A triangle of glass - makes visible what is hidden in the white light

A triangle of glass - makes visible what is hidden in the white light

Visible, white light contains all colors ?

A prism - a triangle made of glass - makes visible what is hidden in white light.

If a narrow, neutral-white beam of light is directed onto a prism made of glass or transparent plastic, the beam passes through the prism and exits on an opposite side.
In the process, the path of the light beam is "bent" twice. Once when passing from the air into the transparent material of the prism and a second time when exiting the prism.
This refraction is caused by the abrupt increase and again decrease of density on the path of the light beam.
The air surrounding the prism has a lower density than the prism.

Due to the angles which the surfaces of the prism form to each other, the light beam is also fanned out during refraction. We can already see inside the prism, but even more clearly outside the prism, a colored fan, with colors similar to those we know from the rainbow - the spectral colors.
Theoretically, there are an infinite number of spectral colors. However, in our daily dealings with them, we often only talk about a certain, relatively small number of so-called spectral colors.
As a rule, these are seven main colors:

  • Red
  • Orange
  • Yellow
  • Green
  • Blue
  • Indigo 
  • Violet


Colors - a result of perception
In a reversal of the experiment, all colors created in this way can also be recombined to form a white, homogeneous beam of light.
White light contains all colors... or more precisely: white light contains everything that lets us perceive colors.

Light is not a watercolor...
Light is a so-called electromagnetic radiation.
Like any electromagnetic radiation, it has the propagation variant of a wave; it oscillates with a certain frequency and wavelength.
The analogy to sound and acoustics may be helpful here for understanding, although it is not physically correct.
A tone e.g. of a piano produces a sound wave - vibrations of the air particles, which our ear registers and our brain converts or interprets into audible tones.
Long sound waves with low frequency produce low tones, short sound waves with high frequency produce high tones.

Light as an electromagnetic wave does not need air to move through space - space and time are sufficient for it.
But as with acoustic sounds, the frequency and the associated wavelength of light are responsible for our perception.
Here, however, these oscillations of the light are not perceived as tones, but as colors.
Each individual wavelength triggers a very specific color perception or color.

For example, the following picture results for these three colors:

  • Red ≈ 700-630 nm ≈ 430-480 THz 
  • Green ≈ 560-490 nm ≈ 540-610 THz
  • Blue ≈ 490-450 nm ≈ 610-670 THz

These three colors (RGB) are also the colors that common screens and displays work with.
These 3 colors are the minimum needed to be able to mix a white from them as well.
Low frequencies are experienced as red tones, high frequencies as blue-violet.

In contrast to paints, where each further added color makes the result darker and darker until black (subtractive color mixing), it is the other way round with light.
The so-called additive color mixing, as it is given in the superimposition of colored lights, ensures that with each additional color the result becomes brighter and brighter or even white.

Light is a composition
This physical observation clearly shows the qualitative potential and infinite variety of light. Light and its play of colors, brightnesses and contrasts is a composition.

The sun as our natural source of light, provides the best and highest quality light in this sense.
Objects, animals, plants and people, ultimately the entire world surrounding us, unfold their richness of colors and facets only and exclusively due to the quality of light from the sun.

Technically this is described with the color rendering index, the CRI (Color Rendering Index).

  • Sun: CRI100
  • Energy saving lamps: CRI 75-85
  • Soraa LED: CRI 95 - 98

Decide for yourself if you want to give up 20% or more of details, color nuances, gradations of white tones and the color contrast of your surroundings...