What does frequency measure in a wave?

Frequency is defined as the number of complete cycles, or waves, that pass a specific point in a given period, typically measured in seconds. It is a vital characteristic of waves, particularly in contexts such as sound and electromagnetic waves. A higher frequency indicates that more waves are passing a given point in that time frame, which directly relates to the energy and pitch of sound waves, or the color of light waves.

In contrast, the speed of the wave refers to how fast the wave travels through a medium, while amplitude is the height of the wave, which impacts the energy carried but does not describe the rate at which waves pass. The distance between the crest and trough relates to wavelength, which is different from frequency as it measures the physical distance of one complete wave cycle rather than how many cycles occur in a set timeframe. Therefore, measuring how many waves pass a point in a specific time captures the essence of what frequency represents in wave behavior.