Understanding Ultrasound Physics - SPI Exam Review - Period and Frequency

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

E. cycles The term cycles informs us of the number of events, but does not inform us of the duration of time required for those events to occur. Choice E is incomplete, and is not a unit of frequency. All the other choices reveal that a number of events took place in a specific time span.

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

A. the transducer when created by a transducer, an ultrasound wave has a specific frequency. The frequency is not determined by the medium through which the sound travels. only the sound source (the transducer) establishes the wave's frequency.

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. The sound source (the transducer) that produces an acoustic signal determines the period of a wave. The wave's period is unrelated to the medium through which the sound travels, and will not change as the wave moves from one medium to another.

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. frequency This is the definition of the term frequency. Frequency can also be thought of as the number of regularly occurring events in a specific time.

The frequency of 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. 5 MHz Frequency is the reciprocal of the period. The fact that a wave is pulsed rather than continuous does not alter the frequency of the signal. the new and old frequencies are the same, 5 million/second.

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. A is three times as long as B Frequency and period are reciprocals. if the frequency of one wave is one-third as large as another, then the period of the wave will be three times longer than the other.

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

C. Frequency Frequency is the reciprocal of period. Reciprocals are related in two ways: -as one increases, the other decreases. -when they are multiplied together, the result is unity. For example, a wave with a period of one-hundredth of a second has a frequency of 100 per second or 100 Hz.

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

C. Remains the same Certain parameters of a wave change as the wave travels through the body. However, the period and the frequency of a wave typically remain constant as a sound wave propagates.

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

False. The sonographer cannot adjust the period (or frequency) of a wave produced by a basic transducer. Think of striking a key on a piano. The frequency of sound created by striking a single key is constant. If the sound beam's frequency and period are not suited for the particular type of imaging, the sonographer must select a new transducer with a different frequency.

true or 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. the period of a wave is a characteristic of each individual cycle in the wave. the period of a wave (as well as frequency and wavelength) remains unchanged, whether the wave is continuous or pulsed.

true or false? waves in the ultrasound range behave in the same general manner as sound waves that are audible.

True. the primary difference between audible and ultrasonic waves is that humans can hear audible waves. a wave's behavior or adherence to physical laws and principles is generally the same, regardless of whether it can be heard by humans.

true or false? if the periods of two waves are the same, then the frequencies of the waves must also be the same.

True. frequency and period are reciprocals. when the periods of two waves are identical, the frequencies of the waves must also be identical.