By Penny Noyce
Sometimes the simplest of home experiments can lead to great exploration.
Lots of parents are familiar with classic demonstrations of static electricity. Rub a balloon on your hair, and the balloon will stick to a wall.
Here’s another demonstration that is really quite impressive.
Take a comb and run it through your hair, or a family member’s hair, maybe backward, for a couple of minutes. Dry hair and a dry comb work best.
Then run a faucet at the lowest flow you can while still getting a continuous flow instead of a broken trickle.
With the side of the comb, approach the flow of water from the side as closely as you can without touching it. This may take several tries. If the comb gets wet, dry it and start over.
The stream of water will divert sideways. Which way? Why?
In the picture above, an undisturbed stream falls into one side of the double sink, while the comb diverts the stream into the opposite side.
Why does this happen? Would it still happen if the stream of water were stronger? Would it work with a trickle of oil instead of water? Does hot water work differently from cold water? If you let the comb lie around for a while, will it still work?
This experiment is closely related to one in the kit for Tumblehome Learning’s Desperate Case of the Diamond Chip, in which kids build their own electroscope to investigate the behavior of electrons.
Let us know if you try this experiment and what you think is happening. Did you try any interesting variations? Send photos!
Thanks to physics teacher Gary Garber, who showed us this experiment.