Science!, Science! For Parties

Science! For Parties- Backwards When Wet

I don’t know about you but we here at the Eclectic Eccentric are firm believers in the saying that “a party isn’t a party until it there’s an optical illusion involved”. What’s that? You’ve never heard of that saying. Well, that’s odd because it is totally a thing. Anyway, where was I? Oh, that’s right optical illusions. Well in this edition of Science! For Parties, you’re going to learn how to make an arrow reverse course using nothing more than a glass of water.
For this trick, you’ll need a piece of paper, a permanent marker, and a clear glass of water. Using your marker draw an arrow pointing left or right on your piece of paper. Stand the paper up against a wall or something then slide the glass of water in front of the arrow. Or for something with a bit more showmanship place the glass in front of the paper and then fill it with water. Either way, as soon as the water is in front of the arrow the arrow with switch direction. If you’re really creative you could try any number of other pictures, words, or number sequences and reverse those as well.
It’s a pretty neat little illusion and its based entirely on light refraction. Refraction is the change in direction a wave goes through when it passes through a different medium. In this case, light waves are passing through the air, then the glass, then the water, then through the glass again, and finally back through the air to your eye. Added in to this refraction chain is the curve of the glass holding the water. The curved glass acts like a magnifying lens, changing the focal point of the light and causing the light you see to travel in different directions. The combined effects cause the light you see to be reversed thus you see an image that is the opposite of what is actually drawn.
So the next time you though a party, remember this neat little optical illusion and put it to some good use. Until next time remember that objects may be Backwards When Wet.

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