10/11/2022
Why is Water Colourless?
I'm some of us have asked this question before, almost everything in existence has a colour. For example, milk is white, lemonade is cloudy, orange juice is orange. Pretty much everything you drink or eat has some color. Then why is that you can see through a glass full of water?
The reason is simple, it's due to reflection of light.
You must already know that white light is made up of several colors (red, orange, yellow, green, blue, indigo and violet), and that anything solid, liquid or gas is made up of tiny particles.
Now when light falls on these particles, they absorb some colors from the light and while some that didn't get absorbed is reflected.
The reflected colour is the one that reaches our eyes. So, the thing therefore appears to be of that color which is reflected back.
For example when you look at orange juice, all colors from the light are absorbed except orange color. Orange color is reflected back and reaches our eyes and therefore the juice looks orange.
Water is colorless and transparent because all except a tiny bit of blue (for pure water) are reflected back. Since water reflects all colors together it looks colorless.
BUT WHY DO SEA WATER LOOK BLUE?
The ocean looks blue because red, orange and yellow (long wavelength light) are absorbed more strongly by water than is blue (short wavelength light). So when white light from the sun enters the ocean, it is mostly the blue that gets reflected. Same reason to why the sky is blue.
This phenomenon is called,"RAYLEIGH SCATTERING".