the same

c. frequency

__________ is the reciprocal of period. a. inverse period b. pulse repetition period c. frequency d. propagation speed