Rami Arieli: "The Laser Adventure" Chapter 1.1 page 2

Wave Description
A wave can be described in two standard forms:

1. Displacement as a function of space when time is held constant.
2. Displacement as a function of time at a specific place in space.

1. Displacement as a function of space, when time is "frozen" (held constant), as described in figure 1.1. In this description, the minimum distance between two adjacent points with the same phase⁽³⁾ is wavelength (l). Note that the horizontal (x) axis is space coordinate !

 Fig 1.1: Displacement as a function of space coordinate (at fixed time)

A = Amplitude = Maximum displacement from equilibrium.
2. Displacement as a function of time, in a specific place in space, as described in figure 1.2. In this description, the minimum distance between two adjacent points with the same phase is period (T). Note that the horizontal (x) axis is time coordinate !

Figure 1.2: Displacement as a function of time (at a fixed point in space)

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