“Stationary waves are the combination of two waves which move in opposite directions having the same amplitude as well as frequency.” It is also known as standing waves. It is the phenomenon which is the outcome of interference that means when the waves are superimposed; their energies are added at the same time or cancelled. When waves move in the same direction, then their interference generates travelling waves. When waves move in opposite directions, then their interference generates an oscillating wave which is fixed in space.
When two progressive waves of similar amplitude, as well as wavelength, travel with a straight line and in the opposite direction which gets superimposed on each other, it leads to the creation of stationary waves.
Suppose the progressive waves of amplitude and wavelength λ travel in the X-axis direction.
1. The form of wave remains stationary.
In some musical instruments such as sitar, violin, guitar etc., a sound produced with it is due to the vibration of the stretched strings. Here, we will see the different modules of vibration of a string which is fixed at both ends.
The sonometer includes a hollow sounding box which is a meter long in length where one end of a thin metallic wire of cross-section is fixed to a hook and the other side is passed over a pulley attached to the weight hanger. Then the wire is stretched by two knife sides let’s say P and Q with the addition of weight on the hanger. The difference between the distances of two knife edges is in the adjustable form for changing the vibration length of the metallic wire.
1. Fundamental frequency
There are many such applications of generating stationary waves, but the easiest and one of the favourites is its use in the musical instruments.