What is electricity?
The phenomenon of the orderly and directed movement of charged particles in substances, which, in fact, called electric current, in nature has always existed. In metals these charged particles – electrons - contribute to the heating of conductors. In the charged electrolyte to move ions, changing its chemical composition. In all cases, the conductors creates a magnetic field.
Electricity all the time present in the air. Called atmospheric electricity. Observed in a thunderstorm, lightning is a natural electrical spark discharge. Current can develop even biological organisms. Electric rays, electric eel use the accumulated potential of several hundred volts for self-protection. In General, the currents play a significant role in all life processes in living beings.
After we studied the properties of electric current and it learned to get a variety of ways, electricity has gained wide practical application in our lives. Today human activities are unthinkable without electricity.
Electrical energy is produced in traditional hydroelectric power plants, power plants, modern nuclear power plants and using alternative energy sources. The resulting electric current – AC. It goes to a transformer substation located in the vicinity. Here is an increase in the AC voltage, to minimize transmission losses over long distances. On the other end of the transmission lines through step-down transformers voltage is reduced to values required by the consumer. Basically it is a three-phase current with voltage of 380 V. In the apartment and the rural house is supplied single-phase AC voltage of 220 V. the Second wire is zero.
Alternating electric current passing through the circuit all the time changes its magnitude and direction. Or, keeping the direction unchanged, changes only in magnitude. Change the magnitude and direction takes place in cycles, with periods with a certain repetition frequency. The number of periods per second is called frequency alternating current and is measured in Hertz. In most countries, including in Russia, use current frequency of 50 Hz (in USA and Canada is 60 Hz).
AC work all the appliances. DC sources are batteries and batteries. Also get constant current, rectifying the AC special devices.