explain stationary waves?

Stationary wave - combination of two waves moving in opposite directions, each having the same amplitude and frequency. The phenomenon is the result of interference—that is, when waves are superimposed, their energies are either added together or cancelled out. In the case of waves moving in the same direction, interference produces a travelling wave; for oppositely moving waves, interference produces an oscillating wave fixed in space. A vibrating rope tied at one end will produce a standing wave, as shown in the Figure; the wave train, after arriving at the fixed end of the rope, will be reflected back and superimposed on itself as another train of waves in the same plane. Because of interference between the two waves, the resultant amplitude of the two waves will be the sum of their individual amplitudes. Part I of the Figure shows the wave trains B and C coinciding so that standing wave R has twice their amplitude. In part II, 1/8 period later, B and C have each shifted 1/8 wavelength. Part III represents the case 1/8 period still later, when the amplitudes of the component waves B and C are oppositely directed. At all times there are positions along the rope, called nodes, at which there is no movement at all; there the two wave trains are always in opposition. On either side of a node is a vibrating antinode. The antinodes alternate in the direction of displacement so that the rope at any instant resembles a graph of the mathematical function called the sine. Both longitudinal (e.g., sound) waves and transverse (e.g., water) waves can form standing waves. read less

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. In the second case, for waves of equal amplitude traveling in opposing directions, there is on average no net propagation of energy. read less

Stationary waves also called standing waves: Exaple: When a wire is tied on either sides little tightly,create some vibrations in it. the wave due to vibration hits the end point and reflects back and this process will continue for some time.This system of formation of waves are called standing waves. Visit the website for visualizing pictures: http://www.s-cool.co.uk/a-level/physics/progressive-waves/revise-it/standing-waves read less