Question

How colour is created? why white light contains seven colors? how every object in earth absorb and emit only certain color which we able to see through our eyes?

Answer 1

The explanation is as follows. Light - or more precisely, VISIBLE LIGHT is a very small portion of theELECTROMAGNETIC Spectrum. While the electromagnetic spectrum covers wavelengths between 100 kilometers and 0.01 nanometers translating to the longest radio waves to the shortest gamma rays, only a very small portion between 400 and 700 nanometers is visible light. Visible light, as we are aware, is considered as white light in a band 200 nanometers wide and when we ‘split’ this band - say using a prism - we perceive colours - meaning, light receptors within the eye transmit messages to the brain, which produces the familiar sensations of colour. At this point, we need to remember that colour is only an ILLUSION. There are no colours in light. 400 nm wave appears VIOLET to most of us* 445 nm Indigo 475 nm Blue 510 nm Green 570 nm Yellow 590 nm Orange 650 nm Red *All of us do not see the same colours! So when we see light, we see the entire band of 400-700 nm and it appears white to us, but it is little more complicated than that. In fact, we cannot 'see' light at all. And it is not "white light" really. It is just ‘light’. Only when light 'reflects' off objects, we see the objects and not the light itself. Most objects around us absorb light too. So, when light falls on a leaf of a tree, for instance, the leaf absorbs all the wavelengths except 510 nm which it reflects, and we perceive GREEN colour. When light falls on a flower, it may absorb all the wavelengths except 650 nm which it may reflect, and we see RED. (no pun intended). So the answer to your question is -“ light does not contain any colours; our eyes perceive different colours when the light is split into smaller bands of wavelength and this is why certain objects appears to be of a particular colour”. Hope it answers your question. All the best!