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# Basics of electrical engineering - the simplest electrical calculations

Electrical engineering - the field of technology associated with the production, distribution, conversion and use of electrical energy. And also - with the development, operation and optimization of electronic components, electronic circuits and devices, equipment and technical systems.

Electrical engineering is also understood as a technical science that studies the application of electrical and magnetic phenomena for practical use. Electrical engineering emerged as an independent science from physics at the end of the 19th century.

Currently, electrical engineering as a science includes the following scientific specialties: electrical engineering, TOE, lighting engineering, power electronics. In addition, power engineering is often referred to as a branch of electrical engineering, although the legitimate classification regards power engineering as a separate technical science. The main difference between electrical engineering and low-current electronics is that electrical engineering studies the problems associated with large-sized power electronic components: power lines, electric drives, while in electronics the main components are computers and other devices based on integrated circuits, as well as integrated circuits scheme. In another sense, in electrical engineering, the main task is the transfer of electrical energy, and in low-current electronics, information.

The law of ohm is an empirical physical law that determines the connection of the electromotive force of a source (or voltage) with the strength of the current flowing in the conductor and the resistance of the conductor. Established by Georg Om in 1826 and named in his honor.

Connection of conductors - Serial and parallel connections in electrical engineering are two main ways of connecting elements of an electrical circuit. With a serial connection, all elements are connected to each other in such a way that the part of the chain including them does not have a single node. With a parallel connection, all the elements in the chain are connected by two nodes and do not have connections with other nodes, if this does not contradict the condition. When connecting conductors in series, the current in all conductors is the same. The total voltage in the circuit is equal to the sum of the voltages at the ends of each of the conductors. When connected in parallel, the voltage drop between two nodes connecting the circuit elements is the same for all elements. In this case, the reciprocal of the total resistance of the circuit is equal to the sum of the values ​​inverse to the resistances of parallel-connected conductors.

Kirchhoff's rule - (often in the literature mistakenly referred to as Kirchhoff Laws) - relationships that are performed between currents and voltages in sections of any electrical circuit. Kirchhoff rules allow you to calculate any electrical circuit of direct, alternating and quasi-stationary current. They are of particular importance in electrical engineering because of their versatility, since they are suitable for solving many problems in the theory of electrical circuits and practical calculations of complex electrical circuits. Applying the Kirchhoff rules to a linear electric circuit allows us to obtain a system of linear equations for currents or voltages, and accordingly, to find the values ​​of currents on all branches of the circuit and all interstitial voltages. Formulated by Gustav Kirchhoff in 1845. The name “Rules” is more correct because these rules are not fundamental laws of nature, but follow from the fundamental laws of conservation of charge and non-vortexity of the electrostatic field (the third Maxwell equation with a constant magnetic field). These rules should not be confused with two more Kirchhoff laws in chemistry and physics.

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