Which characteristic of waves is typically measured in hertz (Hz)?

The correct answer is frequency, which refers to the number of cycles of a wave that occur in one second. It is measured in hertz (Hz), with one hertz being equal to one cycle per second. This characteristic is crucial in various applications, including Nondestructive Testing (NDT), as it relates to how rapidly a wave oscillates, thus influencing its behavior and interaction with materials.

Each of the other characteristics, while important, is not measured in hertz. Amplitude describes the height of the wave and is typically measured in units such as volts or pressure, depending on the context. Wavelength signifies the distance between successive peaks of a wave, measured in meters or other units of length. Speed refers to how fast the wave travels through a medium and is typically measured in meters per second. Understanding these differences helps in correctly applying wave principles in testing and analysis scenarios.