What is needed

* One Balloon
* A short length of string (~one foot)
* Marker
* Your computer monitor

What to do

* Blow up the balloon and tie it off.
* Tie the string near knot on balloon.
* Rub the balloon on your wall, clothes, cat, carpet, etc.
* Let the balloon hang by the string and then slowly move it toward the monitor. Does it turn?
* Grasp the balloon, making sure the side that faces you stays facing you. Why is this important?
* Use the marker to make a smiling face on the side facing you.
* On the opposite side, make a unhappy face.
* Again let the balloon hang and move it toward the monitor. What happens?
* To have the smiling face looking at you when the balloon is near the monitor, what do you have to do?
* Try turning off the monitor while the balloon it next to it.
* Leaving the balloon in place turn on the monitor again.

What is happening

When the balloon is rubbed against something, it develops a charge from the friction. Since the balloon is an insulator, the charge willstay right where it is. You probably charged up one side of the balloon more than the other, so when you bring it toward the monitor, the balloon will rotate: if the balloon is charged up the same as the monitor, it will turn away. If it is charged up opposite to the monitor, it will turn toward it. This will happen over and over, so you can draw faces on the balloon to mark the sides.

Try turning your monitor on and off while you do this. Your monitor makes a lot of static charge, and it changes when turned on and off. Does this change the attraction or repulsion of the balloon?