In our daily life, we have to come across with lots of colours. For example, we see that the color of the sky is blue, the color of the sun’s light is yellow and the color of milk is white. Now, a question comes to our mind that ‘Why do human eye see different colours?’. Before clearly understanding the phenomenon of different colours of light, we have to understand the absorption and reflection of light.

Absorption of light

In the elementary class science, we have studied about absorption of light. Absorption of light means that a particular material absorbs particular wavelengths of light and after absorbing it, it converts it into energy. It means that the energy state of this light wave changes. After the absorption of light, there is a possibility of lots of options but in this case, we just need to know that this energy is retained by the matter. As a result, this particular wavelength of the light is absorbed by this matter and it will never reflect this wavelength of the light.

Reflection of light

The phenomenon of reflection of light is opposite to the absorption of light. It means that when waves of light travelling in the straight line fall on an object, after falling on this object, these waves of light are sent back. This is known as the reflection of light. If these waves of light are fallen on the shiny and polished objects, more waves of light are reflected back. On the other hand, if these waves of light are fallen on the dull or unpolished surface, fewer waves of light are reflected back.

Why do human eyes see different colours?

The human eye sees different colours of light due to the absorption and reflection of light. As we know that white light consists of seven colours. These seven colours of white light are given below;

When light falls on an object or material, this object or material absorbs some wavelengths of light and some wavelengths of the light are reflected back. The wavelengths of the light which are reflected back provide colour to this object or material.

How do we see the red colour?

If the composition of a specific material is such that it absorbs all the wavelengths of the light and reflects the only red wavelength of the light, the colour of this object or material is red.

How do we see yellow colour?

If the composition of the material is such that it reflects the only yellow wavelength of light and absorbs all the other wavelengths of light, the colour of this material is yellow.

How do we see black colour?

If a specific material or object absorbs all the wavelengths of light and it reflects none, the colour of that material will be black.

How do we see the white colour?

If a specific material or object reflects all the wavelengths of light and it absorbs none, the colour of that material will be black.

How do we see the purple colour?

If the composition of a specific material or object is such that it reflects red and blue wavelengths of light and it absorbs all the other wavelengths of light, the colour of that material will be purple. Its reason is that purple colour is the combination of red and blue colours.

Why the colour of a banana is yellow?

We see different shades of colours in banana like green and yellow. Here, we talk about ripe banana whose colour is yellow. The colour of the banana is yellow because it bounces back 570 to 580 nanometers wavelengths of light and it absorbs all the other wavelengths of light. As we know that 570 to 580 nanometers of wavelengths are the wavelengths of yellow colour. That’s why the color of a ripe banana is yellow.