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The Colourful World of Optics: Exploring Rainbow Formation and Colour Mixing

In the vast realm of optics, the interplay of light and matter creates a mesmerising tapestry of colours that captivates our senses. From the enchanting arcs of rainbows to the subtle nuances of colour mixing, the world of optics unfolds like a vibrant canvas. In this blog post, we’ll delve into the science behind rainbow formation and the intriguing phenomenon of colour mixing, shedding light on the captivating intricacies that make our world so visually stunning.

Understanding Rainbow Formation:

Rainbows, those ethereal arches of colour that grace the sky after a refreshing rainfall, are a breathtaking manifestation of optical phenomena. To unravel the mystery behind rainbow formation, we need to understand the basic principles of light refraction and dispersion.

When sunlight interacts with raindrops suspended in the atmosphere, each raindrop acts as a tiny prism. As sunlight enters the raindrop, it undergoes both reflection and refraction. The light is refracted, or bent, as it enters the raindrop and is then reflected off the inner surface of the droplet. Upon exiting the raindrop, the light is refracted again. This intricate dance of refraction and reflection results in the separation of sunlight into its constituent colours, creating the iconic spectrum of a rainbow.

The sequence of colours in a rainbow—red, orange, yellow, green, blue, indigo, and violet—is a result of the varying wavelengths of light. Each colour corresponds to a specific wavelength, with red having the longest wavelength and violet the shortest.

The Art of Colour Mixing:

While rainbows showcase the natural separation of colours, the world around us often presents a mesmerising blend of hues through the phenomenon of colour mixing. Colour mixing can be categorised into two primary methods: additive and subtractive.

Additive Colour Mixing:

Additive colour mixing involves combining different colours of light. This is the principle behind the vibrant displays of our digital screens. The primary colours in additive mixing are red, green, and blue—commonly known as RGB. By varying the intensity of these colours, a full spectrum of hues can be achieved. Additive colour mixing is prevalent in technologies like television screens, computer monitors, and LED displays.

Subtractive Colour Mixing:

Subtractive colour mixing, on the other hand, occurs when combining pigments or dyes. The primary colours in subtractive mixing are cyan, magenta, and yellow—often abbreviated as CMY. When these colours are mixed, they absorb (subtract) certain wavelengths of light, resulting in the perception of different colours. Subtractive colour mixing is fundamental in the world of art, where painters blend pigments to create an extensive palette.


The world of optics is a captivating realm where science and beauty converge. From the celestial arcs of rainbows to the intricate artistry of colour mixing, the study of light and colour opens our eyes to the wonders that surround us. Whether gazing at a rainbow in the sky or marvelling at the seamless blending of colours on a canvas, the colourful world of optics continues to inspire awe and curiosity, inviting us to explore the fascinating interplay of light and colour.

Also read: Sound Waves: The Science Behind How We Hear

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