Characteristics of Standing Waves
When two identical waves moving in opposite directions interfere, it results in a standing wave. These waves are characterized by the zero displacement locations which are fixed and are called as nodes and locations of maximum displacements called as antinodes.
1) Standing waves can be transverse or longitudinal.
2) The disturbance confined to a particular region between the starting point and reflecting point of the wave.
3) There is no forward motion of the disturbance from one particle to the adjoining particle and so on, beyond this particular region.
4) The total energy associated with a stationary wave is twice the energy of each of incident and reflected wave. As in stationary waves nodes are permanently at rest. So, no energy can be transmitted across then i.e. energy of one region is confined in that region. However, this energy oscillates between elastic potential energy and kinetic energy of particles of the medium.
5) The medium splits up into a number of segments. Each segment is vibrating up and down as a whole.
6) All the particles in one particular segment vibrate in the same phase. Particles in two consecutive segments differ in phase by 180°.
7) All the particles except those at nodes, execute simple harmonic motion about their mean position with the same time period.
8) The amplitude of vibration of particles varies from zero at nodes to maximum at antinodes (2a).
9) All points (except nodes) pass their mean position twice in one time period.
10) Velocity of particles while crossing mean position varies from maximum at antinodes to zero at nodes.
11) In standing waves, if amplitude of component waves is not equal. Resultant amplitude at nodes will be minimum but not zero. Therefore, some energy will pass across nodes and waves will be partially standing.
12) Application of stationary waves:
i) Vibration in stretched string,
ii) Vibration in organ pipes (closed and open),
iii) Kundt’s tube.