What is "standing wave"

n. A wave form which occurs in a limited, fixed medium in such a way that the reflected wave coincides with the produced wave. A common example is the vibration of the strings on a musical stringed instrument.

n. a wave (as a sound wave in a chamber or an electromagnetic wave in a transmission line) in which the ratio of its instantaneous amplitude at one point to that at any other point does not vary with time [syn: stationary wave]

In physics, a standing wave – also known as a stationary wave – is a wave in a medium in which each point on the axis of the wave has an associated constant amplitude. The locations at which the amplitude is minimum are called nodes, and the locations where the amplitude is maximum are called antinodes.

Standing waves were first discovered by Franz Melde, who coined the term "standing wave" (German: stehende Welle or Stehwelle) around 1860.

This phenomenon can occur because the medium is moving in the opposite direction to the wave, or it can arise in a stationary medium as a result of interference between two waves traveling in opposite directions. The most common cause of standing waves is the phenomenon of resonance, in which standing waves occur inside a resonator due to interference between waves reflected back and forth at the resonator's resonant frequency.

For waves of equal amplitude traveling in opposing directions, there is on average no net propagation of energy.