Light waves are known to behave in one of three ways when they reach the boundary of a medium. That is, the end of one medium and/or the beginning of another. They are either reflected, refracted, or diffracted.
- Diffraction is the phenomenon in which a wave changes direction as it bends around an object in its path or passes through an opening.
- Reflection occurs when a wave comes into contact with a surface, bounces off the surface, and is redirected back into its original medium.
- Refraction is the change in direction a wave undergoes as it passes from one physical medium into another. For example, the direction change when a wave passes from water to air.
These phenomena are not unique to visible light waves. In fact, they can be observed for any wave, including sound waves, water waves, or any wave in the electromagnetic spectrum. However, this blog will focus on the wonders of diffraction of visible light waves.
Light Diffraction is a complex topic, but at Rainbow Symphony, we take great pride in being a gateway to the joys of science for learners at all levels. We’ll take you step-by-step through the basics and show you how you can do your own fun experiments and learn the science of diffraction.
Let’s start with Huygen’s Principle. Christiaan Huygens was a brilliant Dutch physicist, mathematician, inventor, and astronomer, known especially for his contributions to optics and mechanics. The explanations for all three phenomena of light wave behavior are rooted in Huygen’s principle, which states that every point on a wavefront is a source of wavelets, which spread forward at the same speed.
What is Visible Light?
All electromagnetic waves are light, but only light from a certain section of the electromagnetic spectrum is visible to the human eye. Electromagnetic radiation with a wavelength between 380 nm and 760 nm is visible to the human eye. This range is referred to as the visible light spectrum. On the electromagnetic spectrum, the visible light spectrum falls between infrared and ultraviolet waves. The visible effects of diffraction are most pronounced when the length of the opening through which the wave is passing is close to the light’s wavelength.
Examples of Light Diffraction in Nature
Examples of light diffraction can be seen in nature every day! Take, for instance, a cloud’s ‘silver lining’. This visual effect is a result of sunlight bending around the edge of the cloud. The various colors sometimes observed in clouds is another example of light being diffracted, this time by the clouds water droplets. This is called cloud iridescence and is most often observed in cirrocumulus, altocumulus, lenticular, and cirrus clouds. The different colors illustrate how waves of different wavelengths are diffracted differently and ‘scattered’.
Another great example of light diffraction in nature are the rings of light (corona) observed around the sun and other celestial bodies. This is caused by light wave diffraction by small particles in the atmosphere. Even the sky’s apparent blue color, is an example of light diffraction at work. When sunlight hits the earth’s atmosphere, colors of longer wavelengths simply pass through. However, blue, which has a relatively short wavelength, diffracts and scatters upon collision with the atmosphere’s molecules.
You can observe light’s color spectrum by viewing a light source through a diffraction grating in a dark room. A diffraction grating is used to separate light into its constituent colors. It is an arrangement of a large number of equidistant parallel narrow scratches of equal width which are separated by equal opaque sections.
Just as Huygen’s principle states, when a light wave comes in contact with a diffraction grating, the light disperses, forming many point sources with their centers at each slit. Constructive and destructive interference between the ‘new’ light waves occur where their valleys and peaks meet or oppose each other, respectively.
Constructive interference occurs in different directions for different colors due to the differing wavelengths of the colors that make up the visible spectrum. Based on this, we can point a diffraction grating at a white light source and view the different colors in the spectrum.
Shop Our Store Today
Explore the selection of fun products at the Rainbow Symphony store to continue your exploration of light diffraction, including our diffraction glasses and rainbow suncatchers. We also carry three types of diffraction grating slides: the double axis 13,500 line/in diffraction grating slide, the linear 1000 line/mm diffraction grating slide, and the linear 500 line/mm diffraction grating slide.
Contact our team at Rainbow Symphony today for help adding splashes of color to your life and turning experiences from ordinary to extraordinary. Also, keep checking our blog for stimulating discussions on all things relating to light and color.