In wave terminology, what is the wavelength?

• A. The distance between two adjacent high or low points of a wave.
• B. The height of the wave.
• C. The amplitude of the wave.
• D. The speed of the wave.

Answer: (A)

The wavelength is the distance over which the wave’s pattern repeats as it travels. In practical terms, it equals the distance between two consecutive crests (high points) or two consecutive troughs (low points) along the direction the wave moves. This measures how long one full cycle of the wave lasts in space, typically expressed in meters.

This is different from the height of the wave, which is its amplitude—the maximum vertical displacement from rest. It’s also different from speed, which tells you how fast the wave travels; speed is related to wavelength and frequency by v = λ f. For example, if crests repeat every 2 meters, the wavelength is 2 meters.