What is color and how is it created?

What is color and how is it created?

What is color and how is it created?

Why is a tomato red, for example?

In fact, there is no color in nature, but only electromagnetic radiation. Their visible proportion is referred to as light and lies in the wavelength range from about 400 to 750 nanometers. Colour is a subjective impression. It arises when our visual system processes the sense irritation, which is triggered by light of different wavelengths on the retina of the eye.

The sum of all wavelengths present in the light of the sun mixes to the impression of white light. The different colors of objects are mainly due to two phenomena: on the one hand, to the transmission (emission) and on the other hand to the reflection of light.

Colours we perceive with certain sensory cells on the retina, the so-called pin. Of these, there are three types that each have their maximum sensitivity in the areas of red, green or Blue.

Depending on the frequency, the light striking the retina causes an excitation of the different types of pin. The combination of the excitations leads to a specific color impression after processing by the downstream nerve cells and through the brain.

Some objects emit light, such as stars or annealing metal. Depending on the material and temperature, they can radiate in different colors.

In the case of non-self-glowing bodies, the color is “expired” by being irradiated by light. Some parts of the light are then reflected by the irradiated bodies, others are absorbed. Which proportions are in each case depends on the chemical properties of the material. During absorption, the electrons in the irradiated objects are excited by light of certain wavelengths and emit the energy in the form of heat or other non-visible electromagnetic radiation. The color impression thus arises only from the portion of the light which is reflected.

In the tomato, the red colour is caused by the red dye lycopene, which belongs to the carotenoids. This absorbs the green part of the light. The remaining reflected parts meet the retina and our visual system processes the stimulus to the sense impression red.

The question was answered by Dr. Dirk Schanzenbach, Institute of Chemistry at the University of Potsdam.

https://www.wissenschaft-im-dialog.de/projekte/wieso/artikel/ Beitrag/was-ist-color-und-wie-entstand-sie-warum-ist-for example-one-tomate-red/