For Science! Why are static shocks so bad during the winter?
Friday, April 10, 2015, 9:51 - Plagued by static shocks during the winter months? Zapped every time you cross a room? On this episode of For Science!, we present a guide to static electricity, including what you can do to minimize the number of shocks that you must endure.
Getting a static shock once in awhile is annoying. However, during the winter months, especially if you're someone who is more prone to them, they can happen so often that it's - sometimes literally - nerve-racking. It can really have a negative impact on our mood!
The shock itself is just a buildup of charge, caused by our body collecting extra electrons from the surfaces around us. Walk across a wool or nylon carpet while wearing rubber-soled shoes, and electrons are drawn from the carpet fibres to the surface of the rubber.
The electrons spread out over the surface of our body from there, and the resulting charge buildup can get quite high. Reach out towards a metal doorknob, for example, and the voltage across the gap between your hand and the knob can climb to 20,000 Volts or higher - enough to break down the air resistance and cause a spark to jump the gap.
Why so bad in the winter?
Air is an electrical insulator, which means that electrons don't pass through it easily. Add water vapour to the air, and the water molecules allow electrons to pass more freely.
Since the amount of water vapour the air can hold is dependent on the air's temperature, in general, winter air holds less moisture than summer air. We make the situation even worse though, by taking cold, winter air and heating it up with our furnaces.
An an example, take Ottawa's temperature of -23oC and dewpoint temperature of -29oC from 8 am today (Feb. 23, 2015). Although those temperatures are quite cold, the combination gives us a reasonably comfortable relative humidity of 60 per cent. When a furnace draws some of that frigid air inside and heats it up - let's say to 18oC - the dew point doesn't rise with it, unless your furnace also includes a humidifier to add more moisture to the air. Inside, it can become as dry as a desert, making the air about as resistant to the movement of electrons as it can get!
REMEMBER! Dew point is the temperature of the air when condensation forms. The closer temperature and dew point are together, the higher the humidity. The further they are apart, the drier it is!
What can we do to prevent this?
Since the reason for the spark is the charge buildup, the easiest way to prevent shocks is to minimize the amount of charge that gets build up on our skin and clothes.
Given that we can't see this charge, that might seem daunting, but a few easy steps can help.
At home, consider running a humidifier to raise the amount of moisture in the air. That will allow electrons to pass throughout the room more easily, so that they can't build up as much.
Cotton is about the most electrically neutral fabric we wear, so sticking with cotton clothing, rather than wool, is best. Also, leather-soled shoes don't gather as many electrons as rubber-soled shoes, so switching you footwear can help too.
If those aren't options or they just don't help as much as they should, remember that the spark is caused by too much charge buildup. So, try touching metal objects more often, to discharge the buildup of electrons sooner, before you get enough gathering to cause a spark.
As a last resort, carry around a metal object, like a coin or your house key, and touch the doorknob, faucet or light switch with that first. It won't prevent the spark from jumping, but it will prevent it from jumping from your fingers, which will at least keep you from feeling the pain.
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