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.

Cleanup
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

Up next…
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
Plastic straw
Tape
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)

5 Comments

1. 1. karen00100 06:21 PM 5/5/11

   And, even more fun...rub the balloon aganist your hair and then place it on the nearest wall...
   
   I'm going to go home and see if the wall 'trick' works with a styrofoam cup as well. I'll have my grand-kids hypothosize what will happen.

   Reply | Report Abuse | Link to this

2. 2. R.Blakely 02:20 AM 5/6/11

   Check "Lord Kelvin's water-drop electrostatic generator" for more interesting electrostatic effects using water.

   Reply | Report Abuse | Link to this

3. 3. quixote218 04:03 PM 5/6/11

   Also fun: fill a sink (with a metal drain at the bottom) with water and let it become still and waveless. Then, walk across the carpet in your socks, sliding your feet instead of lifting them. (Works best when the air is dry.) Don't touch anything — especially the counter around the sink — but slowly lower a single finger to the water's surface. Slowly! When you are just a few millimeters from the water, it will start to rise up to meet your finger. If it gets close enough, the static will spark and ripples will propagate out from your finger — even though you never touched the water!
   
   This is especially fun for kids, because it requires no tools or fancy materials. It's like the magic is in their finger, and so then they get a better feeling about how magic is electricity, and electricity is matter, and matter is everything around us — including us. The difference between us and a muddy pool is mostly in the arrangement of the bits, and that's a difficult concept to get across because we feel that life is so very different than stuff.

   Reply | Report Abuse | Link to this

4. 4. Zernk in reply to quixote218 08:23 AM 5/7/11

   "The difference between us and a muddy pool is mostly in the arrangement of the bits."
   
   Thanks quixote - that's beautiful. My new email tag line. (nice experiment too!)

   Reply | Report Abuse | Link to this

5. 5. moi45 01:08 AM 1/11/12

   The only cause of this experiment to succeed is the ability to reform the Earth's surface in small quantity not as past but it take a meaning shape to control the surrounding environment so microscopes use nowadays is keen to us to watch and effect for who needs to make a difference or to play.Don't forget Mickey mouse cartoon.

   Reply | Report Abuse | Link to this