Non-selective scattering is a form of light scattering that happens when the particles in a medium, like fog or clouds, are larger than the wavelength of the incident light. In the non-selective scattering of white light, all wavelengths are scattered approximately equally.
Tyndall effect
Tyndall effect is another phenomenon related to scattering, where light is scattered by colloidal particles, causing them to become visible in a transparent medium.
Colloidal particles are small solid particles or liquid droplets that are dispersed within a medium, typically a liquid or a gas.
Refraction occurs when light changes speed and direction as it passes from one transparent medium (like air) to another (like water).
Chromatic dispersion is the phenomenon where light separates into its various colours, each with a slightly different wavelength, which bend at slightly different angles during refraction.
Scattering in raindrops obeys the laws of both reflection and refraction, commonly referred to as Snell’s law. Here are three related descriptions of what causes scattering when visible light strikes a raindrop:
When light of a specific wavelength strikes the surface and enters a raindrop its subsequent path depends upon the point of impact, and the refractive indices of water and air.
When rays of light of a single wavelength strike a raindrop at different points, scattering is primarily determined by the angles at which they enter the droplet.
The interaction between refraction and chromatic dispersion gives rise to the appearance of rainbow colours when parallel white light rays strike various points on the surface of a raindrop.
Random scattering occurs when a material, due to irregularities or imperfections on its surface, reflects or transmits lightrays in various unpredictable directions.
Reflected light may appear hazy or lack detail, or there may be no clear reflection at all.
When light passes through sheets of glass with irregular yet smooth surfaces, random scattering distorts the view of the world beyond, making the image blurry and confused.
A reflection that is free of the effects of random scattering is called a specular reflection. Mirrors generally produce specular reflections.
Diffuse light
Diffuse light is a specific type of random scattering that occurs when light bounces off rough or uneven surfaces.
In these cases, the light scatters in all directions, creating a soft, even glow.
The overall structure and composition of a material can also cause diffuse light.
This happens when light travels through a medium that contains foreign materials, suspended particles, or has an irregular internal structure or variations in density.
Translucent materials containing dissolved substances, however, typically don’t cause random scattering because the particles are too small.
On a microscopic scale, all objects adhere to the law of reflection; however, when surface irregularities are larger than the wavelength of light, the light undergoes scattering leading to diffusion.
Regular scattering happens when light bounces off a smooth, curved surface in a predictable way, creating a clear and undistorted image.
Think about a spoon in a glass of water. The smooth, curved surface of the spoon predictably bends the light, making the spoon appear slightly bent or magnified. This is an example of regular scattering.
Regular scattering often occurs when parallel rays of light hit smooth, transparent objects like raindrops or prisms. In these cases, the light bends (refracts) in a predictable way depending on the angle it hits the object and the materials involved.
Let’s look at two cases of regular scattering in more detail:
When parallel rays of light with a single wavelength strike and enter an object like a raindrop or prism, their path depends on the initial point of impact, the refractive indices of air and water, and the object’s surface properties.
When parallel rays of incident light with a single wavelength meet the curved surface of a transparent medium at various points, the different angles at which they strike the surface and experience deflection mainly determine how they scatter as they exit the medium.