standing wave

In physics, a wave in which the positions of nodes (positions of zero vibration) and antinodes (positions of maximum vibration) do not move. Standing waves result when two similar waves travel in opposite directions through the same space.

For example, when a sound wave is reflected back along its own path, as when a stretched string is plucked, standing waves are formed. In one wave, called the fundamental vibration, a single antinode remains fixed at the centre, with nodes at the two ends. Other waves will also be set up in the string, with nodes at the ends and a number of antinodes along the string. Water and electromagnetic waves can form standing waves in the same way.