Voltage refers to the energy characteristics of the electric field. There is another definition of the term: it is the ratio of work to the amount of charge transported through a conductor by a certain distance. The unit of electric tension in SI system is volt. It is named in honor of Alessandro Volta, who first in the world opened the cell and got a shock. Sometimes voltage value as the potential difference. For example, at one point the potential is equal to 13 and another to 10 V. Then the voltage between points will be equal 13 – 10 = 3 V.

## Record the voltage in practice

Depending on which voltage is applied in a particular system, use one or the other designation. If voltage more than 1000 V, use kV; if more than 1 million IN – MV etc gigavolt, nanovolt, micro volts.

Voltage is measured with voltmeters, which are divided into millivoltmeters, voltmeters, kilovoltmeters, etc.

## Three-phase network

The entire energy system of the planet is based on a three-phase network. It carries two kinds of stress: linear and phase. The linear voltage is a voltage between the two conductors, and the phase – between the conductor and the neutral wire, or zero. So when we connect the load in the triangular diagram, the line voltage is equal to phase, and when we connect the load in a star schema, then the linear voltage increases in the square root of three times. Hence such designations three-phase network, or as a 220/380 V 127/220 V. the First number indicates the phase voltage, and the second – linear.
For a General idea of the values of electric voltage at various sites, give them.

## Voltage on some objects

The voltage between the electrodes when you remove the electrocardiogram, is 1-2 mV.
AA battery – 1,5 V.
Telephone line – 60 V.
Electric eel – 650 V.
High frequency TV antenna – 1 to 100 mV.
Contact tram line is 550 V.
Storm cloud – 10 gigavolt.

## Useful tip: how to behave in the field ragged wire?

When the open wire touches the ground, it may be a step voltage. Up to a point it is not very dangerous. It becomes fatal only when changing the path of movement of electricity in the human body.

Step voltage – the voltage step of one person. The feet are a contacts, and the current moves in a closed circuit leg-leg. This is a dangerous condition, but not fatal, as the heart is tiny part of the electricity. If the current will lead to uncontrollable muscle contractions and the man will fall down, will change the path of current flow and will increase by a step voltage. This is a lethal situation. It is by no means impossible to avoid. For this to get out of the danger zone quickly, but very small steps, since the step voltage is directly proportional to the distance between the points of contact. But it is better to jump on one leg out of the affected area.