What is the electrical voltage

With the concept of "electrical tension" we all have to face almost every day, because the field of its use is not limited to electrical appliances alone. These are lightning discharges during the rain, and sparks on a plastic comb and clothing made of synthetic fabrics, etc.

The dry academic language gives the following definition to this phenomenon: electrical stress is a physical quantity indicating the amount of work performed by a charge in 1 Cl (Coulomb) work. The pendant, in turn, indicates the amount of charge passed through the conductive material in 1 second with a current strength of 1 A.

Another definition is also acceptable, according to which the electric voltage is the ratio of the work performed by the electric field on the displacement of the test (test) charge between two points, to the numerical value of the given charge. It is generally assumed that charge transfer does not affect the potential difference (does not change the voltage), and the path of motion can be ignored. As a formula, this definition is written as follows:

U = A / q,

Where U - voltage, A - work, q - charge.

To remember what is measured by the electrical voltage, there is no need for learning, because the prompt is always at hand, since all voltage sources indicate the voltage value and its dimension: it is enough to look at any battery. The unit of measurement is Volts (V, V).

The concepts of "electric voltage" for DC and AC circuits differ. In an alternating current, characterized by the periodic passage of the sinusoid through the zero mark, the calculation is not based on the instantaneous but on the actual value. This is possible due to the fact that its operation with an active linear load numerically corresponds to a constant voltage.

The one who happened to encounter three-phase electric motors, for sure, drew attention to a strange record in the passport characteristics. There, through the sign of the fraction, two voltages are indicated, for example, 220/380 V. There is no misprint, indeed, the equipment is capable of operating at two different effective values. Whence in a network 380 In can take 220? It turns out that the voltage can be either phase or linear, depending on the method of measurement. The phase is determined by measuring the value between each phase and the zero wire, and the linear one between the phase conductors. By connecting the load circuit to the triangle, it is possible to obtain the equality of the linear and phase voltages, and for the "star" scheme the phase phase is 1.73 times smaller than the linear one.

To measure the voltage is used a special device - a voltmeter. Its main feature is the need to connect current carrying probes parallel to the load. High internal resistance does not introduce shunt distortion. That is why, for example, in domestic applications, it is possible to connect directly to a power outlet (unlike an ammeter that is connected to a circuit break).

But let's leave the three-storeyed formulas for academicians and understand what is the "electric current voltage", speaking in simple human language. So, this is the difference of charges (potentials) between two arbitrary points of a conductor or electric field. A source that causes the movement of electrons along a conductor (generator, battery) creates on their one end an excess, and on the other - a defect. Accordingly, the value of charges is also different. It is enough to connect these points with any conducting medium, and an electric current will appear-the motion of charged particles, which tends to level out this difference. In other words, the nature of the current implies the desire of atoms to a stable state, disturbed by the magnetic fields of the generator. Voltage can exist without current, if the resistance between points is large. This explains the fact that the usual batteries are not "shocked".