Oscillation.
If the system oscillates periodically, it's a wave or defines a wave-like pattern.
So you have transverse waves that oscillate perpendicularly to their direction of travel...like ripples on a pond. And you have longitudinal waves that oscillate aligned to their direction of travel...like a sonic wave.
All waves, transverse and longitudinal, consist of a wave length, where one wave length is one complete oscillation or one cycle. And when the wave continues, it consists of multiple wavelengths, one after the other.
The time it takes for the wave to travel one cycle, on wavelength, is called the period T = L/V; where L is the wavelength and V is the speed of the wave through whatever medium it's traveling in. The reciprocal of the period is called the frequency f = 1/T.
If the system oscillates periodically, it's a wave or defines a wave-like pattern.
So you have transverse waves that oscillate perpendicularly to their direction of travel...like ripples on a pond. And you have longitudinal waves that oscillate aligned to their direction of travel...like a sonic wave.
All waves, transverse and longitudinal, consist of a wave length, where one wave length is one complete oscillation or one cycle. And when the wave continues, it consists of multiple wavelengths, one after the other.
The time it takes for the wave to travel one cycle, on wavelength, is called the period T = L/V; where L is the wavelength and V is the speed of the wave through whatever medium it's traveling in. The reciprocal of the period is called the frequency f = 1/T.
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Depends which waves - most waves are a series of maxima and minima - peaks and troughs or compressions and rarefactions.