Of course, in the 18th century people mostly made use of static electricity in magic tricks and other performances. Static electricity comes down to the interactive force between electrical charges. At the atomic scale, negative charges are carried by tiny elementary particles called electrons. Most electrons are neatly packed inside the bulk of matter, whether it be a hard and lifeless stone or the soft, living tissue of your body.
However, many electrons also sit right on the surface of any material. Each different material holds on to these surface electrons with its own different characteristic strength. This transfer of electrons — what we know as a spark of static electricity — happens all the time. Infamous examples are children sliding down a playground slide, feet shuffling along a carpet or someone removing wool gloves in order to shake hands. But we notice its effect more frequently in the dry months of winter, when the air has very low humidity.
Dry air is an electrical insulator, whereas moist air acts as a conductor. This is what happens: In dry air, electrons get trapped on the surface with the stronger binding force. When electrons have nowhere to go, the charge builds up on surfaces — until it reaches a critical maximum and discharges in the form of a tiny lightning bolt. Give the electrons a place to go — such as your outstretched finger — and you will most certainly feel the zap.
Though sometimes annoying, the amount of charge in static electricity is typically quite little and rather innocent.
The voltage can be about times the voltage of typical power outlets. However, these huge voltages are nothing to worry about, since voltage is just a measure of the charge difference between objects.
For the last decade and a half, Wang, an electrical engineer and nanotechnologist, has sought ways to scavenge energy from the movements of ordinary life. The energy problem is big: We need power in large doses to keep our cities lighted and cars running, and we need electricity in small doses — lots of them — to recharge batteries in our phones, fitness trackers and tablets.
Those demands have a cost. Renewable power sources, including sun, wind and water, provided another 17 percent or so of total energy demand. But harnessing the forces of nature involves challenges that are formidable — and currently unsolved. Even the bike lights and elliptical machines that convert exercise into electricity need a lot of OOMPH to work. Instead, Wang is pioneering an engineering effort to generate electricity with a small oomph. Like from footsteps. Or raindrops hitting a car.
Or the effort required to press keys on a keyboard. Or the small vibrations of a shirt, worn through the day. These ordinary motions, and others, could charge our devices and light our homes. Such a generator, Wang says, can enable that keyboard to harvest energy from keystrokes, or turn clothing into a mini power plant. He uses what is called the triboelectric effect. You already know about triboelectricity, if not necessarily by name.
The ancient Greeks observed that after rubbing a piece of amber with animal fur, the hardened tree sap would attract dust and other small particles. The word electric, coined by Elizabethan scientist William Gilbert, speaks to these origins: It traces back to elektron, Greek for amber.
Schoolteachers use the same amber-on-fur demonstration to introduce the fundamentals of electricity, showing that two rubbed amber rods will repel each other. Bored kids at birthday parties rub their heads with balloons to make their hair stand up, and to get the balloons to stick to walls.
The marvel of static electricity once seemed a promising way forward in the great electrification of the world. In , Prussian scientist Otto von Guericke, who was also the mayor of Magdeburg, generated eerie yellow sparks by rubbing a spinning sulfur ball with his hands. His invention is often recognized as the first electrostatic generator, and some Magdeburgians reportedly believed their mayor capable of magic. In , British physicist Michael Faraday unveiled the first electromagnetic generator, which uses a moving magnet to induce an electric current in a coiled wire.
That changed everything. Today, the generators in coal plants, wind turbines, nuclear power plants and hydroelectric dams — basically anything that works by converting physical movement into electricity — has an electromagnetic generator at its heart. Only photocopiers still make use of static electricity, in the form of distributed charges to direct ink on paper.
Lightning, the most violent display of static electricity, kills dozens of people every year in the U. Until , Wang barely gave a second thought to static electricity. He never meant to spark an energy revolution. But what he calls a happy accident in the lab revealed that triboelectric materials could produce big voltages, setting the scientist on a path to harvest them. But that outlook changed in the late s, when he started working at Oak Ridge National Laboratory in Tennessee and saw scientists using new materials to solve real-world problems.
When the materials are pulled apart, there tends to be an imbalance of electrons left over, with some of the atoms of the materials gaining extra electrons than others. This imbalance creates an electric charge on the materials, and the materials' atoms desire to return to neutral charge means electricity has been born.
The shock you get when touching a doorknob after walking across a plush carpet is your body's atoms discharging the extra electrons they collected from the carpet so they can return to neutral charge. Triboelectricity is unpredictable, but engineers in the last few years have been creating innovative ways to capture its potential, ranging from electrodes in car tires to wood boards that create static when stepped on.
One of the pioneers in this field has been Georgia Institute of Technology engineer Zhong Lin Wang , who has created triboelectric generators from a wide variety of materials , including ultra-thin polymers that could serve as touchscreens, fabrics and even recycled soda bottles.
For his latest triboelectric creation, Wang reached for a material few would associate with electricity at all—paper. As a child, Wang says he played with intricate creations made from cutting and folding paper. This East Asian art, which dates back thousands of years, is called "kirigami," translating to "cut paper" it's closely related to the more famous "origami," which means folding paper.
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