Eye Dropper Cartesian Diver Is it mind control or just a clever science trick? email to friend
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1. Fill the plastic soda bottle to the VERY top with water.
2. Fill the glass eyedropper 1/4 full with water.
3. Place the eyedropper into the soda bottle. The eyedropper should float and the water in the bottle should be overflowing. Seal the bottle with the cap.
4. Squeeze the sides of the bottle and notice how the eyedropper (called a diver) sinks. Release your squeeze and it float back up to the top. Squeeze again and observe the water level in the eyedropper (it goes up). Practice making the diver go up and down without making it look like you're squeezing the bottle. Amaze your friends with your ability to make the eyedropper obey your commands!

How does it work?

Squeezing the bottle caused the diver to sink because the increased pressure forced water up into the diver, compressing the air at the top of the eyedropper. This increased the mass of the diver causing it to sink. Releasing the squeeze decreased the pressure on the air at the top of the eyedropper, and the water was forced back out of the diver.

Additional Info

Learn how to make a Ketchup Cartesian Diver.