The purpose of this neat experiment is to demonstrate attracting and repelling forces between objects due to their electrical charges.
Things Required:
2 round balloons, 9 inches (23 cm)
Masking tape
String, 2 yd. (2 m)
Clean, dry, oil-free hair
Marking pen
Directions:
Inflate both balloons and tie their ends. Use the marking pen to label one balloon A and the other B.
Cut the string in half and attach one piece to the end of each balloon. Tape the free ends of the strings to the top of a door frame so that the balloons may hang about 8 inches (20 cm) apart.
Stroke balloon A on your hair about 10 times and gently release it. What happens?
Stroke one of the balloons on your hair about 10 times and hold it while an assistant rubs the second balloon on your hair. Gently, release both balloons. Now what happens?
This Is What Happens:
The two balloons are attracted to each other when only one balloon is stroked against hair and repel each other when both balloons are rubbed against hair.
Science Behind It:
Matter is made up of atoms, which have negatively charged electrons spinning around a positive nucleus. Electrons are rubbed off the hair and collect on balloon A; thus the balloon becomes negatively charged. Since like charges repel each other, these negative charges on balloon A repel the electrons in the atoms of balloon B, causing B’s surface to be more positively charged. Each balloon now has a different charge, so they are attracted to each other.
Rubbing both balloons on the hair results in a build-up of negatively charged electrons on their surfaces. The balloons repel each other because they have the same charge. There are enough repulsive and attractive forces between the balloons to cause them to move without being touched.
