Observations and results
What happened to the flow of water when the statically charged cup came close to it? What happened when you took the statically charged cup away? Why do you think this happened?
When you rubbed the Styrofoam cup in the hair, negative charges (electrons) moved from the hairs to the surface of the cup, giving the cup a negative charge. The water falling out of the top cup is made out of positive and negative pieces that are all jumbled together. But as the negatively charged cup approaches the stream, the positively charged parts of the water molecules (the hydrogen atoms) are attracted to the negative charge and move the whole stream toward the cup.
Why doesn't the water get pulled all the way sideways to attach itself to the surface of the cup? Even though the static electric pull between the negative and positive forces is strong, the water is still heavy enough to be pulled down by gravity. So when you take the charged cup away from the stream, gravity takes back over entirely and pulls the water straight down.
Share your water bending observations and results! Leave a comment below or share your photos and feedback on Scientific American's Facebook page.
Pour out the water and carefully remove the toothpick. You can rinse and reuse the Styrofoam cups that don't have a hole in them.
More to explore
"Why Are Lightning Bolts Jagged Instead of Straight?" from Scientific American
"How Do Batteries Store and Discharge Electricity?" from Scientific American
"Static Electricity: Learn about static charge & static shock" from Science Made Simple
"Structure of the Atom" from New York University
Where Does Electricity Come From? by C. Vance Cast, ages 4–8
Benjamin Franklin's Adventures With Electricity by Beverley Birch, ages 9–12
Under Pressure: Launch a Balloon Rocket
What you'll need
Balloon (Long ones work best, but a round one will do, too.)
Piece of string at least 10 feet long
Two chairs or sturdy door handles about 10 feet apart (with clear space in between)
Balloons of other shapes and sizes (optional)
Other thin materials that can work as a guide wire, such as fishing line, ribbon or twine (optional)
Stopwatch or clock that indicates seconds (optional)