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An introduction to the tiny charges that build up on surfaces.
Have you ever walked across a rug and felt a sudden 'zap' when you touched a doorknob? It’s not magic—it’s a tiny power plant living on your socks!
Everything in the world is made of tiny pieces called atoms. Inside these atoms are even tinier things called charges. There are two types: positive () and negative (). Most of the time, objects have an equal number of both. This means they are balanced and 'quiet.' However, when these charges get out of balance and pile up on the surface of an object, we get static electricity. It is called 'static' because the charges stay in one place instead of flowing like the electricity in a wall outlet.
Quick Check
What do we call it when tiny electrical charges build up on the surface of an object?
Answer
Static electricity.
How do these charges move? They need a little help! When you rub two different materials together, like a balloon against a wool sweater, you create friction. This friction acts like a slide for negative charges (). The negative charges jump from the sweater onto the balloon. Now, the balloon has 'extra' negative charges. Because opposite charges attract, the negatively charged balloon will try to stick to things that have more positive charges, like a wall or your hair!
1. Take a rubber balloon and rub it on your hair for seconds. 2. The friction moves negative charges from your hair to the balloon. 3. Slowly pull the balloon away. 4. Your hair will reach out to touch the balloon because the positive charges in your hair are attracted to the negative charges on the balloon!
Quick Check
What is the name of the force created when you rub two things together to move charges?
Answer
Friction.
You can see static electricity in many places! Have you ever taken clothes out of the dryer and found a sock stuck to a shirt? That is static cling. The clothes tumbled and rubbed against each other in the heat, swapping charges. Another example is a lightning bolt. Lightning is just a giant version of the tiny spark you feel on a doorknob. It happens when a massive amount of static charge builds up in clouds and suddenly jumps to the ground.
1. You walk across a fuzzy carpet wearing wool socks. 2. With every step, your feet rub the carpet, picking up extra negative charges (). 3. Your whole body now has a buildup of static electricity. 4. When you touch a metal doorknob, all those extra charges jump off your finger at once, creating a tiny spark and a 'pop' sound!
1. Rub a plastic comb through dry hair several times to charge it with static. 2. Turn on a sink so only a very thin stream of water is falling. 3. Hold the comb near (but not touching) the water. 4. The static charge on the comb will actually pull the water toward it, making the stream bend! This happens because the water molecules have charges that are attracted to the comb.
What happens when you rub a balloon on a sweater?
Which of these is a giant example of static electricity?
Static electricity involves charges that are flowing through a wire like a river.
Review Tomorrow
Tomorrow, try to explain to a friend why your socks sometimes stick to your pants when they come out of the dryer.
Practice Activity
Find a plastic ruler and some tiny scraps of paper. Rub the ruler on your sleeve and see if you can 'fish' for the paper scraps using static electricity!