The "Shock" of Static Electricity

By Amy Cowen on February 10, 2011 8:00 AM

Static electricity can make your hair stand on end. Source: Chris Darling, Wikpedia

Ahhh.... winter. Snowpeople. Snowy days home from school. Hats, mittens, and scarves. Hot chocolate. And static electricity. Zap!

That's right, it's during the winter months that you are most likely to shock yourself on a door knob or when opening the refrigerator. And when you pull off your hat or pull on a sweater, your hair might just stand on end. Boing!

After getting zapped ten or a hundred times, you probably have learned to instinctively touch something as an intermediary first before grabbing a potential "shocker." But have you stopped to think about "why" you get shocked? And why things seem more "shocking" when it's cold outside?

It's not just winter doldrums at work—although if you scuff your feet across the carpet more in winter months, you certainly are upping your odds of a zinger of a zap. The reason winter days are more shock-prone than the lazy days of summer has to do with the level of moisture in the air. In the winter, more static electricity builds up in our homes because the air is drier. In the summer, water in the air can help dissipate the electrons that we pick up as we move around, but when the air is drier, the charge collects and clings to us, building up until... zap!

A "Charged" Environment

Static electricity isn't just a problem in the winter. The "charge" of atoms is constantly changing as materials and objects make contact and electrons are passed around (or donated). Which objects "donate" and which objects are more receptive depends on where the objects fall in the triboelectric series. The objects that gain electrons are negatively charged (because electrons themselves have negative charges), leaving the objects that donated the electrons positively charged. You may have heard that "opposites attract." When it comes to static electricity, it's totally true! When a positively charged object gets near a negatively charged object, there is a movement of electrons from the negatively charged object to the positively charged one. Zap! That flow of electrons is the "electricity" part of static electricity.

What materials surround you makes a difference in how much static electricity you encounter. If your room is carpeted, for example, you might get shocked more often than if your floors are bare. You may have been "shocked" going down a slide at a playground or emerged from a playground tunnel with your hair fully charged. If you've ever heard the crackle when a load of clothes is pulled out of a drier, you've heard static electricity. Drier sheets help eliminate that problem. But how? What you wear, too, makes a difference in how much static electricity builds up in and around you. You can get shocked at the grocery store, especially if you've been pushing a cart. And you might find that you're simply someone who seems to carry more of a charge than others!

Controlling the "Shock" Factor

Whether you want to get away from the "shock" if static electricity or find a way to control it, the following Science Buddies Project Ideas let you capitalize on the "charge" in these winter months as you explore, avoid, and even harness static electricity.

Rubbing Up Against Static Electricity (Difficulty: 1) Explore how static electricity builds up and what the role of friction is in the process. Does the number of times you rub a balloon change the amount of static electricity created?
How Do Different Materials React to Static Electricity? (Difficulty: 3)
Build an electroscope to see how much static electricity is created by different types of materials. Are you more shock-resistant in cotton or fleece?
Where There Is Charge, There Can Be Sparks! (Difficulty: 6)
Using household materials, you can build a Leyden jar capacitor that will enable you to trap and store static electricity—it's a bit like storing lightning in a jar! For the Ben Franklin buff, there's a connection here. But there's also a connection to the kind of touch screen used in popular Apple® products like the iPhone^TM and the iPad^TM. (Tip: You'll need a different kind of stylus for an iPad than an older Nintendo DS.)
Avoid the Shock of Shocks! Build Your Own Super-sensitive Electric Field Detector (Difficulty: 6-8)
Using the super-sensitive charge detector you build in this project, you can sense invisible electric fields—before you walk into or touch them!

Getting Started

If you are just beginning to explore electricity and electronics projects, be sure and review the Science Buddies Electronics Primer before you begin for an introduction to common terms and an overview of using a multimeter and testing a circuit with a breadboard.