Today’s Wonder of the Day was inspired by Teresa. Teresa Wonders, “How are prisms created?” Thanks for WONDERing with us, Teresa!

Do you like rainy days? They’re great for staying in with a board game or a good book. For many, the best part of a rainstorm is what sometimes comes after. Have you ever looked up to the sky after heavy rain and seen a bright, colorful rainbow?

If you’ve been WONDERing with us for a while, you might already know that rainbows form when raindrops split white light into the full spectrum of colored light. But did you know you don’t need rain to make a rainbow? That’s right! You can see all the colors of light anytime you want. All you need is a prism.

A prism is a three-dimensional geometric shape made of glass. A prism’s sides are always polygons. Prisms come in many shapes, and they’re named for the shape of their two ends. One of the most common types is the triangular prism.

Sir Isaac Newton was using a triangular prism when he developed his theory of light. Of course, he wasn’t the first person to experiment with prisms. But before Newton, people believed that glass prisms distorted light. When light shone through a prism and made a rainbow, they thought the colors were caused by the glass.

Newton proved that to be untrue. He placed a prism near his window, causing the full spectrum of light to appear on the opposite wall. This is called dispersion—the splitting of white light into all the colors of light.

But then, Newton placed an inverted prism in front of the spectrum of light. This caused the colors of light to come back together to form white light. That’s how Newton learned that white light was made up of the spectrum of colors.

How exactly does a prism work? Inside the glass, the colors of light travel at different speeds. This causes them to bend at different angles. That’s why they come out separately on the other side of the prism, stacked in order from the fastest color (red) to the slowest color (violet).

If you’ve ever seen a rainbow after a storm, you know just how exciting the sight can be. And with a prism, you can study the science behind rainbows and light right in your own home! What else could you discover? Maybe you’ll come up with a light theory of your own.

Standards: NGSS.PS1.A, NGSS.PS4.B, CCRA.R.4, CCRA.L.3, CCRA.L.6, CCRA.R.10, NCAS.A.10, CCRA.R.1, CCRA.R.2, CCRA.W.2, CCRA.W.4, CCRA.W.9, CCRA.L.1, CCRA.L.2, CCRA.SL1.1

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