Where to get static electricity

In this slideshow the man picks up electrons as he walks over the carpet:. The carpet is covered with electrons. As the man walks, he picks up electric charges. When they shake hands the electricity discharges through the woman, giving her a shock. Many everyday applications of modern technology crucially rely on static electricity. Air fresheners not only make the room smell nice, but they really do eliminate bad odors by discharging static electricity onto dust particles, thus dissembling the bad smell.

Similarly, the smokestacks found in modern factories use charged plates to reduce pollution. As smoke particles move up the stack, they pick up negative charges from a metal grid.

Once charged, they are attracted to plates on the other sides of the smokestack that are positively charged. Finally, the charged smoke particles are collected onto a tray from the collecting plates and can be disposed of. Static electricity has also found its way into nanotechnology, where it is used, for instance, to pick up single atoms by laser beams.

These atoms can then be manipulated for all kinds of purposes as in various computing applications. Another exciting application in nanotechnology is the control of nanoballoons , which through static electricity can be switched between an inflated and a collapsed state.

These molecular machines could one day deliver medication to specific tissues within the body. Static electricity has seen two and a half millennia since its discovery. This article was coauthored by Muhammed Ibrahim , a system engineer at an environmental software company. He is conducting collaborative research with Dr. Sebastian Deffner on reducing computational errors in quantum memories.

This article is republished from The Conversation under a Creative Commons license. These substances exist in dynamic equilibrium; they are modified constantly due to the continual opening and closing of silicon-oxygen bonds, but have no net change. In the material transfer mechanism the driving force for creation of the charges is the input of mechanical energy during the contact of the polymers.

Research advances have also been made recently for rubbing contacts between two polymers. In , Chong-yang Liu and Allen Bard at the University of Texas at Austin, and independently Toribio Otero at the Polytechnic University of Cartagena in Spain, proposed an electron transfer mechanism on the basis that, after separation, the surfaces were able to induce several electrochemical reactions that can only be caused by electrons.

Their interpretation was challenged in by Silvia Piperno and her colleagues at the Weizmann Institute of Science in Israel, who proposed an ion transfer mechanism based on the transfer of material containing polar species. Also in rubbing contacts between two polymers, bipolar charging patterns were reported in by Nikolaus Knorr of the Sony Materials Science Laboratory in Stuttgart, Germany. Triboelectric charging results from contact between surfaces, but precisely what is meant by each of these terms is not defined or understood as they relate to charging.

My interest has focused on these questions: How are triboelectric charging mechanisms related to the depth of a polymer surface the charge penetration depth , and how does this depth vary as a function of the nature of the contacts? Many different types of contact have been employed in innovative experimental designs, but apparently no efforts have been made to study this factor as a controlled primary variable.

In the many studies of triboelectric charging of polymers, no account was taken of the fact that polymers are typically not compositionally or morphologically homogeneous as a function of depth.

Figure 7. In order to study how polymer composition at different depths affects charging, the author used metal and coated beads bouncing down a polymer-layered metal plate. The results can now be seen as supporting material transfer, as metal beads gouge a deeper layer and affect the inner layers of the polymer film. It is well known that low-surface-energy additives in polymers will migrate to the surface if films are fabricated from solution so as to allow thermodynamic equilibration of the components.

I used this phenomenon while at Xerox in the mids to investigate charge penetration depth. A series of polymers was prepared whose topmost compositions, determined by X-ray photoelectron spectroscopy, were designed to be different from the known bulk compositions.

Triboelectric charging was determined by cascading small and micrometer beads, both bare metal and polymer coated, over inclined polymer films cast on aluminum plates, a method of established precision and reproducibility. The bouncing contacts were light and brief, having a calculated contact time of 0.

The surprising finding was that contact charging between two polymers relates to their topmost molecular layers, but between a metal and a polymer it relates to layers beneath the polymer surface. The hypothesis was that the former results from ion transfer between the topmost surfaces and the latter involves electrons tunneling into the bulk, thus postulating a relationship between charging mechanism and charge penetration depth, which is supported by the fact that ions are known to adsorb to polymer surfaces and electrons are considered to burrow into them.

In view of the new evidence for a material transfer mechanism, I have subsequently reported that the above results can equally well be interpreted by material transfer: Contact of a polymer film with a rough, hard metal surface, on account of its greater applied force, gouges out a deeper layer than contact with a smoother, softer polymer surface.

It follows that electron, ion and material transfer mechanisms can possibly occur simultaneously, depending on the materials and conditions of contact. For metal-insulator contacts, the electron transfer mechanism has been sufficiently established under some circumstances.

For contact between two insulators, the issue is whether material transfer is the only or the predominant mechanism in all contacts. Alternative concepts include a threshold of applied force or energy below which insufficient material is transferred to cause charge exchange, or a continuum of contact types in which electron, ion and material transfer all take place, with elevating involvement of the latter with rising force or applied pressure.

Quantitative evidence by Law and his colleagues in for ion transfer is of interest in this context. Toner coated with a cesium salt was gently tumbled with polymer-coated carriers. Linear correlations were found between charge exchange and the degree of cesium transfer as a function of mixing time, providing strong evidence for a cesium-ion transfer mechanism. Mobile ions, by their very nature, would transfer more easily than fragments of a polymer, which would require bond cleavage.

Could this mean that the mechanical forces between toner and carrier were too low for simultaneous transfer of polymer fragments? Is there a hierarchy of charge exchange mechanisms, so that several mechanisms can contribute to charging in accordance with their position in the ranking, until a limiting charge is attained? A phenomenon that continues to puzzle experimenters is that contact charging occurs between materials of identical compositions.

As stated in a review paper by Daniel J. Lacks and R. A material charges positively relative to all the materials below it in the series, which implies that a difference of composition is necessary for contact charging.

Yet charging occurs when identical polymers are either pressed or rubbed together, symmetrically or asymmetrically. Asymmetric rubbing of polymer films results when a small area of one polymer is contacted with a larger area of the other. The direction of charging is dependent on the materials involved.

As is frequently the case, it is such unexpected phenomena that are likely to provide critical mechanistic information. I have proposed a mechanism for charge exchange between identical materials as an extension of the concept that the depth from which material is transferred from a polymer surface increases with applied force. Asymmetric rubbing results in unequal forces applied to each surface, so that material from different depths would be transferred.

Because polymers are typically inhomogeneous in their vertical compositions, this asymmetry would cause the transfer of material of different compositions, resulting in net charges of different signs in the bipolarly charged separated surfaces. Alternatively, differences in the degree and type of mechanical force applied to each surface could result in subtle differences in the mechanochemistry, chemical reactions resulting from the application of mechanical force.

Sufficiently different compositions of polymer fragment ions could be created at the two surfaces where charge exchange occurs. This new mechanism could also apply to symmetrical rubbing and pressing of identical polymers on the basis that small, unintentional degrees of asymmetry could result in sufficient asymmetric compositional transfer to result in charging.

It would apply equally well to charging between materials of different compositions and, in this way, contributes to the understanding of the general material transfer mechanism. Differences in hardness or softness could also contribute to asymmetric material transfer. The use of polymers designed to have compositional inhomogeneity as a function of depth, such as those described in experiments earlier, would provide a sensitive test for this hypothesis because the transfer of materials with different compositions would be easily detected.

Triboelectric charging of compositionally identical materials also happens with particulate matter, as in dust storms and the industrial handling of fine particles. Again, such occurrences could come from asymmetric contacts that result from differences in particle size. The larger particles charge positively and the smaller particles negatively.

An electron transfer mechanism has been proposed in which electrons trapped in high-energy surface states transfer to lower-energy states in other particles during collision.

Previous research has been done with the assumption that surface compositions and other surface characteristics do not vary as a function of particle size, which could be incorrect.

Figure 8. The everyday occurrence of static may soon be better understood due to new research. David R. Frazier Photolibrary, Inc. There is an increasing need to create materials that do not charge upon contact, perhaps most importantly because of the continued miniaturization of electronic equipment, which renders it even more susceptible to damage by even low-voltage discharge. Another motivation is pure research, whose objective is the understanding of natural phenomena and observable facts with no specific application or problem solving in mind.

For contact between two polymers, studies of the interaction between variables relating to polymer composition and contact type should throw light on key questions such as: For contacts involving polymers containing mobile ions, what are the factors affecting the contribution of ion versus material transfer?

And when a metal is involved, what are the factors affecting the contribution of electron versus material transfer?

In addition, recent developments have brought attention to the need for the application of mechanochemistry, which is central to the material transfer mechanism. Integrating the separate pieces of the puzzle into a coherent overall picture will take multidisciplinary efforts. Complex problems increasingly require input from several scientific disciplines.

Additionally, the concussion from the blast can cause traumatic internal injuries and permanent hearing loss, and the bright flash can cause temporary or permanent vision damage. As an example of the tremendous energy released in a lightning strike, Marsh told Live Science about his personal observation of a large oak tree that was literally split in half by high-pressure steam created by a lightning strike.

If you can hear thunder, generally, you are already within striking range, according to the University of Florida. If you are outdoors when a storm approaches, you should immediately seek shelter in a building or vehicle and avoid touching any metal. If you cannot get inside, move away from tall objects such as trees, towers or hilltops, squat down, and if possible, balance on the balls of your feet making as little contact with the ground as possible, according to Brigham Young University.

While static electricity can be a nuisance or even a danger, as in the case of static cling or static shock, in other cases it can be quite useful. For instance, static charges can be induced by electrical current.

One example of this is a capacitor , so named because it has the capacity to store electric charge, analogous to how a spring stores mechanical energy.

A voltage applied to capacitor creates a charge difference between the plates. If the capacitor is charged and the voltage is switched off, it can retain the charge for some time. This can be useful, as in the case of supercapacitors , which can replace rechargeable batteries in some applications, but it can also be dangerous.

Electronic equipment such as older CRT computer monitors and television sets contain large capacitors that can retain a charge with up to 25, volts, which can cause injury or death even after the device has been turned off for several days. Another way to create a useful static charge is with mechanical strain. In piezoelectric materials , electrons can literally be squeezed out of place and forced to move from the region that is under strain.

The voltage due to the resulting charge imbalance can then be harnessed to do work. One application is energy harvesting, whereby low-power devices can operate on energy produced by environmental vibrations. Another application is for crystal microphones.