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Scientists have finally figured out the core mechanism behind static electricity.
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First discovered in 600 B.C., the underlying physics behind this phenomenon have been a mystery for thousands of years.
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According to a new study, the answer lies in the combined effects of micro-deformations and frictional forces caused by the rubbing together of two objects.
One of the first science concepts that most people get exposed to as kids is static electricity. Take a balloon, rub it on your head, and watch your hair stand on end. Or, the more accidental version—shuffle across a floor and touch a doorknob. Ouch.
You can explain the basic idea of static electricity to a kid fairly easily: rubbing two things back and forth on each other creates a buildup of electric charge, which can either zap you or act like a hair magnet, depending on which demo you’re doing. Slightly more technically, rubbing two objects together causes a positive charge to build up on one surface and a negative charge to build up on another. This is what causes those magnetic properties, and completing the circuit between the two charged surfaces is what causes those zappy discharges.
But shockingly (pun intended), the specific physical mechanism behind this super-common phenomenon has been a mystery to scientists since it was first observed in 600 B.C. Thousands of years of investigation, and we’ve never been able to crack it.
Until now. A duo of researchers just announced that they have finally solved the case in a new study published in the journal Nano Letters.
“For the first time, we are able to explain a mystery that nobody could before: why rubbing matters,” Laurence Marks, who led the study, said in a press release. “People have tried, but they could not explain experimental results without making assumptions that were not justified or justifiable. We now can, and the answer is surprisingly simple.”
That answer: bending. Almost all surfaces—even those that seem flat to the naked eye—have both texture and what the scientists behind this paper refer to as “protrusions.” As two surfaces rub back and forth over each other, those protrusions are bent in various different ways, which produces a voltage.
Then, the act of sliding—and the friction that this causes the system to experience—can take the charge buildup and move it around, leading to the static electricity we’re familiar with.
“In 2019, we had the seed of what was going on. However, like all seeds, it needed time to grow,” Marks said in a press release. “Now, it has blossomed. We developed a new model that calculates electrical current. The values for the current for a range of different cases were in good agreement with experimental results.”
So, there we have it—deformations and friction are the long-sought keys to static electricity. Surprisingly simple. Now, the team hopes that their discovery will be used by other scientists to solve serious problems presented by static electricity. The phenomenon is known to cause fires and hinder some very precise activities, like portioning out exact amounts of medications in powder form. Better understanding static electricity could lead to the development of solutions to some or all of these problems.
“Static electricity affects life in both simple and profound ways,” Marks said in a press release. “Charging grains with static electricity has a major influence on how coffee beans are ground and taste. The Earth would probably not be a planet without a key step in the clumping of particles that form planets, which occurs because of the static electricity generated by colliding grains. It’s amazing how much of our lives are touched by static electricity and how much of the universe depends on it.”
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