Introduction
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.
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.
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:
Combination 1 - LIVING CORAL #FC766AFF & PACIFIC COAST #5B84B1FF
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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. From a physics perspective, what is colour?
In physics, colour is the characteristic of visible light that is determined by its wavelength or frequency. The human eye can perceive a narrow band of the electromagnetic spectrum, known as the visible spectrum. Each specific wavelength within this spectrum is interpreted by our brain as a different colour, ranging from violet (shortest wavelength) to red (longest wavelength).
2. How do we perceive the colour of an object like a green leaf?
We perceive an object's colour based on the light it reflects. When white light (containing all colours) shines on a green leaf, the chlorophyll pigments in the leaf absorb most wavelengths but reflect the green wavelengths. This reflected green light enters our eyes, stimulating the cone cells in our retina, which then send a signal to the brain that we interpret as the colour green.
3. What is the importance of light for colour perception?
Sufficient light is essential for colour perception. Our eyes have two main types of photoreceptor cells: rods and cones. Rods function in low light but cannot distinguish colours, which is why we see in shades of grey in dim light. Cones are responsible for colour vision but require brighter light to be activated. Therefore, without adequate light intensity, we cannot perceive colours.
4. What is the phenomenon of dispersion and what is its most common example?
Dispersion is the splitting of white light into its seven constituent colours when it passes through a transparent medium like a glass prism. This happens because the speed of light in the medium, and thus the angle of refraction, varies slightly with its wavelength. The most common natural example of dispersion is the formation of a rainbow, where sunlight is dispersed by water droplets in the atmosphere.
5. Why does the sky appear blue on a clear day?
The sky appears blue due to a phenomenon called Rayleigh scattering. As sunlight enters the Earth's atmosphere, it is scattered in all directions by gas molecules and other small particles. Shorter wavelengths of light (like blue and violet) are scattered more effectively than longer wavelengths (like red and orange). Since our eyes are more sensitive to blue light than violet, the sky appears blue to us.
6. What is the difference between additive and subtractive colours?
The primary difference lies in how colours are created:
- Additive colours involve mixing light. The primary colours are Red, Green, and Blue (RGB). When all three are mixed, they produce white light. This is used in digital screens like televisions and monitors.
- Subtractive colours involve mixing pigments, like paint or ink, which absorb (or subtract) certain wavelengths of light. The primary colours are Cyan, Magenta, and Yellow (CMY). Mixing them absorbs more light, and their combination theoretically produces black. This is used in printing.
7. In the context of physics, are white and black considered colours?
In physics, white and black are not considered colours in the same way as red or blue, which correspond to specific wavelengths. Instead:
- White is perceived when an object reflects all wavelengths of the visible spectrum equally, or when all primary colours of light are combined.
- Black is perceived when an object absorbs all wavelengths of the visible spectrum, reflecting no light back to the eye. It is essentially the absence of light.
8. Why do sunsets and sunrises often appear red or orange?
During sunrise and sunset, the sun is lower on the horizon, and its light must travel through a greater thickness of the Earth's atmosphere to reach our eyes. This longer path causes most of the shorter-wavelength blue and violet light to be scattered away from our line of sight. Consequently, the longer wavelengths of red, orange, and yellow are the ones that pass through directly, creating the warm colours we see.
