Anti-node

The opposite of a node. When standing waves occur, there are positions in space relative to the wave, called nodes, at which there is no movement at all. The wave interferes with itself to create this instance of opposition (e.g., a wave reflecting off of a wall and back into its own path). Nodes are spaced one-half wavelength apart. On either side of a node is a vibrating antinode. The antinodes alternate in the direction of the wave’s displacement so that the wave at any instant resembles a graph of a sine wave. On a guitar string the nodes are the places on the string that best produce harmonics – particularly at the 12th fret. Touching the antinodes damps the sound.