Disappearing Coin Trick

Light can behave in some surprising ways. This disappearing coin trick is a great experiment to show one of the surprising ways. If you don't know how this trick works, you might think it was magic. Try this light magic trick and amaze your friends!

What's happening?

You are seeing light change directions. If light just travels through one material, such as air, it travels in a straight line. But when light passes from one material to another, say from water to air, it changes direction. The light changes direction so much that the light bounces back into the glass. None of the light from the coin reaches your eyes, so it vanishes.

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Materials you'll need

Step-by-step tutorial

Step 1
Gather the materials you need to do the disappearing coin trick.

Step 2
Place the empty glass on top of the coin. Observe the coin through the side of the glass. You will notice that you can clearly see the coin.

Step 3
Pour a little bit of water into the glass. While you are pouring, keep watching the coin from the side. Continue to add water until you can't see the coin. It vanished!

Final result!
Now, peek in from the top of the glass. There's the coin! Show off this cool light experiment to your friends and family, and explain to them how it works!