Wave shoaling and the angular frequency is proportional to its local rate of change, Simplifying to one dimension and cross-differentiating it is now easily seen that the above definitions indicate simply that the rate of change of wavenumber is balanced by the convergence of the frequency along a ray; Assuming stationary conditions (formula_27), this implies that wave crests are conserved and the frequency must remain constant along a wave ray as formula_28. As waves enter shallower waters, the decrease in group velocity caused by the reduction in water depth leads to a reduction in wave length formula_29 because the nondispersive shallow water
A Brief History of Time chapter. Some theories say that light acts like particles even though it really is made of waves; one theory that says this is Planck's quantum hypothesis. A different theory also says that light waves also act like particles; a theory that says this is Heisenberg's uncertainty principle. Light waves have "crests" and "troughs". The highest point of a wave is the crest, and the lowest part of the wave is a trough. Sometimes more than one of these waves can interfere with each other - the crests and the troughs line up. This is called "light interference". When light waves