How Colors Work

Project by Mrigank Pawagi, eNovators

Holi - the Festival of Colors

Holi was here, and I am sure everyone loves to play with colors - at least I do! The water-gun with colored water is my favorite!

But have you ever wondered what makes different colors so different? And why do we see those different colors, differently? Well, here's a simple game to understand!

Why do different things have different colors?

Let's say you have a torch - that gives off white light. Do you know what white light is made of?

We can easily know this by passing the light through a glass prism. Switch on the flashlight below to see what happens!

Did you see that! Indeed, white light is made of seven colors - Violet, Indigo, Blue, Green, Yellow, Orange, Red - the ones you see in a rainbow. This splitting of light into a band of its component colors is what is called DISPERSION.

With this knowledge, let's see why, on adding different colors to water, we see it in different colors. Select a color from the given pallet to add it to water, and observe the light that comes out.

Did you notice? When we add red color to the water, the color absorbs all the colors from the white light except red. Only the red part of the white light escapes and reaches our eye - making us perceive the water as RED. The same is true for all other colors.

Mixing Colors

Very often, even when we might not have colors for every single shade, we make new colors by mixing others. This technique is so useful that with just 7 colors, we can make Twenty One different combinations of two colors!

Try mixing the colors by selecting a color from each of the two pallets.

Now you see, if we mix red and yellow, for example, both the red and yellow colors are emitted, while the rest are absorbed. Our eyes see a combination of the 2 colors - and hence we see ORANGE.

Now here's a small quiz for you - you can answer by taking help from the pallets above!


So far we observed how a mixture of a color with water, absorbed certain colors, and the remaining colors reached our eyes.

However, there's another exciting phenomenon, where certain colors are not absorbed, but SCATTERED, while others are not. In this case, both the colors can be seen, but in different ways. Let's see how.

Light is a Wave

First of all, we need to know that light is a wave. It sometimes also behaves like a stream of particles, but for our experiment, it's better to assume the wave nature.

Now, What is a wave? In simple terms, a wave is an oscillating path in which energy can travel. Light can have different kinds of waves, depending on its color. The difference between two successive crests (hills) or troughs (valleys) in the wave is called its WAVELENGTH.

As you can see, different colors have different wavelengths.

Could you notice the difference? It seems very little - and is very little (just tens of nanometers) - yet very significant at the micro-scale!

Scattering of light takes place in heterogenous mixtures - when the crests and troughs of the light-wave bump against the particles in the mixture. Light interacts in this manner only with particles whose size is equal to or greater than it's wavelength.

This is called SCATTERING of light. As you might have guessed, different sized particles can scatter light of different colors.

The scattered colors of light are spread across the mixture and emitted in every direction, while the remaining unscattered colors leave the medium in their straight-line path.

Color Wavelength (nanometers)
Red 670
Orange 605
Yellow 580
Green 535
Blue 480
Indigo 450
Violet 420

Using the slider below, try changing the size of the particles in water. Measures are in nanometers.

1000 nanometers

As you might have guessed, the colors appearing out from left and right, are the SCATTERED colors, while the unscattered colors come out from the fourth side.

Intuitively, this is the exact phenomenon that causes the blue color of the sky, and the reddish color of the sun!


I hope you liked this journey into the colors of Holi. Although the primary purpose was to combine coding with colors, I hope this module could explain some simple phenomenon related to colors, in a fun way.

There are a lot many other phenomena about colors and light - whose significance goes beyond Holi. Here are links to the subjects I mentioned here if you are interested in knowing more.

You can know more about me on my website and my Dojo at eNovators.