This post is part of a series of static electricity activities. Check out the whole series!
Cold and dry winter weather means chapped lips and dry skin for most folks. For a physicist, dry winter air means just one thing. It’s time to pull out the static electricity demonstrations!
Each Monday I will feature a quick, easy static electricity activity to take advantage of the dry, winter air.
Let’s start with the most basic example.
Take a balloon and rub it on your hair for at least 15 seconds.
Look in a mirror and hold the balloon a few inches from your head. Your hair should jump up and reach for the balloon.
Give the balloon a few more rubs on your head and then stick it on the wall. It should hang right there for quite a while. I’ve seen balloons stick to a classroom wall for up to 30 minutes on a very dry day.
So what is going on here?
The basis of electricity of any type is the electron. Electrons are tiny, negatively charged parts of the atom that swarm and spin around the central, positively charged nucleus. For some materials, called conductors, including most metals, these electrons can easily move from one atom to another. Other materials, called insulators such as plastics, hair or fur, hold on to their electrons more tightly.
The electricity that we use to power our appliances and electronics is just a flow of electrons through a wire. But static electricity involves electrons that are stuck in one place. We can create a static charge by rubbing together two insulators – for example a balloon on your hair. Friction moves the electrons from one insulator to another leaving the balloon negatively charged (it gained some electrons) and your hair positively charged (since it lost electrons).
It’s true – opposites attract and likes repel – at least when it comes to static electricity. Two negatively charge objects will push away from each other and oppositely charge objects will pull towards each other.
So when the negatively charged balloon is placed near your positively charged hair, they will attract each other.
You can even have a charged object pull towards a neutral object like a wall. The wall is made of atoms just like everything else and placing the balloon on the wall will polarize or move more positive charges towards the balloon and negative charges away, so that there is a pull between the negative balloon and the positive charges in the wall.
Check back each Monday for another hair-raising static electricity activity!
PS Too young to get my title reference? Check out this song by the Bangles.