Node (physics)

The opposite of a node is an anti-node, a point where the amplitude of the standing wave is at maximum.

These can be made visible by sprinkling sand on the surface, and the intricate patterns of lines resulting are called Chladni figures.

During compression, the molecules of the medium are forced together, resulting in the increased pressure and density.

Occasionally on a guitar, violin, or other stringed instrument, nodes are used to create harmonics.

With the artificial node method, the overtone is louder and the fundamental tone is quieter.

If the finger is placed at the midpoint of the string, the first overtone is heard, which is an octave above the fundamental note which would be played, had the harmonic not been sounded.

When two additional nodes divide the string into thirds, this creates an octave and a perfect fifth (twelfth).

When three additional nodes divide the string into quarters, this creates a double octave.

When four additional nodes divide the string into fifths, this creates a double-octave and a major third (17th).

In two dimensional standing waves, nodes are curves (often straight lines or circles when displayed on simple geometries.)

[3] In chemistry, quantum mechanical waves, or "orbitals", are used to describe the wave-like properties of electrons.

The number and position of these nodes and antinodes give rise to many of the properties of an atom or covalent bond.