Static electricity is the excessive or insufficient electrostatic charge on the surface of an object. Static electricity is a kind of electric energy, which stays on the surface of objects: static electricity is the result of unbalanced positive and negative charges in a local range; Static electricity is formed by the transfer of electrons or ions.
Electrostatic phenomenon is familiar to people. When the weather is dry, when you comb your hair with a plastic comb, it will produce a discharge sound. The pen holder rubbed with fur can attract small pieces of paper (when the charge density reaches 106c/m2); Cracking sound when taking off synthetic fiber clothes; Sparks can also be seen at night (air breakdown field strength 30 kV/cm); Fluorescent lamps, TV screens, tape recorders and other magnetic heads are easy to attach dust, which is a common electrostatic phenomenon in daily life.
Static electricity is the most basic understanding of electricity and the first concept of introduction to electricity. As early as the sixth century BC, the ancient Greeks discovered that rubbing amber and other things had the ability to attract light and small objects, which is what people call the phenomenon of rubbing electrification. 1600 or so, Gilbert, an Englishman, found that many ordinary substances would be attractive after being rubbed. He named this effect Viseisctica in Latin, and it arrived at 1650, Walter? Charlton began to use the name of English electricity that people use now. Using artificial methods to make amber and sulfur rub to generate static electricity, and studying the properties of static electricity from an academic point of view can be traced back to16th century. However, since the invention of batteries and generators, people's research on electricity gradually left the direction of static electricity. Until the19th century, with the development of fiber industry, static electricity caused production disasters, which attracted people's interest and attention.
In fact, when two different objects touch each other, there is a potential difference between them, which is called contact potential. Because of the contact potential, electrons will "run" from one object to another, so the original electrical balance of each object is destroyed. The electron that pushes is positively charged, and the electron that gets is negatively charged. Later, people found that the same kind of charges have the physical characteristics of mutual repulsion and different kinds of charges attract each other. Because the acceptance potential exists only between molecules in contact with each other, the motion of electrons generated by two objects is very small. The function of friction is to greatly increase the contact area between objects, and at the same time, the thermal motion of molecules is suddenly intensified, so the electrical effect is very obvious. Insulators are more charged because they can't conduct electricity. In short, the so-called charged phenomenon is a physical phenomenon caused by the redistribution of electrons.
Alessandro Voltal 745-1827, an Italian professor of natural philosophy, published the triboelectric sequence in 1796. If any two substances in this sequence rub against each other, the substance in the front position is always positively charged and the substance in the back position is always negatively charged. Such as+zinc, lead, tin, iron, copper, silver, gold, stone and ink. Later, many charged sequence theories appeared, which opened the way for the practical application of electrostatic electrification. At the same time, many talented scientists such as Ampere, Ohm, Henry, Faraday and Lengci have made outstanding contributions to the enrichment and establishment of electrical theory, which has made a big step forward for human understanding and research on electricity. However, the emergence of various theories also makes the debate about the mechanism of static electricity continue to this day.
Electrostatic phenomenon is the general name of electrical phenomena produced in the process of charge generation and disappearance. Static electricity has the following characteristics:
1. From the point of view of electrostatic hazard prevention, when the volume resistivity of the material exceeds1010Ω. M, the ability of materials to dissipate static electricity is obviously weakened. From the point of view of eliminating static electricity, the volume resistivity of materials should not be higher than1010 Ω m;
2. In general industrial production, static electricity has the characteristics of high potential, low power, low current and short action time, and the electrostatic potential on equipment or human body can reach tens of thousands or even hundreds of thousands of volts; It often reaches several hundred volts to several thousand volts under normal working conditions; This is much higher than the low voltage of 220V and 380V in the market, but the accumulated static electricity is very low, usually in the order of nano coulomb (nC, 10-9C). The electrostatic current is mostly microampere (μA, 10-6A), and the action time is mostly microsecond (μS, 10-6S).
3. Compared with flowing electricity, static electricity is greatly influenced by environmental conditions, especially humidity, with poor reproducibility, and there are many transient phenomena in electrostatic measurement. Static electricity is as dual as anything in the world: it can not only benefit mankind, such as electrostatic copying, electrostatic painting, electrostatic dust removal and other application technologies; It will also bring a lot of harm, such as petrochemical, electronic and electrical fields. As far as the production of electronic components and the assembly and debugging of electronic equipment are concerned, contact, friction electrification, human body electrification and grounding will all cause great losses. Triboelectrification and human static electricity are two major hazards in electronics and microelectronics industries. With the rapid development of electronic industry, the harm of static electricity is increasingly exposed and gradually attracted people's attention.