What Is Static Electricity?


Zapping someone with your finger is sure to elicit a lot of laughs when you’re 11, but static electricity is one of those things that loses its magic with age. After all, it’s the bane of good hair days and, if you have cats, they probably don’t appreciate getting shocked whenever you pet them (sorry, Fluffy). So how exactly is static electricity created, and why does it seem to occur more frequently in the winter?

To hark back to a high school science lesson: Static electricity is created when there’s an imbalance between the positive and negative charges of two objects. Most of the objects you use on a daily basis are electrically neutral. In other words, the protons (positive charge) and electrons (negative charge) that make up their atoms balance each other out, and no one gets shocked. However, the outer electrons in an atom can move around more freely than protons, and sometimes they jump from one surface to another when two materials come into contact.

This often happens when friction is involved. A classic example of this is when you shuffle across a wool carpet while wearing rubber-soled shoes. Wool—like rubber, wood, glass, plastic, and fur—is an insulator. This means that the electrons in wool are more tightly bound to the atom and are unlikely to budge. Since rubber and wool are both insulating materials, an even stronger electrical charge is likely to build up in your body, Lifehacker explains.

Essentially, one object becomes more positively charged because it doesn’t have enough protons, while the other one becomes more negatively charged because it has too many electrons. If one of those charged objects—like you—were to touch a conductor, like a metal doorknob, then the charge would be neutralized. This release is what creates a shock, or static discharge. It’s all part of nature’s attempt to restore order and balance.

That brings us to the second part of the question. The reason static electricity is more common in the winter is because the air humidity is lower. The dry air is less conductive, resulting in more powerful zaps. The Moon and Mars, for instance, are especially dry environments, so future astronauts (or colonizers) should take measures to avoid shocking their electronic equipment. Although static electricity is usually harmless, under just the right conditions it can cause flammable substances to ignite or explode, and it can also be harmful to electronics.

It isn’t all bad, though. A controlled form of triboelectric charging, as static charges are also known, is the technology behind copiers and laser printers. The key is knowing how to control it—and there are a few tricks you can try at home to reduce your exposure to unpleasant shocks.

If you want to pet your cat without zapping her, dip your fingers in water first. This will help remove the charge from static electricity so you don’t pass it to along to your unsuspecting fur baby. Humidifiers also help by releasing more moisture into the air and making it more conductive. Lifehacker also recommends swapping out your rubber-soled shoes for leather ones (or just going barefoot), and avoiding wool socks and sweaters.

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Why Are Sloths So Slow?

Sloths have little problem holding still for nature photographers.
Sloths have little problem holding still for nature photographers.
Geoview/iStock via Getty Images

When it comes to physical activity, few animals have as maligned a reputation as the sloth. The six sloth species, which call Brazil and Panama home, move with no urgency, having seemingly adapted to an existence that allows for a life lived in slow motion. But what makes sloths so sedate? And what horrible, poop-related price must they pay in order to maintain life in the slow lane?

According to HowStuffWorks, the sloth’s limited movements are primarily the result of their diet. Residing mainly in the canopy vines of Central and South American forests, sloths dine out on leaves, fruits, and buds. With virtually no fat or protein, sloths conserve energy by taking a leisurely approach to life. On average, a sloth will climb or travel roughly 125 feet per day. On land, it takes them roughly one minute to move just one foot.

A sloth’s digestive system matches their locomotion. After munching leaves using their lips—they have no incisors—it can take up to a month for their meals to be fully digested. And a sloth's metabolic rate is 40 to 45 percent slower than most mammals' to help compensate for their low caloric intake. With so little fuel to burn, a sloth makes the most of it.

Deliberate movement shouldn’t be confused for weakness, however. Sloths can hang from branches for hours, showing off some impressive stamina. And because they spend most of their time high up in trees, they have no need for rapid movement to evade predators.

There is, however, one major downside to the sloth's leisurely lifestyle. Owing to their meager diet, they typically only have to poop once per week. Like going in a public bathroom, this can be a stressful event, as it means going to the ground and risking detection by predators—which puts their lives on the line. Worse, that slow bowel motility means they’re trying to push out nearly one-third of their body weight in feces at a time. It's something to consider the next time you feel envious of their chill lifestyle.

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Are Any of the Scientific Instruments Left on the Moon By the Apollo Astronauts Still Functional?

Apollo 11 astronaut Neil Armstrong left the first footprint on the Moon on July 20, 1969.
Apollo 11 astronaut Neil Armstrong left the first footprint on the Moon on July 20, 1969.
Heritage Space/Heritage Images/Getty Images

C Stuart Hardwick:

The retroreflectors left as part of the Apollo Lunar Ranging Experiment are still fully functional, though their reflective efficiency has diminished over the years.

This deterioration is actually now delivering valuable data. The deterioration has multiple causes including micrometeorite impacts and dust deposition on the reflector surface, and chemical degradation of the mirror surface on the underside—among other things.

As technology has advanced, ground station sensitivity has been repeatedly upgraded faster than the reflectors have deteriorated. As a result, measurements have gotten better, not worse, and measurements of the degradation itself have, among other things, lent support to the idea that static electric charge gives the moon an ephemeral periodic near-surface pseudo-atmosphere of electrically levitating dust.

No other Apollo experiments on the moon remain functional. All the missions except the first included experiment packages powered by radiothermoelectric generators (RTGs), which operated until they were ordered to shut down on September 30, 1977. This was done to save money, but also because by then the RTGs could no longer power the transmitters or any instruments, and the control room used to maintain contact was needed for other purposes.

Because of fears that some problem might force Apollo 11 to abort back to orbit soon after landing, Apollo 11 deployed a simplified experiment package including a solar-powered seismometer which failed after 21 days.

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