The contrary is the case when the wave-front passes into a medium where its velocity is greater.
Hence the wave-front is flattened, the curvature of the refracted wave being less than that of the original wave of diffusion.
The middle of the wave-front now travels faster than the flanks, and the curvature is increased.
Hence the wave-front is tilted towards the base of the prism, and this tilting is repeated when the wave-front leaves the prism.
With a dense prism, the wave-front of the shorter waves is more tilted towards the base than the wave-front of the longer waves.
|wave front |
The set of points in space reached by a wave or vibration at the same instant as the wave travels through a medium. Wave fronts generally form a continuous line or surface. The lines formed by crests of ripples on a pond, for example, correspond to curved wave fronts.