The cold dry air of winter is perfect for some hair-raising experiments. Have you ever noticed how your hair sometimes stands straight up when you pop out from under your snuggly blankets in the morning? When you try to comb your hair, it might even get worse! Did you ever wonder why this happens?
In the photo, the boy's hair is standing up for the same reason your hair is so hard to control in the cold, dry winter days. Some folks call their hair "staticy" when it stands up. The reason for the hair standing up is static electricity.
To understand about static electricity, let's first look at the material world around you. Everything you can feel, touch, see, smell, hear and taste is made up of matter. Matter is made of very tiny atoms and groups of atoms called molecules. These are too small to see, but they are really there. Atoms are made of even smaller parts. Without going into too much detail, we can simplify our view of atoms as having a positively charged central core called a nucleus.
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Surrounding the positively charged nucleus are negatively charged particles called electrons. Atoms normally have the same number of positively charged particles in the nucleus as there are negatively charged electrons surrounding the nucleus. When the atom has exactly the same number of positive and negative particles, the overall charge of the atom is zero or electrically neutral.
Some objects' atoms have outer electrons that can be easily removed by just rubbing one object on another. When this happens, a charge unbalance in normally neutrally charged atoms occurs. Many people have noticed this when you scuff your shoes on a rug or carpet on a dry winter day. Electrons are rubbed off of the carpet and onto your shoes and onto you! Shoes are usually made of plastic or rubber that holds on to the negative electric charge. If you touch an object that conducts electric charge like a metal doorknob or your friend you will see, hear and feel an electrical spark. The small spark you see is the result of the excess negative charge jumping to a less electrically negative object.
The lightning that you see during a thunderstorm is the result of very large-scale electrical sparking events between the ground and the sky. The thunder you hear is the very large scale "snap" or "pop" sound you hear from static electric sparks you create.
The static electricity generator in the photo has a rubber belt inside it that rubs as it goes around in a loop powered by a motor. As the belt moves around, it "charges up" with electrons and carries this excess of electrons to the spherical metal ball where they are stored. If a person's hand is also on the ball, the person can also "charge up" with a negative overall charge.
Did you ever hear the phrase "opposites attract"? When your hand is on the static generator your body, including your hair all takes on the same charge. If opposite charges attract, then if the charge is the same, the opposite happens and they repel, or push away, from each other - and ta-da! Your hair stands up!
Not everyone has a static generator, but you may have some of the materials at home to try your own static experiments.
Activity: Static Hair and Balloon
1) You will need a normal or party balloon.
2) Blow up (inflate) the balloon not quite to maximum size. You may need to get an adult to help you.
3) Tie a knot in the balloon to hold in the air. Do not be afraid to ask for help.
4) Make sure you do the next step after you wash your hair and before you apply any additional hair products to your hair.
5) While standing in front of a mirror, gently rub the balloon back and forth four to five times on your hair and slowly lift the balloon.
6) Notice that your hair is attracted to the balloon.
Electrons (negatively charged particles) from your hair have been rubbed onto the surface of the balloon making the surface of the balloon (that rubbed your hair) negatively charged with excess electrons. Your hair has fewer electrons and now has an excess of positive charges. Why does the balloon attract your hair? Remember - opposites attract.
Now that you know a little bit about static electricity, pay attention to all of the ways static electricity is around you every day. From the socks that stick together in the dryer to your unruly "morning hair," static electricity is all around us.
- Libby and Robert Strong and Richard Pollack work with the SMART Center, a hands-on science outreach and education organization in the northern Ohio Valley, the headquarters of which is located at the SMART-Centre Market, 30 22nd St., Wheeling. Visit them at www.smartcenter.org.
