Voltage is an important concept of electrical engineering
Electricity is the most used by manform of energy. Without exaggeration, we can say that the definition of electric current as an ordered motion of electrons is well known even from the school textbook of physics. But that's what voltage is and how this "ordered movement" is provided, not everyone will answer. Recall that an electron, an elementary electric charge, does not move by itself along a conductor. On the other hand, only the motion of charges along the chain is accompanied by the performance of useful work in the form of the transformation of energy from one species into another. It is due to these transformations that the electric current in some cases glows the thread of the light bulb, while in others it turns the rotor of the electric motor. In the first case, we have the conversion of electric energy into thermal energy, and in the second case to the magnetic one. The energy of moving charges is consumed by a source that supports the electric current in the circuit. Running along the conductor, the current transfers the energy of the EMF source to the consumer - the filament, the winding of the electric motor, etc.
If we define the current as the number of charges,proceeding along the conductor, it can be said that the operation of the current depends on the number of these charges per unit time. And on what does the electric current in the circuit depend? Let us consider a model of current flow by the example of a water jet flowing from the hole in the lower part of the cylinder filled to the top. Let us imagine that in our model the cylinder is a conductor, and water is a large number of electron droplets. Then it is quite clear that the amount of water flowing per unit of time depends on two parameters - the pressure of the water column, which in electrical circuits is referred to as the voltage of the current, and the diameter of the hole - the analog of the electrical resistance. The height of the water column in this model determines the upper potential of the energy source, the droplet-charges are similar to the flow of electrons that move from the upper layer to the lower one. The potential energy of the water mass, i.e. ability to perform some useful work, on the upper and lower levels is different. Due to the potential difference, water can flow out of the hole and with the conversion of the potential energy of the water column into the kinetic energy of the water jet. If the height of the water column is increased, then the potential difference, or voltage, increases, and the current strength, more precisely, the mass of water flowing per unit time, also increases. Thus, the proposed model shows a directly proportional dependence of the current strength on the voltage.
In the theory of electricity, this conclusion is written downas follows: I = f (U) * K, where I is the current, U is the voltage, and K is the individual characteristic of the reaction of the electrical circuit to the passing current-conductivity. In engineering, the inverse conductance value R = 1 / K is usually used, and it is called "resistance". The resistance is usually treated as a useful circuit load. In our model, such a "resistance" is the area of the hole for draining the water: the larger it is, the greater its permeability, or, in the language of electrical engineering, conductivity, and hence the resistance to the flow of water decreases.
The model clearly shows how the potentialThe energy of the droplet-charge flow is transformed into the kinetic energy of the outflowing jet. The lower the resistance (or more conductivity), the more mechanical work is performed on the mass of water. In other words, useful loads of different types are current converters, for example, a filament converts electrical energy into thermal and light, the relay coil converts electric energy into magnetic energy, and so on.
Returning to the electrical circuits, we can conclude that the current I and the voltage U are electrical parameters that determine the operation of the current A (A = U * I).
In this case, the current strength is determined by the quantitythe transferred charge, and the voltage is the reason that causes the electrons to "be ordered" from the larger potential to the smaller. If there is no voltage, then no amount of free electrons in the substance will lead to a movement of charges. This means that the absence of voltage does not lead to the transfer of energy.
A good demonstration of the findings ishydroelectric power stations: they are built using a large difference in water levels (potentials). Here the mass of the falling water is similar to the current, and the difference in the levels of the upper and lower dams plays the role of a potential drop.
