The problem with indigo and other organic dyes is that it fades away in time because it absorbs energy, instead of reflecting it. In time, bonds break as a result of the damage.
Inorganic dyes like pure iron oxide or rust ochre , however, are lightfast and can last for thousands of years. This is why cave paintings are still visible today! As a conclusion, things do not have color by themselves — only when light energy hits them, we can see colors.
Also, remember our eyes can only see a limited range of colours. But dogs, cats, mice, rats and rabbits have very poor colour vision.
Evolution led bees to adapt ultraviolet vision because flowers leave scatter ultraviolet patterns, allowing the insects to easily identify targets and pollinate. This is what spectrometers are for. Tibi is a science journalist and co-founder of ZME Science.
He writes mainly about emerging tech, physics, climate, and space. In his spare time, Tibi likes to make weird music on his computer and groom felines. Home Other Did you know? What makes things coloured — the physics behind it Have you ever wondered where do colours come from?
May 10, Reading Time: 5 mins read. This way, when light hits matter one or more of the following phenomena happens: reflection and scattering. Most objects reflect light, but some are more reflective than others, like metals. This is directly related to the number of free electrons that are able to pass from atom to atom with ease.
This is how TV and computer screens work. If you look at a screen with a magnifying glass you will be able to see that only these three colours are being used.
For example, red and green lights are used to make our brain perceive the image as yellow. When coloured lights are mixed together, it is called additive mixing. Red, green and blue are the primary colours for additive mixing. If all of these colours of light are shone onto a screen at the same time, you will see white.
This is different when you are mixing paints. Each colour of paint is absorbing certain colours and reflecting others. Each time another colour of paint is mixed in, there are more colours absorbed and less are reflected. The primary colours for adding paints or dyes, such as for a computer printer, are yellow, magenta and cyan.
If you mix all of these colours together, you will absorb all the light and will only see black, because no light will be reflected back to your eyes. You can easily experiment with this. Hold some coloured cellophane in front of your eyes and have a look around. Notice how some colours are changed and others look similar. Figure out which colours are being absorbed. It sometimes takes a long time for new scientific knowledge to become widespread.
For example, many people used to think that dogs could only see in black and white. It is now known that dogs have two kinds of colour receptors that allow them to see yellows and purples. Even though the initial experiment was done in , many people are still unaware that dogs can see some colours.
Ever wonder why fluorescent colours look so bright? It is all due to energy, as explained in the article Light — colour and fluorescence. When you look at a banana, the wavelengths of reflected light determine what color you see. The light waves reflect off the banana's peel and hit the light-sensitive retina at the back of your eye. That's where cones come in. Related: How do our eyes move in perfect synchrony? Cones are one type of photoreceptor, the tiny cells in the retina that respond to light.
Most of us have 6 to 7 million cones, and almost all of them are concentrated on a 0. Not all of these cones are alike. About 64 percent of them respond most strongly to red light, while about a third are set off the most by green light.
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