Standing wave

A wave in which all of the energy is trapped within and reflected by specified boundaries. Such waves will have one or more nodes that are fixed, relative to the specified boundaries. A standing wave will consist of equal traveling waves that are moving in opposite directions.

A standing wave does not deliver any energy to a load. For a resonator that vibrates in air (where the energy transfer to the air can be neglected compared to the internal energy storage of the resonator), the waves within the resonator are essentially standing waves.