Which of the following describes how many cycles occur in one second?

Frequency is the term that describes how many cycles occur in one second. In the context of ultrasound, frequency relates to the number of sound wave cycles produced per second, which is measured in hertz (Hz). Higher frequencies result in better resolution images but lower penetration in tissues, while lower frequencies penetrate deeper but provide less detail.

Each sound wave in ultrasound completes its cycle consisting of compression and rarefaction. The more cycles that occur in one second, the higher the frequency. This concept is crucial in sonography since the choice of frequency can significantly impact the quality and diagnostic value of the ultrasound images obtained.

Other terms mentioned, such as amplitude, period, and speed, refer to different aspects of sound waves. Amplitude denotes the strength or intensity of the sound wave, period is the duration of time taken for one complete cycle to pass, and speed indicates how fast the sound waves travel through a medium. Understanding the distinction between these terms is essential for grasping the foundational principles of ultrasound physics.