Introduction

This chapter studies phenomena that have as their common cause the existence of electric charges and their movement under the influence of electric and magnetic fields.

Examples of electrical phenomena:

• Electrical discharges, which can be:

  • violent, such as lightning and thunder - impressive phenomena that have frightened and fascinated people throughout the ages;

  • slow, in the form of Corona discharges;

Several electrical phenomena have been known since ancient times:

• The electrification of bodies such as objects made of amber or glass by rubbing them with fabrics (cotton, silk, wool, fur), which thus acquire the property of attracting very light objects;

• Electricity produced by electric fish, which causes electric shocks;

• Magnetism: magnetic rocks (magnetite) have been discovered that attract ferrous metals;

At that time, however, it was not even suspected that electric discharges, electrification and magnetism are closely related phenomena.

The development of knowledge of electricity and magnetism began only after 1600, when systematic research discovered the existence of electric charges of two types and other phenomena caused by them:

• Electric charges form fluids that flow through conductors (electric current);

• The transmission of signals in the nervous system of living things takes place through electric currents;

• Through chemical reactions, electric current can be obtained: electric batteries work on this principle;

• Electric current produces heat, light, magnetic fields and influences chemical reactions;

• Electromagnetic induction: with the help of variable magnetic fields, electric current can be generated;

• The formation of chemical bonds: the microparticles that make up all substances (atoms, molecules) form bonds among themselves precisely because of the interactions between electric charges;

• Luminescent discharge, by spark, by electric arc;

• The external, internal photoelectric effect: it is the basis for the operation of photoelectric sensors and photovoltaic panels;

• Electric charges can be accelerated and thus electromagnetic waves are obtained, which propagate through space at the speed of light;

Applications of electricity in everyday life:

• Electricity production and transport;

• Conversion of electrical energy into heat, light and mechanical work;

• Obtaining metals from ores, covering objects with thin metal layers (galvanizing) and various processing;

• Radio, television and various means of transmitting information through electromagnetic waves;

• Information and communication technology;

 

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