in physics textbooks electric shock called directional movement of electric charges.However, to compare the strength of the current flow rate of water in the pipe, and the voltage - with its pressure, wrong.It is also wrong to equate the movement of charges to the movement of free electrons. drift velocity of free electrons in the conductors is very small - about 10 mm / s.Electric current - the electromagnetic field distribution in the conductor, or in space.

## What is current?

If the conductor voltage is applied, the electric field it will change.There will as if waiting for the right train in the subway.Here, the train came, the doors opened - we have closed circuit: insert the plug
into the outlet, flipped a switch.People went in motion, they release energy.It can be used: to put, for example, the turnstile, and let cool.

That is, in the electric field has a reserve of energy.If the equilibrium is disturbed field - closed circuit, it opens the door to some of the charges - will current.But his energy is turned into heat or work, the current should feel some resistance.Charge carriers (electrons, ions), "turnstile" (heater, motor, light bulb) is not indignant, and they will work for us regularly.

Thus, current - its ability to produce some action due to energy stored in the electromagnetic field.But the ability to become a work or heat, we must also make voltage: weak scrolls tight tourniquet, even if the way ahead is clear.1 A current at one voltage in one will work in joules and, if it is made within 1 second, the power of 1 W in turn.But zero-voltage current of any work force will not produce - its power is wasted. current very large force with virtually no voltage is possible in superconductors.

## as measured amperage

Force current measured by special devices - ammeter.In a domestic testers also have a multimeter to measure current;on the switch, he denoted by the letters A (amps) or mA (milliamps, 1 mA = 1/1000 A).

To measure current ammeter or tester usual, it is necessary to include in the broken wire.Now there are ammeters, to measure current without breaking the circuit.To do this, either applied to the wire a sensor (Hall sensor), or cover the wire ring ammeter - clamp.In both cases, the measured magnetic effect of the current on which the judge and his strength.

## Action current human

current human action depends on its type - constant or variable - the time of exposure and current.The most dangerous - the current power frequency 50/60 Hz, the same one that in the socket.Its effect on the person is determined considering the exposure time of 1 s. value 50/60 Hz power frequency Historically and technically inefficient.Before it became clear there was a world power, and now it is impossible to change the frequency.

current of 0,1 mA in imperceptible to humans.Current 1 mA causes a slight tingling sensation.3 mA give a severe blow, and after - a fever and other unpleasant sensations;over time, it may be a manifestation of different side effects.10 mA cause seizures, it neotpuskayuschego current.100 mA current is considered to be fatal if the victim for 15 minutes was taken to the intensive care unit.

current through a conductor depends on the applied voltage, as the breakthrough of the crowd to the door - the back of the head.This dependence is expressed by the known Ohm's law.

resistance of the human body can be varied within wide limits, so the rules of electrical charge as small as possible - 1000 ohms.From this is considered safe voltage 12 V or less.

effective measure of protection against electric shock is a safety ground.By analogy with the rushing crowd: it is widely open the back door, and it is free to pass, no one trampled.