Physics trivia

Five fun facts about colors

Colors are perceptions present in everything we do and bring with them several curiosities, which can go unnoticed.

When light passes through a transparent prism with an index of refraction greater than that of air, it decomposes.

How about learning a little more about colors ? In this article, we will address some facts that you may not be aware of about colors.

#1 – Object colors

What color are the objects around you? First it is important to know if what you are looking at is a primary or secondary source of light . Primary light sources produce their own light through the excitation of their atoms, thus being able to emit different frequencies according to the energy levels provided by the excitation sources.

Examples of primary sources are:

  • The sun and the other stars;
  • Lighted lamps;
  • bonfires;
  • lasers.

Of the processes of light emission by primary sources, we can highlight some, such as:

  • Thermoluminescence;
  • glowing;
  • Fluorescence;
  • Phosphorescence;
  • Bioluminescence.

Secondary light sources only reflect the light that reaches them. Its color is closely related to the ability of its atoms to absorb or reject certain wavelengths of incident light.

In this way, when we look at a black surface , all wavelengths of incident light have been absorbed by the material that composes it. When we look at a white surface , all these wavelengths are being reflected by its atoms. The origin of this behavior is quantum and is related to the energy levels of atoms:

A sheet of paper may even be white when illuminated by sunlight, but try putting it in a closed room fully lit by red, monochromatic lamps: it would look red.

#2 – Our color perception is not absolute

Ask different people the colors of different objects around you and you will realize that there is no consensus. This is because our sensory organs are slightly different, as is the interpretation of colors , which is done by the brain.

Inside our eyes there are photoreceptor cells specialized in capturing light and transforming it into nerve impulses, which are translated by the brain. These cells are called cones and rods .

Humans have three different types of cones: blue, green, and red light-sensitive cones. Some animals can have up to twelve different cones – in practice, these animals can see a multitude of extra colors!

Driving a silver car can lower your chances of having an accident

According to a study conducted in New Zealand involving around 1000 cars, the chance of a driver who drives a silver car having an automobile accident is up to 50% lower compared to drivers who drive white cars. What is the reason for this difference?

The study could not come up with a completely satisfactory explanation, but there are suggestions that the high reflectivity of metallic colors can increase the visibility of cars on the roads.

#4 – White and black aren’t exactly colors

That’s right! White light is actually a composite of all the colors of the visible spectrum, so when we look at a white reflective surface, it tells us that it reflects all the light that reaches it.

To understand this, just look at the rainbow phenomenon: the sunlight, which is white, reaches the droplet and is dispersed within it. From there, we see all the colors in the visible spectrum being separated because of the refraction of light.

Black, on the other hand, occurs when there is total absence of light, either because there are no light sources, or because the surfaces of objects absorb all wavelengths of incident light.

#5 – We are sources of light (literally)!

Scientists at Kyoto University in Japan have discovered that the human body is capable of emitting light in the visible range of the electromagnetic spectrum . In fact, most living beings can do it, however, the intensity of this light is about 1000 times lower than the lowest levels of light perceptible by our eyes.

All this light comes from biochemical reactions involving free radicals present in the skin. The “brightest” part of our body is the face, possibly because it is the part of the body most exposed to sunlight, which, in turn, is able to excite some fluorescent compounds present in melanin, increasing the body’s production of light. .

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