Electric Charge
Electric Charge is a property of matter that causes objects like a rubbed balloon to pull or push on other things.
Rub a plastic spoon on a wool sock, then hold it over small bits of torn paper on the counter. The paper bits jump up and cling to the spoon. Pull the spoon away and they fall back down. That pull between the spoon and paper is like electric charge — rubbing gave the spoon a force that grabs nearby things.
Explaining electric charge by grade level
Rub a balloon on your hair and hold it near small bits of cereal. The cereal jumps up to the balloon. Rubbing moves tiny parts too small to see from your hair onto the balloon. Those extra tiny parts give the balloon a pull that grabs the cereal.
Projects that explore electric charge
Electric charge can build up on everyday objects and then jump through the air. In this experiment, you create an electrophorus and use it to generate sparks from static electricity.
A pull-tab hanging from a thread between two soda cans can swing back and forth on its own — powered entirely by static charge. One can connects to an electrical ground; the other connects to a source of static charge, such as aluminum foil placed on an old CRT screen. The charged can repels the tab toward the grounded can, where the tab dumps its charge on contact and swings back. This cycle repeats several times per second, and occasional sparks snap between the cans. Benjamin Franklin built a version of this same device to detect approaching lightning storms.
Static electricity — a buildup of electric charge on a surface — can pull lightweight objects through the air without touching them. You scatter Rice Krispies on a table, then balance a plexiglass plate on wooden blocks a few inches above them. Rub the top of the plexiglass with a wool sweater, and a negative charge builds up on the plate. The cereal pieces slowly stand on end, then leap upward and stick briefly before falling back. That jumping happens because opposite charges attract each other across the gap.
Electric charge pushes and pulls on nearby objects. Rubbing styrofoam with a wool sock builds up negative charge on the surface. When you bring your finger close to a charged pie plate, that charge jumps across the gap as a spark.
Electric charge causes objects to push or pull on other things nearby. After rubbing a balloon against natural-hair wigs, the balloon pulls tiny paper squares toward its surface. All four hair colors produce a similar effect, showing that charge transfers through rubbing regardless of hair color.
Electric charge is a property of matter that builds up when two surfaces rub together. Some materials transfer more charge than others. When you rub a balloon across hair, it gains enough charge to pull tiny paper squares toward it. Hair creates the most static by far, while ceramic tile produces none at all.