Dispersion and Colour

Lab Brief #4

🎯 Your mission

Set it up. Test it. Be amazed.

⚡ The twist

Energy never disappears — it just hides somewhere else.

What you'll learn

A prism separates white light because refractive index varies slightly with wavelength — violet slows most and bends most, red least. An object looks red because it reflects red wavelengths and absorbs the rest, not because it contains red light.

Key words

dispersion
The splitting of white light into its component colours by refraction.
absorption
The taking in of particular wavelengths by a surface, leaving the rest reflected.

Make a hypothesis first

Before you start: which will move faster, and why?

Say your guess out loud — then find out if you were right.

Get ready

🧰 What you need

triangular prism
ray box
white card
coloured filters
coloured objects

Get ready

⚠️ Safety first

Do not use direct sunlight as the source.
Handle the prism by its faces' edges to avoid dropping it.

Step 1 of 4 · Read

Think about what you just learned: say what "dispersion" and "absorption" mean in your own words before you start.

Step 2 of 4 · Do

Split a narrow beam with a prism onto white card and mark the colour order. Then view coloured objects under a red filter and record which appear black, explaining each result in terms of absorption.

Step 3 of 4 · Observe

Record what actually happened, including anything that did not match what you expected.

Step 4 of 4 · Record

Write a conclusion that answers the question this lesson opened with, and state your uncertainty.

Question 1 of 2

In a prism, which colour is refracted most?

How sure are you?😐 maybe

Question 2 of 2

A blue book looks blue because it:

How sure are you?😐 maybe

Mind = blown

🎢 You feel weightless on a roller coaster because you and the seat are falling at the same speed.

Nice work!

You got 0 of 2 right.

Next: The Eye and Correcting Vision All lessons

🎯

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✨ More to explore

🌍 Where you see this in real life: This is why airplanes can fly and why rockets reach space.

🏆 Stretch challenge (try it this week): This week, find one thing in your house that turns one kind of energy into another.

👨‍👩‍👧 For the dinner table: “Show me something at home that uses this kind of energy.”

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