Huygens’ Principle plays a central role in defining and understanding wavefronts in wave theory. A wavefront is an imaginary surface connecting points of a wave that are in the same phase — for example, the crest of a water wave or the peak of a light wave.
According to Huygens’ Principle, every point on a wavefront acts as a source of secondary wavelets, which spread out in all directions with the same speed as the original wave. The new wavefront at a later time is the tangent surface to all these secondary wavelets.
This idea allows us to:
- Visualize the shape and direction of wave propagation.
- Explain how wavefronts move through different media.
- Understand how plane waves and spherical waves evolve.
- Predict how light bends (refracts), reflects, or diffracts when encountering obstacles or interfaces.
In essence, Huygens’ Principle treats wavefronts not just as passive surfaces but as dynamic structures that actively generate future wavefronts, making it a foundational tool for analyzing and predicting wave behavior in various physical situations.