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Last updated date: 18th May 2024
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Everything we observe around us has some appearance, some objects have an emerald green colour, some are golden yellow, while some have a classic blue colour, and so on.

Do you know why we experience this distinction? It’s because each of these colours has a particular wavelength in the light spectrum and that the reflection of these fall onto our eyes. So, colour is the wavelength of light on the visible spectrum. 

In this article, we will discuss colour, the colour of rainbow, and colour combinations, etc.

What is Colour? 

Colour is the reflection of the light of any object onto the eye. We can describe colour in terms of hue, lightness, or saturation. In physics, colour is associated more specifically with electromagnetic radiation or EM waves of a certain range of wavelengths visible to the human eye. Radiation of such wavelengths that a human eye can pertain to is that portion of the electromagnetic spectrum, which we commonly call the visible spectrum, viz:  the light.

A colour that forms a band of seven colours is called the spectrum, where spectra mean seven and naturally, we can see this effect as a rainbow during rainy seasons. Now, we will understand the colour of the rainbow.

Colour of Rainbow

We all observe a spectrum of different colours that give a beautiful scenic view to the sky during the rainy season. Do you know what this beautiful scenic view is called? Well! It’s a rainbow. 

A rainbow is a collection of colours where each colour carries its own wavelength and frequency. 

Starting from Violet having the least wavelength and high frequency, then indigo, blue, green, yellow, orange, and red with low frequency and high wavelength.

So, the combination comes as VIBGYOR. Here, VIBGYOR is rainbow colours in order. Now, let’s see the range of these lights on the visible spectrum:

Colour Wheel

Each and every colour present on this planet carries its own existence. We categorize its existence by wavelength and frequency and let's do this part followed by various colour combinations.


Frequency (in TetraHertz)



668 THz to 789 THz

400 to 440


600 THz to 700 THz



606 THz to 668 THz

460 to 500


526 THz to 606 THz

500 to 570


508 THz to 526 THz

570 to 590


484THz to 508 THz

590 to 620


400 THz to 484 THz

620 to 720

Now, we will the wavelength of primary colour wheel in Angstrom:

Primary Colour Wheel

An Angstrom or Å is equivalent to the 1/10,000,000,000 of a meter. The atom-like hydrogen measures approximately one Å. The wavelength of optical light generally ranges from 4500 Å to 7000 Å. Below are the various kinds of light wavelengths and frequency given in Å.


Wavelength (in Å)


4000 Å to 4240 Å


4240 Å – 4912 Å


4912 Å – 5750 Å


5750 Å – 5850 Å


5850 Å – 6470 Å


6470 Å – 7000 Å

Colour Combinations

When two or more colours are combined, we get various combinations that are distinctive in nature. A human eye is the gifted optical lens that can easily distinguish among 1000+ shades of a single colour.

If we talk about a Primary colour wheel, Red, Green, Blue is taken as primary colour combinations. 

Different colours we find in our surroundings like mauve, navy blue, teal colour,  turquoise colour, colour burgundy, coral colour, dark green, light green, crayon colours are all colour combinations.

Now, let’s look at some eye-catching colour combinations for the year 2021 and the colouring of these can be done by using a watercolour:


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Living Coral is a lively, nourishing colour that has a youthful flavour in it. On combining it with the refreshing blue of the Pacific Coast, it elicits images of the ocean floor and a vibrant seabed filled with coral.

Pacific Coast is a deep colour that subtitles the tone of Living Coral. Akin to most shades of blue, there is almost a certain warmth in this colour. This reason serves to bring the peace and energetic vibe of Living Coral.

Combination 2 - Blue #00A4CCFF & Orange #F95700FF

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The classic combination of blue and orange has always been in its higher position over the years, The cool and calming tones of blue emphasize the warmth that orange radiates. This pairing is more often found in nature, it is also meant to be comfy and familiar to the human eye.

From nature to the communication perspective, this colour combination has been used in uncountable posters, adverts, and commercial campaigns, and many more places over the years. 

This combination never dies, in fact, it is an effective method of catching an audience’s eye.

FAQs on Colour

1. State the Necessary Factor For Colour Perception.

Ans: Vision is responsible for the perception of colour. We can see in dim light; however, without being able to distinguish colours. When normal light is present, then only we can distinguish among colours. Light of a given critical intensity is, therefore, necessary for colour perception.

2. How Do We Perceive the Colour of an Object?

Ans: We perceive the colour of the object because of the way we interact with light. The science behind this interaction and the factors that help us determine it are the concerns behind the physics of colour. The physiology of colour involves the response of the eye and the brain to light and the sensory data they produce. The psychology of colour is called upon when the mind processes visual data, compares it with information stored in our memory and then interprets the same as colour.

3. What is the Physics Behind Colour Recognition?

Ans: We can determine colour by frequency and by how these frequencies are combined or mixed, and also when they reach our eye. Light falls on specialized receptor cells, via cones to the back of the eye called the retina and a signal is sent to the brain along a neural pathway called the optic nerve; this is how we receive the colour.

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