Electrostatics

Electrostatic . It is the branch of physics that studies the phenomena produced by distributions of electric charges, that is, the electrostatic field.

Summary

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  • 1 History
  • 2 Static electricity
  • 3 conductors and insulators
  • 4 Induced charge
    • 1 Friction load
    • 2 Induction charging
  • 5 Electrostatic phenomena
    • 1 Electrification
    • 2 Electric charge
    • 3 Principle of conservation and quantization of the load
  • 6 Sources

History

The phenomenon of static electricity has been known since ancient times, approximately from the 6th century BC . C. according to the information provided by Tales de Mileto. Scientific research on this phenomenon began when machines capable of generating static electricity could be built, such as the electrostatic generator built by Otto von Guericke in the 17th century . The relationship between static electricity and storm clouds was not demonstrated until 1750 by Benjamin Franklin .

In 1733 the French Francois de Cisternay du Fay proposed the existence of two types of electrical charges, positive and negative, noting that: Objects rubbed against amber repel. Objects rubbed against a glass bar are also repelled .

However, objects rubbed with amber attract objects rubbed with glass.

Du Fay and Stephen Gray were two of the first “electrical physicists” to frequent squares and lounges to popularize and entertain with electricity. For example, people are electrified and electric shocks are produced from them, as in the so-called electric kiss: a lady was electrified and then he kissed a non-electrified person.

Michael Faraday published in 1832 the results of his experiments on the nature of what had previously been thought to be different types of electricity, demonstrating that magnet-induced electricity, photovoltaic electricity produced by a voltaic cell, and static electricity were the same kind. From this moment on, the study of static electricity remained within that of electricity in general.

Static electricity

The electricity static phenomenon is due to a buildup of electrical charges on an object. This accumulation can lead to an electric shock when the object comes into contact with another.

Before 1832 , when Michael Faraday published the results of his experiments on the identity of electricity, physicists thought that static electricity was somewhat different from electricity obtained by other methods. Michael Faraday demonstrated that electricity induced from a magnet , electricity produced by a battery, and static electricity are all the same.

Static electricity occurs when certain materials are rubbed against each other, such as wool against plastic or shoe soles against the carpet , where the rubbing process causes electrons to be removed from the surface of a material and relocated to the surface of the other material that offers more favorable energy levels or when ionized particles are deposited in a material, as occurs in satellites when receiving the flow of the solar wind and the Van Allen radiation belts. The electrification capacity of the bodies by friction is called the triboelectric effect; There is a classification of the different materials called the triboelectric sequence.

Static electricity is commonly used in xerography, in air filters, in some automobile paints, in some subatomic particle accelerators, etc. Small components of electronic circuits can be easily damaged by static electricity. Its manufacturers use a series of antistatic devices and special packaging to prevent this damage. Today the most delicate field effect semiconductor components include internal antistatic protection circuits.

Conductors and insulators

Materials behave differently when acquiring an electric charge. Thus, a metal rod held by the hand and rubbed with a skin is not loaded. However, it is possible to charge it when a glass or plastic handle is used to hold it by rubbing it and the metal is not touched by hands when rubbing. The explanation is that the charges can move freely between the metal and the human body, which would discharge them as soon as they occur, while glass and plastic do not allow the circulation of charges because they electrically isolate the metal rod from the human body.

This is because in certain materials, typically in metals , the electrons furthest from the respective nuclei easily acquire freedom of movement inside the solid. These free electrons are the particles that will carry the electrical charge. By depositing electrons in them, they are distributed throughout the body, and vice versa, when electrons are lost, free electrons are redistributed throughout the body to compensate for the loss of charge. These substances are called conductors.

In contrast to electrical conductors, there are materials in which the electrons are firmly attached to their respective atoms. Consequently, these substances do not have free electrons and charge displacement through them will not be possible. By depositing an electric charge on them, electrification is insanely maintained. These substances are called insulators or dielectrics. Glass and plastics are typical examples.

The distinction between conductors and insulators is not absolute: the resistivity of the insulators is not infinite (but it is very large), and free electrical charges, practically absent from good insulators, can be easily created by supplying the right amount of energy to separate the an electron from the atom to which it is attached (for example, by irradiation or heating). Thus, at a temperature of 3000 K, all materials that are not decomposed by temperature are conductive.

Between good conductors and dielectrics there are multiple intermediate situations. Among them, semiconductor materials stand out for their importance in the manufacture of electronic devices that are the basis of the current technological revolution. Under ordinary conditions they behave like dielectrics, but their conductive properties are modified by adding a minuscule amount of doping substances. With this, it is achieved that the conductivity of the semiconductor material can be varied in response to the application of a variable electrical potential in its control electrode.

Certain metals acquire infinite conductivity at very low temperatures, that is, the resistance to charge flow becomes zero. It’s about superconductors. Once a closed-loop electric current is established in a superconductor, the electrons flow indefinitely.

Induced load

Induced charge occurs when a charged object repels or attracts electrons from the surface of a second object. This creates a region in the second object that is more positively charged, creating an attractive force between the objects. For example, when you rub a balloon, the balloon will stick to the wall due to the attractive force exerted by two surfaces with opposite charges (the wall surface gains an induced electrical charge since the free electrons on the wall surface are repelled by the electrons that the balloon has gained by rubbing; thus a positively charged surface on the wall is created by electrostatic induction, which will attract the negative surface of the balloon).

Friction load

In friction charging, a large number of electrons are transferred because friction increases the contact of one material with the other. The innermost electrons of an atom are tightly bonded to the nucleus, opposite charge, but the outermost electrons of many atoms are bonded very weakly and can be easily dislodged. The force that holds the outer electrons in the atom varies from one substance to another. For example, the electrons are retained more strongly in the resin than in the wool, and if you rub a resin cake with a very dry wool fabric, the electrons are transferred from the wool to the resin. Consequently the resin cake is left with an excess of electrons and is negatively charged. In turn, the wool fabric is left with an electron deficiency and acquires a positive charge.

Induction charging

A body can be loaded by a simple procedure that begins with approaching a loaded rod of insulating material. Consider an uncharged conductive sphere, suspended by an insulating wire. As the negatively charged rod is brought near, the conduction electrons on the surface of the sphere migrate to the far side of the sphere; as a result, the far side of the sphere is negatively charged and the near side is positively charged. The sphere oscillates closer to the rod, because the force of attraction between the near side of the rod and the rod itself is greater than that of repulsion between the far side and the rod. We see that it has a net electric force, even though the net charge on the spheres as a whole is zero. Induction charging is not restricted to conductors,

Electrostatic phenomena

The existence of the electrostatic phenomenon is well known since ancient times, there are numerous illustrative examples that today are part of modern teaching, such as the fact that certain materials are charged with electricity by simple rubbing.

Electrization

Electrification is called the effect of gaining or losing electrical charges, usually electrons, produced by an electrically neutral body. By contact: A neutral body can be charged just by touching it with another previously charged one. In this case, both are left with the same type of charge, that is, if one neutral body is touched with another with a positive charge, the first must remain with a positive charge. By rubbing: When rubbing two electrically neutral bodies (number of electrons equal to the number of protons), both are charged, one with a positive charge and the other with a negative charge.

Electric charge

It is one of the basic properties of matter. Actually, the electric charge of a body or object is the sum of the charges of each of its minimum constituents (molecules, atoms and elementary particles). Therefore, the electric charge is said to be quantized. There are two types of electric charge, which have been called positive and negative charges. Electric charges of the same class or sign repel each other and those of a different sign attract each other.

Principle of conservation and quantization of the load

Electric charges can only be produced in pairs. The total amount of positive electrical charges produced equals that of negative charges, that is, the total amount of electrical charge in any process remains constant. Furthermore, any localized charge on a body is always an integer multiple of the natural unit of charge, that of the electron .

 

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