Why do rainbows have so many colours?

In one line

The rule

When white light passes through water drops in the air, it bends, splits, and reflects, forming a rainbow of many colors.

Let's understand it simply

Imagine sunlight as a mix of all colors, like a box of crayons mixed together. Normally, we see sunlight as white. But when it rains and the sun shines, each raindrop acts like a tiny glass prism. When sunlight enters a raindrop, it bends (this is called refraction), splits into different colors, bounces inside the drop (reflection), and bends again as it comes out. Each color bends by a different amount, so they spread out and form a rainbow.

How it works

1. Sunlight hits a raindrop in the sky.
2. The light bends (refracts) as it enters the drop.
3. Inside the drop, the light splits into many colors.
4. The light reflects off the back of the drop.
5. As it leaves the drop, it bends again.
6. Each color comes out at a slightly different angle, so we see them spread out as a rainbow.

The story behind it

The first scientific explanation of rainbows was given by Isaac Newton in the 17th century. He used a glass prism to show that white light is made of many colors. Before that, people saw rainbows as magic or signs from the gods. Newton's work helped us understand that rainbows are just light and water working together.

Where you see it in real life

• After rain, when the sun comes out → Sunlight passes through leftover raindrops, making a rainbow.
• Spraying water from a pipe in sunlight → Tiny water drops split sunlight, creating a mini rainbow.
• Dew on grass in the morning → Sunlight can make small rainbows on the grass.
• Mist from a waterfall → Water droplets in the air split sunlight into colors.
• Soap bubbles → Thin layers of water bend light, showing rainbow colors.

Why it matters

• Helps us understand how light works and why we see colors.
• Used in making prisms and lenses for glasses and cameras.
• Shows the science behind natural beauty, making us curious about the world.
• Explains why we see different colors in oil spills or CDs (they also split light).

Common mistakes

• Thinking a rainbow is just painted in the sky — it's made by light splitting.
• Believing rainbows only have 7 colors — actually, there are many shades, but we name 7 main ones.
• Thinking you can touch or reach the end of a rainbow — it's an optical effect, not a real object.

Remember it

A rainbow is sunlight split into colors by raindrops, like a prism in the sky.