What is the Spectrum of Light?

S4-SA1-0053

Grade Level:

Class 6

Space Technology, EVs, Climate Change, Biotechnology, HealthTech, Robotics, Chemistry, Physics

Definition

What is it?

The spectrum of light is like a colourful band showing all the different colours that make up white light. When white light, like sunlight, passes through a prism or raindrops, it splits into its many colours, from red to violet.

Simple Example

Quick Example

Imagine you have a big thali with different kinds of rotis – atta roti, bajra roti, makki roti, etc. White light is like that whole thali, and the spectrum of light is like seeing each different roti (colour) separately, laid out in a line.

Worked Example

Step-by-Step

Let's see how sunlight splits into its spectrum:

1. **Start with White Light:** Imagine a ray of sunlight (which is white light) entering a glass prism.
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2. **Bending of Light:** When the white light hits the prism, it bends (this is called refraction).
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3. **Different Bending for Different Colours:** Each colour within the white light bends by a slightly different amount. Red light bends the least, and violet light bends the most.
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4. **Separation of Colours:** Because they bend differently, the colours separate from each other.
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5. **Seeing the Spectrum:** When these separated colours come out of the prism and hit a screen, you see a beautiful band of colours: Red, Orange, Yellow, Green, Blue, Indigo, and Violet (VIBGYOR).
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**Answer:** Sunlight splits into its spectrum (VIBGYOR) because different colours of light bend at different angles when passing through a prism.

Why It Matters

Understanding the spectrum helps scientists in Space Technology analyse light from stars and planets, telling us what they are made of. In HealthTech, doctors use different parts of the light spectrum for treatments and scanning. It's also key for developing new display technologies in our mobile phones and TVs, and even understanding how plants grow using different light colours.

Common Mistakes

MISTAKE: Thinking that the colours in the spectrum are added to white light by the prism or rainbow. | CORRECTION: The prism or raindrops only separate the colours that are already present in white light; they don't create new colours.

MISTAKE: Believing that all colours in the spectrum bend by the same amount. | CORRECTION: Different colours bend at different angles. Red light bends the least, and violet light bends the most.

MISTAKE: Forgetting the correct order of colours in the spectrum. | CORRECTION: Remember the acronym VIBGYOR (Violet, Indigo, Blue, Green, Yellow, Orange, Red) from shortest to longest wavelength, or vice-versa.

Practice Questions

Try It Yourself

QUESTION: Which colour of light bends the most when white light passes through a prism? | ANSWER: Violet light

QUESTION: Name the seven colours of the spectrum in order, starting from the colour that bends the least. | ANSWER: Red, Orange, Yellow, Green, Blue, Indigo, Violet (ROYGBIV or VIBGYOR in reverse)

QUESTION: If you mix all the colours of the spectrum together, what colour of light do you get? Explain why. | ANSWER: You get white light. This is because white light is made up of all these colours, and a prism simply separates them. If you combine them again, they form white light.

MCQ

Quick Quiz

What is the correct order of colours in the spectrum from the one that bends the most to the one that bends the least?

Red, Orange, Yellow, Green, Blue, Indigo, Violet

Violet, Indigo, Blue, Green, Yellow, Orange, Red

Green, Yellow, Orange, Red, Violet, Indigo, Blue

Blue, Green, Yellow, Orange, Red, Indigo, Violet

The Correct Answer Is:

Violet light bends the most, and red light bends the least. So, the order from most bent to least bent is Violet, Indigo, Blue, Green, Yellow, Orange, Red (VIBGYOR).

Real World Connection

In the Real World

You see the spectrum of light every time you spot a rainbow after monsoon rains! The tiny water droplets in the air act like mini-prisms, splitting sunlight into its beautiful colours. Scientists at ISRO use spectrographs (instruments that study light spectra) on satellites to understand the composition of planets and stars far away, helping us learn more about the universe.

Key Vocabulary

Key Terms

SPECTRUM: A band of colours formed when white light splits | PRISM: A transparent object, usually glass, that separates white light into its colours | REFRACTION: The bending of light as it passes from one medium to another | VIBGYOR: An acronym for the colours of the visible light spectrum: Violet, Indigo, Blue, Green, Yellow, Orange, Red

What's Next

What to Learn Next

Now that you understand the spectrum, you can explore 'How do we see colours?' This will help you learn about how our eyes detect these different parts of the spectrum and how objects get their colour, building on what you've just learned!