$sound and light diffraction$

$sound and light diffraction$

In addition, we will see that Huygens’s principle tells us how and where light rays interfere. It is useful not only in describing how light waves propagate but also in explaining the laws of reflection and refraction. Huygens’s principle works for all types of waves, including water waves, sound waves, and light waves. The new wave front is a plane tangent to the wavelets and is where we would expect the wave to be a time t later. We can draw these wavelets at a time t later, so that they have moved a distance s = v t. Each point on the wave front emits a semicircular wave that moves at the propagation speed v. A wave front is the long edge that moves, for example, with the crest or the trough. The new wave front is tangent to all of the wavelets.įigure 1.26 shows how Huygens’s principle is applied. Starting from some known position, Huygens’s principle states that every point on a wave front is a source of wavelets that spread out in the forward direction at the same speed as the wave itself. The Dutch scientist Christiaan Huygens (1629–1695) developed a useful technique for determining in detail how and where waves propagate. The direction of propagation is perpendicular to the wave fronts (or wave crests) and is represented by a ray.

$sound and light diffraction$

The view from above is perhaps more useful in developing concepts about wave optics.įigure 1.25 A transverse wave, such as an electromagnetic light wave, as viewed from above and from the side. The side view would be a graph of the electric or magnetic field. From above, we view the wave fronts (or wave crests) as if we were looking down on ocean waves. A light wave can be imagined to propagate like this, although we do not actually see it wiggling through space. Huygens’s principle is an indispensable tool for this analysis.įigure 1.25 shows how a transverse wave looks as viewed from above and from the side. This is particularly true when the wavelength is not negligible compared to the dimensions of an optical device, such as a slit in the case of diffraction. However, some phenomena require analysis and explanations based on the wave characteristics of light. So far in this chapter, we have been discussing optical phenomena using the ray model of light. Use Huygens’s principle to explain diffraction.Use Huygens’s principle to explain the law of refraction.Use Huygens’s principle to explain the law of reflection.By the end of this section, you will be able to:

$sound and light diffraction$

Sound and light diffraction