What is light?
As I explained earlier, light is the radiation of electromagnetic waves that have a certain spectrum. Light that we can see or commonly referred to as visible light has a wavelength between 400-700 nanometers. So actually the light that we can see is only a small part of the spectrum of electromagnetic waves.
Well, if so, is there a wavelength of light that the human eye cannot catch but other animals can? Of course there are, for example infra-red and ultra-violet. Scientists have also examined the spectrum of colors that may exist, but cannot be seen by the human eye because of the limitations of nerve nerves in the retina of our eyes.
There are several properties of light that allow us to see the color spectrum. This quality is one of the factors that makes us able to see colors:
Nature 1: Light spreads
The light is a particle and waves that move at a constant speed (C) which is about 300 million meters / second. So far, there are no other particles in the universe that propagate faster than light. Light is the fastest information conveyor known to man today.
Property 2: Light can be reflected.
Light can be reflected based on the shape of the surface of the object that meets light, there are two different interactions. When light meets the surface of a flat object, light will be reflected regularly. Whereas if light meets the surface of a wavy object, light will be reflected diffusely.
Regular reflection images coexist with diffuse reflection
Nature 3: Light can be refracted
The nature of the next light that causes us to see the color spectrum is that light can be refracted. Because light is a wave, we can be sure that light can propagate or spread through a medium. When light spreads through two objects that have different densities, there will be refraction or bending of light.
If light spreads only on the same medium, light will propagate in a straight line. But when it passes through two mediums with different densities, the light will change. Examples like this picture:
The refraction image of light through two different mediums
The pencil looks like it's broken right? Even though it doesn't break but how can it look like that? The answer is because our eyes receive information in the form of visible light. Well, the upper half of the pencil that we see from the light moving in the air, while the bottom of the pencil we see from the light moving through the water.
The bias angle formed between the normal line and this light deflection will be greater if the second medium density is greater than the first medium density. Because light can be refracted, light can also be broken down through a process we commonly call a dispersion process. You can watch the explanation material about light waves here.
Let's say there is white polychromatic light entering the clear glass prism. Polychromatic light is light that carries more than one light wave. For white light like sunlight, light transports all the color spectrum.
When white light is fired into the prism, the resulting refractive light will decompose according to the wavelength of each color. For white light, the resulting light will break down like rainbow colors, namely red, orange, yellow, green, blue, indigo and purple.
Each color spectrum will experience refraction with a different bias angle depending on the wavelength of each color. The difference in deviation or bending of light between these colors is what we call dispersion.