1 Reading the notation

Wave physics uses Greek letters for most of its quantities. Here is what each labels.

9 terms

Cover the right column and check you can say what each one means.

λ (lambda): Wavelength, the distance between two matching points on consecutive waves, in metres.
f: Frequency, cycles per second, in hertz (Hz). f = 1/T.
T: Period, seconds for one complete cycle. T = 1/f.
v: Wave speed, in m s⁻¹. v = fλ. Speed is set by the MEDIUM. Frequency is set by the source and never changes at a boundary.
n (refractive index): How much a medium slows light: n = c/v. Larger n = slower = optically denser. In harmonics, n means something else entirely: the harmonic number. Read the context.
θ (theta): An angle, always measured from the NORMAL (the perpendicular), never from the surface.
θ_c: The critical angle, beyond it, total internal reflection occurs. Only when going from dense to less dense.
Path difference: How much further one wave travelled than the other. nλ → constructive; (n + ½)λ → destructive.
Node / antinode: Node = permanently zero displacement. Antinode = maximum displacement. Adjacent nodes are λ/2 apart.

✓

Frequency NEVER changes: it is fixed by the source. Speed changes because the medium changed, and wavelength follows from v = fλ.

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