Which term describes the distance covered by one cycle?

• A. Pulse Length
• B. Cycle Distance
• C. Wavelength
• D. Cycle Duration

Answer: (C)

Wavelength is the distance the wave travels during one complete cycle. In ultrasound, one cycle is from a crest back to the next crest, so the space covered in that single cycle is the wavelength. The wavelength in tissue is determined by the speed of sound in the medium divided by the frequency (λ = c / f). Since the speed of sound in soft tissue is roughly 1540 m/s, higher frequencies produce shorter wavelengths (for example, doubling frequency halves the wavelength). Pulse length refers to how long the pulse lasts in space (which can include multiple cycles), and cycle duration (the period) is the time for one cycle, not a distance. The term describing the distance per cycle is wavelength.