Colour & the Spectrum

Prisms, rainbows and blue skies

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• White light is a mix of colours. Colour corresponds to wavelength (from about 400 to 700 nm).
• Dispersion: violet bends more than red, which makes prisms and rainbows.
• Rayleigh scattering (proportional to 1/λ⁴) makes the sky blue and sunsets red.

Steps

1. Newton’s prism
2. Colour is wavelength
3. Which bends most?
4. Rainbows
5. Frequency of green
6. Why is the sky blue?