🌈 Make a Rainbow
Use a glass of water and sunlight to split white light into all the colours of the rainbow — no special equipment needed!
🧰 What you need
🔬 Steps
- 1
On a sunny day, fill a clear glass all the way to the top with water.
- 2
Place it on a windowsill so sunlight shines through it.
💡 This works best in the morning or afternoon when the sun is at an angle, not directly overhead. - 3
Hold a white sheet of paper on the other side — try different distances and angles.
- 4
Move the paper until you see a rainbow of colours appear on it!
💡 If using a torch indoors, shine it through the glass at a low angle onto white paper on a table.
🧠 The Science
White sunlight is actually a mixture of all the colours of the visible spectrum: red, orange, yellow, green, blue, indigo, and violet (ROYGBIV). When light passes from air into water and back into air, it bends — this is called refraction. Different colours bend by slightly different amounts: violet bends the most, red the least. This separates white light into all its component colours, creating a rainbow. The same thing happens in raindrops to make rainbows in the sky after rain!
📚 Related Lessons
- 🌍 Day & Night — Why day turns to night and back again.