The terms "frequency" and "wavelength" are used to describe different aspects of waves, whether they are sound waves or light waves. The distinction arises from the nature of these waves and the properties we want to characterize.
Frequency is a measure of how often a wave oscillates or completes a cycle in a given time period. In the case of sound waves, frequency refers to the number of vibrations or cycles of compression and rarefaction that occur per second. It is measured in units called hertz (Hz). When we perceive a higher frequency of sound waves, we generally perceive it as a higher pitch.
On the other hand, wavelength is a measure of the spatial extent of one complete cycle of a wave. It represents the distance between two consecutive points in a wave that are in phase, meaning they are at the same position in their respective cycles. In the context of light waves, wavelength refers to the distance between two successive peaks or troughs of the wave. It is usually measured in units such as meters (m), nanometers (nm), or angstroms (Å). Different wavelengths of light correspond to different colors in the visible spectrum, with shorter wavelengths appearing as violet and longer wavelengths appearing as red.
The choice of terminology reflects the different ways we perceive and interact with sound and light. In the case of sound, our ears detect the pressure variations caused by the compressions and rarefactions of the wave, which we interpret as sound. Frequency is closely linked to the pitch of the sound we hear. In contrast, light is an electromagnetic wave, and our eyes perceive it based on its interactions with specialized cells. The wavelength of light is directly related to the color we perceive.
While both frequency and wavelength are interconnected properties of waves, the choice of terminology for sound and light is based on the specific characteristics and modes of detection associated with each type of wave.