Nodes & Antinodes

NODES: points of ZERO displacement in a standing wave — always at rest.

ANTINODES: points of MAXIMUM displacement — oscillate with amplitude 2A.

Nodes and antinodes ALTERNATE along the wave; spacing between consecutive nodes (or antinodes) = λ/2.

Distance from node to NEAREST antinode = λ/4.

For a string FIXED at both ends: ends are nodes. Allowed λ = 2L/n (n = 1, 2, 3, …).

For a tube CLOSED at one end (open at other): closed end is node, open is antinode. Allowed λ = 4L/(2n−1).

For a tube OPEN at both ends: both ends are antinodes. Allowed λ = 2L/n.

Number of nodes & antinodes determines the HARMONIC number.