Examples of Huygen’s Principle

Christian Huygens (1629-1695), a prominent Dutch physicist, published a dissertation on the wave theory of light in 1678 called Traite de la Lumiere. He stated in this paper that the wavefront of a propagating wave of light conforms to the envelope of spherical wavelets coming from every point on the wavefront at every instant (with the understanding that the wavelets have the same speed as the overall wave). The idea changed the way we think about light and its properties.

In these examples of the Huygens principle, we will understand Huygens principle importance.

Meaning of Huygens principle

Huygens’ principle, also known as the Huygens-Fresnel principle, states that all points of a wavefront of sound in a transmitting medium or light in a vacuum or transparent medium can be considered new sources of wavelets that extend in all directions at a pace determined by their velocities. It is a powerful approach for examining numerous optical phenomena that were proposed by the Dutch mathematician, physicist, and astronomer Christiaan Huygens in 1690. Any point on the wavefront can be considered a source of secondary spherical wavelets that expand out at the speed of light in the forward direction. The tangential surface of all these secondary wavelets is the new wavefront. As a result, it’s a geometrical method.

One of the essential methods for researching various optical phenomena is Huygens. The principle is a way of analysing wave propagation problems in the far-field limit and near-field diffraction and reflection. The following is stated in it:

• Every point on a wavefront is a source of spherical wavelets that expand out at the speed of light in the forward direction

• The sum of these spherical wavelets usually forms the wavefront

• Secondary sources produce wavelets comparable to those produced by the primary source

• Common tangent on the wavelets in the forward direction generally delivers the new wavefront at any given time

Sources under the Huygens principle

Light, according to Huygens, is a wave that propagates through space in the same way that ripples in water or air do in sound. As a result, light from a source usually spreads out in all directions like a wave. A wavefront is a set of points that have travelled a certain distance over a specific time interval. As a result, we can see that the locus of points that light has travelled within a particular time is a sphere from a point source of light.

Thus, under the principle, sources can be of two types: primary and secondary. Following the completion of the primary wavefront formation, each primary wavefront is followed by creating a secondary wavefront. Thus, every point on the wavefront works as a secondary light source, emitting additional wavefronts. So, a light wave propagates over space by generating secondary sources and wavefronts. The wavefronts are always said to be perpendicular to the transverse direction.

Thus, considering that Huygens’ theory was proposed two centuries ago, it adequately describes the wave theory of light phenomena of diffraction, interference, reflection and refraction.

Huygens’ principle importance

Huygens’ principle’s Importance is that the principle applies to all sorts of waves, including water, sound, and light waves. It helps explain the rules of reflection and refraction and describes how light waves propagate. It asserts that all points on a wavefront of sound in a transmitting medium or light in a vacuum or transparent medium can be considered new sources of wavelets that expand in all directions at a pace determined by their velocities. The total of these spherical wavelets usually forms the wavefront. However, this theory leaves open the question of why refraction occurred in the first place. Huygens’ principle aids in predicting and comprehending classical light wave propagation. As a result, the Huygens-Fresnel Principle can explain a broad spectrum of optical phenomena.

Huygens’ principle Examples

The Huygens’ principle is integrated into our day-to-day lives and finds its application everywhere. When an open doorway links two rooms and a sound is created in a distant corner of one of the rooms, the Huygens’ principle is in action. The sound will be heard in the other room as if it came from the doorway. 

In another example, you can say that if a stone is thrown in the pond, a bigger stone tends to create more ripples in the water as compared to smaller ones.  These waves resemble circular rings, which are known as wavefront waves. These wavefronts gradually scatter in all directions. The secondary sources, and the secondary sources of these sources, and so on, propagate these ripples in all directions. 

Conclusion

In these Huygens’ principle notes, we have understood Huygens’ principle, an analysis method that can solve wave propagation problems in the far-field limit, near-field diffraction, and reflection. Light, according to Huygens, is a wave that propagates through space in the same way that ripples in water or air do in sound. Thus, according to the principle, every point on a wavefront is a source of spherical wavelets that expand at the speed of light in the forward direction. We have also discussed the Huygens principle importance, and examples.