In which unit are wavelengths typically expressed?

Wavelengths are typically expressed in meters because wavelength is defined as the distance over which a wave's shape repeats. It represents the physical length of one cycle of the wave and is fundamentally linked to the wave's frequency and the speed of light in a vacuum. This relationship is captured through the formula: wavelength equals the speed of light divided by frequency. Since wavelengths involve a spatial measurement, meters are the appropriate unit for expressing this value, making it a standard in physics and engineering for characterizing wave phenomena, including electromagnetic waves and sound waves.

Other units listed, such as seconds, hertz, and decibels, relate to different properties of waves. Seconds pertains to time, hertz is a unit of frequency representing cycles per second, and decibels measure sound intensity or power level. These units are important in their respective domains but do not represent the physical length of a wavelength.