Winter is a notorious time for giving and receiving – shocks that is! The electrostatic shock, also known to people as static electricity, is especially bad this time of year thanks to our cold, dry winter air.
We have all experienced it. After driving in the car, you step out and close the door and as soon as your finger touches the metal...zap! Or, you pull your clothes from the dryer and they are all stuck together. What is this seemingly magical force that is holding your clothes together or creating exciting shocks between you and other objects?
The answer lies in the very structure of materials. All solid materials are made up of atoms. Every atom contains a certain number of electrons (negatively charged particles) to balance the positive charge of the protons (positively charged particles) in the atomic nucleus. Electrons are held in place around the nucleus by electromagnetic forces. Under certain conditions, the electrons can break free from that force and travel. This usually happens when two different materials come into contact with each other. This movement of electrons can cause a buildup of charge, where one material will have gained several electrons and have a negative charge, and the other will have lost electrons so is left with a positive charge. These charges then remain on the object until they either move slowly into the ground or are quickly neutralized by a discharge.
The how and when this discharge will happen are a little more complicated. Atoms are always seeking to balance themselves. If they have a negative charge, as soon as they come into contact with something with a more positive charge, the electrons will quickly move into the object with the positive charge to restore the balance (and then you feel that familiar shock!). Or, if two materials rub together and one ends up with a positive charge and the other with a negative charge, the two materials will stick together (creating that familiar static cling!). Then when you try to pull the two materials apart, the electrons move quickly to try to restore balance and you see the bolts of static and hear the crackle of energy!
There are lots of ways to reduce your chances of encountering static cling. Dry conditions are very conducive to static cling, so try using a humidifier in your house to add moisture into the air. If your clothing is clinging to your body, try using a moisturizer to make your skin less dry or wear clothes made from natural fibres. Cotton tends to produce less static cling than polyester. One sure-fire method is to use dryer sheets when drying your clothes in the dryer. These sheets are cationic (meaning they have a positive charge). Laundry detergent is anionic (negatively charged) so when a dryer sheet is added to your load of laundry, it helps to balance the charges, making them neutral and thus reducing static cling.
Although static cling can be bothersome, it has some very important practical and beneficial applications. Plastic wrap is a great example of a product that wouldn’t work without it. Most thin plastic films can easily pick up a static electric charge by friction. When the plastic wrap is pulled from the roll, or it brushes against your sleeve, the friction causes electrons to be displaced onto one area of the plastic, giving it a negative charge. The surface that lost the electrons would then have a positive charge, and opposites attract! So, whether it is the plate of food you are going to wrap up or your sleeve, the plastic wrap will cling to the surface by electrical attraction.
So next time you get a little shock from electrons being discharged, just think of the cool science behind this tingling experience.