Definition:Harmonic Wave/Period

Definition
Let $\phi$ be a harmonic wave expressed as:
 * $\forall x, t \in \R: \map \phi {x, t} = a \map \cos {\omega \paren {x - c t} }$

The period $\tau$ of $\phi$ is the time taken for one complete wavelength of $\phi$ to pass an arbitrary point on the $x$-axis.

Also see

 * Period of Harmonic Wave: this period is shown to be $\dfrac \lambda c$, where $\lambda$ is the wavelength of $\phi$