Electrification of bodies: definition, conditions of occurrence, application

Have you noticed that when you take off your sweater or T-shirt, sparks fly and crackles are heard? And when you get out of the car and get an electric shock? This is static electricity or electrification of bodies. It arises as a result of the accumulation of electric charges of different signs on objects with their subsequent compensation. In this article, we will briefly consider this phenomenon, the reasons for its occurrence, as well as methods of application both in everyday life and in industry.

Definition

Electrification is the process of separating electrical charges and their accumulation in certain places of objects and bodies. The phenomenon occurs as a result of friction, contact of bodies or as a result of electrostatic induction. In simple words, when an object with an electric field is located nearby.

Recall: in physics, two kinds of charges are distinguished - positive and negative, or protons and electrons. Between them arises electric field. Like charges attract, and unlike charges repel.

The phenomenon is observed on power supplies and not only. Charges accumulate on dielectrics, everyone saw this in experiments illustrating the phenomenon with ebony and glass rods, which were demonstrated in physics lessons at school.

Initially, all atoms, everything that surrounds us consists of, are electrically neutral. As a result of the phenomenon of electrification, positive or negative charges appear on the surface of objects. Let us recall the school experience: if you rub an ebonite stick with a woolen cloth, after the friction stops, the stick will remain charged. Then the body is said to be electrified.

Thus, during friction, electrons were transferred from one object to another. As a result, after the termination of friction, excess electrons remained “not on their” bodies and an excess charge was obtained, and it ceased to be neutral. As a result of friction of the stick against wool or fur, a negative charge is formed on its surface.

Conditions for the occurrence of the phenomenon and methods of charge transfer

We told how this phenomenon is explained in nature, and now let's look at how you can electrify bodies. Immediately, we note that the fulfillment of all conditions is optional - electrification can occur for one reason or another, we divide them into two main groups:

The first is mechanical interaction. During friction, the distance between objects is comparable to the distance between the molecules in it. Since the electrons in one of the bodies are weaker bound to the nucleus, they are transferred to the other body. Impact and contact are other methods of electrification.

The second group is electrification by influence, that is, the phenomenon is observed when external forces are applied to the body, including:

• Electric field. As a result of the action of the field on the conductor, charges appear on its surface, and the smaller the bending radius of the surface, the more charges will accumulate here. So on the tip there will be the most charges, we discussed this issue in more detail in the article https://samelectrik.ru/kak-raspredelyayutsya-zaryady-v-provodnike-pri-protekanii-toka.html and here https://samelectrik.ru/chto-takoe-provodniki-poluprovodniki-i-dielektriki.html

• Exposure to light. Discovered by Professor A.G. Stoletov in 1888, is that when exposed to light on zinc, aluminum, cesium, sodium, lead, potassium and other metals they lose electrons and become charged positively.
• Warmth. When the metal is heated, the electrons are given enough energy to leave the metal, as a result, it acquires a positive charge.
• Chemical reaction. In the presence of two electrodes made of different metals, redox reactions occur, as a result, one of them becomes positively charged, and the other - negatively. We considered this in more detail in the article about anode and cathode.
• Under pressure. In piezoelectrics (quartz, Rochelle salt, ammonium phosphate), under mechanical action (compression or tension), positive and negative charges are formed on the faces.

These are the main types of electrification.

What laws of physics are associated with electrification

The phenomenon of electrification is associated with such physical laws as:

• Coulomb's law. Describes the force with which charges interact. In this way, you can determine how strongly electrified bodies are attracted to each other.
• Charge conservation law. It says that the algebraic sum of charges in a closed system is unchanged. This suggests that excess charges on electrified objects do not appear out of nowhere, but pass from body to body.

We have already considered these laws, you can find out more in the relevant articles to which we have referred.

Application in practice

The phenomenon of electrification has both positive and negative manifestations. Examples of positive applications:

1. The use of electrostatic dust filters for air purification in ventilation systems at work and at home. It is especially important if a lot of dust is generated during the production process.
2. Painting of cars and other metal products. With the help of electrostatic sprayers, it is possible to charge the paint negatively, the car body is grounded. As a result, paint particles are attracted to the car body parts. The paint quality is improved and the paint consumption is reduced.
3. Electrostatic smoking of meat and fish can significantly speed up the smoking process.
4. Creation of artificial fur or decorative fleecy coatings. Fine pile is passed through the mesh, due to interaction with the electric field, the pile falls in an even layer perpendicular to the surface to be coated, previously treated with an adhesive.

There are also a number of uses for cleaning, sorting, filtering, and in medicine to speed up healing.

The negative effects of electrification can lead to fatal consequences:

1. The occurrence of sparks when charged objects come into contact. Such cases include sparks in everyday life, which slip when you take off your sweater, when you get an electric shock when you get out of the car. For example, an airplane is electrified in flight, and when a ladder is brought up to it, sparks can slip through, and because of this, ignition is possible, therefore, first, the charge is removed from the airplane. There are also known cases of ignition of oil tankers due to electrification.
2. The phenomenon leads to the appearance of large electrical charges, they can lead to failure electronic components in technology, both in the production of technology, and in the process of operation or repair. This is due to the discharge of the tool onto the PCB. Therefore, electronics repair technicians should work with grounded electrical wristbands and grounded soldering irons and the like. The modern element base contains a number of technical solutions to minimize the effect of electrification on their operation. For example, installation of Zener diodes in parallel with the SHUTTER-SOURCE circuit of field-effect transistors.

Interesting! There is a known case when, when varnishing printed circuit boards after mounting electronic components, a large rejection was observed, despite the fact that all products were tested before varnishing. The question arose: how to get rid of the electrification problem? The problem was solved by grounding the spray gun.

To consolidate the material, we also recommend watching useful videos on the topic:

We briefly explained the phenomenon of electrification of bodies and told under what conditions the processes of the appearance of charges on objects occur. Electrification is important in manufacturing and has found many useful applications. Unfortunately, if you do not provide for ways to solve negative manifestations, to prevent unnecessary sparks in places with the likelihood of explosions, it will lead to serious problems.

Related materials:

• What is static electricity
• Electrical protective equipment in electrical installations up to 1000V
• How to protect yourself from electromagnetic radiation