What does a hertz measure?

A hertz is defined as one cycle per second, making it a unit of frequency. It quantifies how often an event occurs within one second. For example, if a sound wave completes one full oscillation every second, it is said to have a frequency of 1 hertz. This makes the measurement very relevant in various fields such as acoustics and electronics, where understanding the frequency of signals is crucial.

The other options do not accurately represent what a hertz measures. Amplitude per time does not reflect frequency but rather how a wave’s height changes over time. Energy per cycle pertains to the energy associated with one full oscillation of a wave but does not relate directly to frequency itself. Voltage per second would imply a rate of change of voltage over time, which is not the definition of hertz. Hence, the correct answer reflects the fundamental concept of frequency measurement in hertz accurately.