Displacementx (m) - distance of a point on a wave from the mid-point
AmplitudeA (m) - maximum distance from the mid-point
Wavelengthλ (m) - length of one whole oscillation
PeriodT (s) - time taken for one full oscillation
Frequencyf (Hz) - number of full oscillations per unit time Frequency = 1 / Time period
Phase - how far a point is along an oscillation
Phase difference (radians or degrees) - how far along an oscillation one point is compared to another, either on the same wave or two different waves. 2π = 360° = one wavelength
Path difference - the no. of wavelengths between two points on a wave or on two different waves. Measured in terms of λ.
A standing wave, also known as a stationary wave is the superposition of two progressive waves with the same wavelength, moving in opposite directions.
Animation of a standing wave (red) created by the superposition of a left traveling (blue) and right traveling (green) wave
The incident wave is reflected off of the closed end (of the string or tube)
The incident and reflected waves superpose
Where the two waves are in-phase (phase diff. of 0, 2π, 4π etc.), total constructive interference occurs, creating anti-nodes.
Where the two waves are out of phase (phase diff. of π, 3π, 5π etc.), total destructive interference occurs, creating nodes (fixed points on the wave which don't oscillate).