Standing waves are harmonic waves with equal amplitude, wavelength, and frequency that are moving in opposite directions. They have a phase constant of 0. Standing waves have nodes where the amplitude is 0 and antinodes where the amplitude is at a maximum of 2A. The distance between nodes is half the wavelength, as is the distance between antinodes. An example problem calculates the length of a water pipe with a standing wave pattern by determining the wavelength from the given frequency and speed, and using the node and antinode spacing to relate the length to the wavelength.