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This chapter is from the book

Making Water Detour

See what happens when you bring an electrified balloon close to a stream of water.

Step By Step


  • party balloon

  • flexible plastic ruler, or piece of PVC pipe

  • stream of water (from the tap in your kitchen sink)

  • piece of flannel (clean and dry) or paper towel

Open the tap so that a thin, steady stream of water flows out. Rub the balloon, the ruler, or the pipe against your hair, which should be clean and dry, or use the flannel (also clean and dry) or paper towel. Bring the balloon, ruler, or pipe close to the stream. What happens? Repeat the experiment using two balloons or two rulers instead of just one, with the stream in between.

A Step Further


  • setup for Experiment 16, "Tubes of Light," under Playing with Light: Optics

  • party balloon

How about guiding light?

Fun Facts

The water molecules have a very special property. You can think of them as having two separated opposite charges. Molecules with this property are called polar. When you bring a charged object close to the water, it attracts the opposite charge in the mobile water molecules more than it repels the charge with the same sign. The net result is attraction, as you can easily demonstrate by bending water toward you with the charged balloon. Once the stream of water is bent, light reflected in the inside walls of the stream will "go with the flow." You end up having electricity controlling the path of light.

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