A standing wave is created when two waves of identical frequency and amplitude interfere with each other in a medium, producing both constructive and destructive interference.

Standing waves, often referred to as stationary waves, result from the superposition of two waves traveling in opposite directions. For this phenomenon to occur, the waves must possess the same frequency, wavelength, and amplitude. Standing waves typically form in mediums that are fixed or bounded at both ends, such as a string on a musical instrument or an air column within a wind instrument.

The process of forming a standing wave begins when a wave is introduced into a medium and encounters a boundary that reflects it back. This reflected wave then interferes with the incoming wave. When these two waves meet at precisely the right moment, they interfere constructively, resulting in an increased amplitude and creating a point of maximum displacement known as an antinode. Conversely, if they meet at an unfavorable moment, they will interfere destructively, canceling each other out and forming a point of zero displacement, called a node.

The arrangement of nodes and antinodes gives standing waves their distinctive appearance. Unlike traveling waves, which propagate through a medium, standing waves appear to remain stationary, with the points of maximum (antinodes) and minimum (nodes) displacement fixed in space. This characteristic is why they are referred to as ‘standing’ or ‘stationary’ waves.

The frequency at which a standing wave is established in a medium is determined by the medium’s natural frequencies, or harmonics. These are the frequencies at which the medium naturally vibrates. For instance, in the case of a string, the fundamental frequency (the first harmonic) is the frequency at which the entire length of the string vibrates as a single segment. The second harmonic (the first overtone) occurs when the string vibrates in two segments, and this pattern continues with higher harmonics. When a wave is introduced into the medium at one of these specific frequencies, it resonates with the medium, resulting in the formation of a standing wave.

In summary, the creation of a standing wave involves a complex interplay of wave reflection, interference, and resonance. Although specific conditions are necessary for its formation, when these conditions are met, the outcome is a wave that appears stationary, exhibiting a fixed pattern of nodes and antinodes in space.