Transparent Water

 Hi everyone! Welcome to my blog where I share my passion for science and nature. Today I want to talk about a fascinating topic: 

Why and how is water transparent?


Water is one of the most common and essential substances on Earth. It covers about 71% of the surface of our planet and makes up about 60% of our body weight. We use it for drinking, cooking, cleaning, bathing, and many other purposes. But have you ever wondered why water is transparent? Why can we see through it and what makes it different from other liquids or solids?


To answer this question, we need to understand some basic concepts about light and how it interacts with matter. Light is a form of an electromagnetic energy with a wide range of wavelengths. However, the range that a human eye can 'see' is very tiny segment, ranging from about 400 nanometres to about 800 nanometres. This narrow range of wavelengths which a human eye is sensible to, is known as 'the visible region' of the electromagnetic radiation.

Electromagnetic Spectrum and Visible range

Two of the most important interactions a material can engage with radiation are absorption and scattering. When light is incident on an object, the portion that is neither absorbed nor is scattered is, usually, transmitted through it to the other side. If a material absorbs any part of the visible region then the material appears coloured to us. The colour, an object looks, is called 'complementary' to the portion of light absorbed.

Colour Combinations

For example, if a material absorbs blue light (around 450 nm), then it will look yellow (around 600 nm) to us. If a material absorbs red light (around 650 nm), then it will look cyan (around 500 nm) to us. And if a material absorbs green light (around 550 nm), then it will look magenta (around 450 nm) to us.


If a material absorbs all the visible range of light, then it 'looks' black to us because there is hardly any visible light left from the object to reach our eyes. If a material does not absorb any part of the visible range of light, then the object either appears colourlessly transparent, when the light is transmitted, or white, when scattered. Water has H2O molecules that do not have the kind of electrons which absorb any portion of the visible range (but have electrons that absorb only in the invisible ultraviolet range) of light and their size is less than 4 angstroms (tenth of a nanometre) with an average intermolecular space of less than 10 angstroms. That is why water appears transparent. Several other liquids, such as benzene, alcohol, chloroform, coco- nut oil, etc also look transparent for this reason.

Even when the size of the non-absorbing constituents is less or more than the wavelength but if the inter space among them or the size of edges made of them is somehow comparable to the wavelength of the visible radiation, then the object just looks white because much of the unabsorbed light is scattered. A piece of chalk, ground glass, smoke, milk, etc, look white for this reason.

So now you know why water is transparent and how it depends on the properties of light and matter. I hope you enjoyed this blog post and learned something new today. If you have any questions or comments, please feel free to leave them below. And don't forget to subscribe to my blog for more interesting topics in science and nature. Thank you for reading and have a great day!

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