The law of Kirgoth - unchanging rules

After the discovery of electricity, it became widely used in industry, although research into its nature continued. Basic regularities were established, which allow us to calculate the simplest elements of the chain, using Ohm's law. But complex electrical circuits have already started appearing, and often with their calculations there were difficulties. At that time, thanks to the labors of the German physicist Kirgoff, Kirgoff's law appeared, which allowed to describe any electrical circuit.

Here it is necessary to make preliminary explanations on some elements of the chain. In an electrical circuit, a node is a connection of several (usually three or more) conductors that are suitable from different locations and after the connection of those diverging to other points. For an electrical circuit, a circuit is a closed path through which an electric current passes . The contour consists of several independent nodes, with each node occurring no more than once.

These laws have become a working tool for many generations of engineers, allowing you to solve the most difficult tasks. They deal primarily with branched chains. The first law of Kirgof states that the total current flowing into the node is equal to the sum of the currents flowing from it. Here you can draw an analogy with water. If two rivers are connected together, the amount of water flowing along both rivers is equal to the amount of water flowing further after the confluence of the rivers.

In principle, everything is clear and clear here. Just remember the law of conservation of energy. The Kirgoff law formulated above can be regarded as its consequence. How many electrons have come to the node of the chain, the same number of electrons must go. If all the current flowing into the node of the electrical circuit does not leave completely from the node, then accumulation of charge will begin in the node, and this does not actually happen. Everything completely corresponds to the current law of conservation of energy - nothing anywhere does not arise and does not disappear into anywhere.

No less easy to understand and the second law Kirgof. It deals with complex, branched chains consisting of several elements. Such a chain can be divided into a number of separate simple contours. If there are additional sources in the circuit, for example, a battery, then the electrons flowing in the circuit can receive additional energy or lose it on resistances and other elements.

Describing the behavior of the electric current in such circuits, the second law of Kirgof states that in an electrical circuit in a closed loop the sum of the EMF is equal to the total voltage drop in the circuit, i.e. The sum of the voltages in the closed loop is zero. Taking into account the law of conservation of energy, everything is also clear here. In a closed loop, energy can not be taken anywhere, except from an existing source. If the energy is taken from nowhere, then we can talk about creating a perpetual motion machine. In this case, the current passing through the closed loop will have to increase. In reality nothing like this happens, as there is no perpetual motion machine.

Apply the laws of Kirgof, both first and second, for the calculation of the elements of chains. First of all - to calculate the operating modes and determine the required values of the circuit elements. These elements can be connected in different ways, forming nodes and contours. Connections can be either sequential or parallel.

Due to the described laws, it is always possible to determine the operating modes of various elements, the voltages acting on them, the currents flowing, to pick up electrical products that are suitable for the operating conditions. These laws are often used by engineers in the calculation of a wide variety of electronic and electrical circuits. This calculation allows to ensure correct and durable work of the products.

That's what the laws of Kirghoff are, first and second. This is a simplified exposition, the formulas and possible examples of calculations are not given here, but the essence of the laws themselves is described, their relation to the law of conservation of energy is shown and examples of possible use are given.