What Is Color Spectrum Definition Wavelength Order and Examples
What Is Spectrum?
Before understanding the colour spectrum, let us try to understand what is a spectrum? A spectrum is an array of certain elements that have been arranged together in an order of increasing wavelength.
Now, a colour spectrum is an array of 7 colours namely VIBGYOR, arranged in an order of increasing frequencies. The phenomenon was first observed by the profound scientist, Isaac Newton. He observed a white beam of light as it passed through a glass prism. To his surprise, the light from the other side was split into 7 different colour spectrum wavelengths. He studied the phenomenon further before he brought it to the notice of the public in 1665.
Only after this, people started to believe that white light is composed of 7 different colour spectrum wavelengths, namely Violet, Indigo, Blue, Green, Yellow, Orange and Red. This led to the conclusion that " whenever light passes through a medium which is capable of absorbing and reflecting light, spectrum formation is observed".
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What Causes the Spectrum? Let's Dive Deeper!
Light has a characteristic property, called the wavelength of light. The wavelength of light differs from colour to colour. Each colour has a specific wavelength. The spectrum lies in the range of "Visible Spectrum" from wavelengths 700 Nm to 300 Nm. The visible spectrum is merely a small part of the vast electromagnetic spectrum. All the ranges of wavelengths are not visible to the human eye. The human eye can see the wavelengths only between 300 and 700 Newton Meter.
Proof of Newtonian Theory of Spectrum
No theory in Science is acceptable, without optimal proof that validates it. For this, Newton provided excellent proof. He took a wheel that consisted of multiple colours, something like this:
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Then, he rotated the wheel at an excessively high pace. As the speed of the wheel increased, all the colours appeared to merge into a single beam of white light. This merging of colours proved that white light is made of 7 different colours and when all these 7 colours merged, they formed a monochromatic white light. Through this simple experiment, Sir Isaac Newton managed to prove his theory of the spectral nature of light.
Some Interesting Facts of the Spectrum
What is colour? To a common man, the word colour would just mean whatever we see in our surroundings. However, in Class 10 Chemistry Colour Spectrum, we understand the scientific point of view and conclude that the meaning of "colour" is completely different. From the Science perspective, an object has a colour when it absorbs all the wavelengths except one particular wavelength. The wavelength which the object is unable to absorb is reflected back and hence, our eyes can perceive the colour of the object. Objects appear to be colourful only because of the phenomenon of reflection and absorption.
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So the colours you see above are just a result of the phenomenons of reflection and absorption! Sounds interesting, isn't it?
Phenomenons Around Us Based on Spectrum Formation of Light
Rainbow: As kids, all of us would have been extremely fascinated by rainbows. Have you ever pondered upon the science of rainbows? Rainbows are also a result of the scattering of light into its constituent colours. As we saw earlier, when a white beam of light is passed through a glass prism, it scatters into its constituent colours. In the case of rainbow formation, tiny droplets in the atmosphere act as little prisms. As the light passes through these water droplets, the light undergoes total internal reflection. Due to this, the white light splits into 7 different colours and forms a beautiful rainbow in the sky.
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The Colour Effect on a CD: Have you ever observed a CD? If you've keenly observed it, you'd have surely noticed how it reflects light and produces a multi-coloured effect. This is another result of the scattering of light into its constituent colour spectrum wavelengths. The CD is smooth and shiny, it has a tiny gap in between layers which acts as the reflective surface, hence causing the colour spectrum effect. If you haven't observed this effect, you should quickly grab a CD and take a look at it!
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Colour of the Sky: What do you think is the colour of the sky? Blue right? Most of us think that the sky is blue. However, the sky isn't coloured, it is colourless. The blue shade is because of the phenomenon of scattering of light. Blue light has the shortest wavelength and hence it gets scattered easily. Since blue light scatters more than all the other colours, it is the most prominent and therefore the sky appears to be blue.
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FAQs on Color Spectrum and Visible Light in Chemistry
1. What is the color spectrum in chemistry?
The color spectrum in chemistry is the range of colors produced when white light is separated into its component wavelengths, typically from violet to red. In chemical studies, the color spectrum is important because it helps explain how substances interact with light.
- The visible spectrum ranges from about 400 nm (violet) to 700 nm (red).
- Colors are observed when atoms or molecules absorb specific wavelengths and reflect or emit others.
- This principle is used in spectroscopy to identify elements and compounds.
2. What are the colors of the visible light spectrum in order?
The colors of the visible light spectrum in order of increasing wavelength are violet, indigo, blue, green, yellow, orange, and red. These colors correspond to specific wavelength ranges.
- Violet: ~400–450 nm
- Blue: ~450–495 nm
- Green: ~495–570 nm
- Yellow: ~570–590 nm
- Orange: ~590–620 nm
- Red: ~620–700 nm
3. Why do different elements produce different colors in a flame test?
Different elements produce different flame colors because their electrons emit specific wavelengths of light when they return to lower energy levels. In a flame test, heat excites electrons to higher energy states.
- When electrons fall back, they release energy as light.
- The wavelength of emitted light depends on the element’s unique energy level spacing.
- For example, sodium produces a bright yellow flame, while potassium gives a lilac flame.
4. What is the difference between emission spectrum and absorption spectrum?
An emission spectrum shows the wavelengths emitted by an excited atom, while an absorption spectrum shows the wavelengths absorbed from continuous light. Both are related to electron transitions.
- Emission spectrum: bright lines on a dark background.
- Absorption spectrum: dark lines on a continuous background.
- Both correspond to specific energy differences between electron levels.
5. How does wavelength relate to color in the visible spectrum?
Color in the visible spectrum is directly determined by the wavelength of light, with shorter wavelengths appearing violet and longer wavelengths appearing red. The relationship follows electromagnetic wave behavior.
- Short wavelength (~400 nm) → higher energy → violet.
- Long wavelength (~700 nm) → lower energy → red.
- Energy is inversely proportional to wavelength by E = hc/λ.
6. What is the formula for calculating the energy of light in the color spectrum?
The energy of light in the color spectrum is calculated using the formula E = hc/λ. This equation relates energy to wavelength.
- E = energy (J)
- h = Planck’s constant (6.626 × 10-34 J·s)
- c = speed of light (3.00 × 108 m/s)
- λ = wavelength (m)
7. Why are transition metal compounds often colored?
Transition metal compounds are often colored because of d–d electronic transitions within partially filled d-orbitals. When light hits the compound:
- Electrons absorb specific wavelengths.
- They move between split d-orbitals in a ligand field.
- The remaining transmitted or reflected light gives the observed color.
8. How does a spectroscope separate the color spectrum?
A spectroscope separates the color spectrum by dispersing light into its component wavelengths using a prism or diffraction grating. The device works based on wavelength-dependent refraction or interference.
- Light enters through a narrow slit.
- A prism bends different wavelengths by different amounts.
- A diffraction grating separates light by constructive interference.
9. What causes the color of a solution in chemistry?
The color of a solution in chemistry is caused by the selective absorption of certain wavelengths of visible light by dissolved species. The observed color is the complementary color of the absorbed light.
- If red light is absorbed, the solution may appear green.
- Color often arises from electronic transitions in ions or molecules.
- Concentration affects intensity according to the Beer–Lambert law: A = εlc.
10. What is the difference between visible spectrum and electromagnetic spectrum?
The visible spectrum is the small portion of the electromagnetic spectrum that human eyes can detect, ranging from about 400–700 nm. The electromagnetic spectrum includes all types of electromagnetic radiation.
- Radio waves (long wavelength)
- Microwaves
- Infrared
- Visible light
- Ultraviolet
- X-rays
- Gamma rays (short wavelength)
