Electricity Basics


Иностранные языки, филология и лингвистика

Electricity is mde by converting some form of energy into flowing electrons t the power plnt. The type of power plnt depends on the source of energy used: therml power col oil gs nucle r underground stem solr power photovoltic kinetic power wter wind nd chemicl power fuel cell. This system enbles power plnts I nd end users to be connected together. Wtt W is unit mesure of electric power tht depends on mps nd volts.



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7 билет.  Text “Electricity Basics”

Electricity is something we do not notice until we do not have it. However, few

people understand what it is and still fewer can explain it. Let us try it anyway.

So, what is electricity? Electricity is simply a movement of charged  particles

through a closed  circuit. The electrons, which flow through this wire, carry a negative

charge. A lightning discharge is the same idea, just without the  wire.

 Electricity is made by converting some  form of energy into flowing electrons

at the power plant. The type of power plant depends on the source of energy used:

thermal power  (coal, oil, gas, nucle ar, underground steam), solar power

(photovoltaic),  kinetic power  (water, wind) and  chemical power  (fuel cell).  I

After it is made, electricity is sent into a system of cables and wires called a

transmission grid.  This system enables power plants I and end users to be connected


 The basic notions in electricity include the following.

An Amp (A) is a unit measure of amount of  current in a circuit. An ammeter

permits the current to be measured.

 The pressure that forces the cu rrent to flow is measured in  Volts  (V). A

transformer is used to change the voltage of electricity. This allows  electricity to be

transmitted over long distances at high volta ges, but safely used at a lower voltage.

 A  Watt (W) is a unit measure of electric power that depends on amps and

volts. The more watts the bulb uses the more light is produced. Watts = Volts x Amps.

 An Ohm (O) is a unit measure of materials  resistance to a flowing current. The

filament  in this light bulb glows because its high  resistance  makes it hot. Low

resistance of the support wires does not let them glow. The glass has  a resistance so high

that it does not allow the current to move th rough it - this property  makes glass a good


 There are two different kinds of  electrical current. One is called  direct

current  because electrons are made to move in one direction only. It is usually

abbreviated to DC. This kind of electricity is produced by a battery.

 AC Stands for alternating current, which is generated by power station for

domestic and industrial use. The wires in the centre of the  generator rotate past the

North and the South poles of the magnet. This movement forces  the electrons in the

circuit to reverse the direction of their flow. The number of these alterations (or

cycles) per second is known as frequency.

 As domestic supply requires alternating current it is therefore necessary to

change it to direct current insi de most electrical appliances. A  rectifier  allows AC to

be converted into DC.

 Power stations are designed to provid e electrical energy to large housing

developments. This causes  the necessity to transmit  power from its source, the

generating station, to wherever it is required for use,  which maybe far away, with

minimal energy losses. It is cheaper and easier to carry a very high voltage but low

current, over long distances. It can be done w ith the help of thinner overhead conductor

wires, with an  air gap between them to  act as an insulator.   

 A transformer is used to increase or decrease the voltage of an electric power supply.

This is a static machine since it  has no moving parts. It consists of two coils of wire that

are wound around a  soft iron core., Th e coils are called windings , one is the  primary,

or input winding, and the other is the  secondary, or output winding.

 When current passes through the primary winding, a magnetic field is created

around the iron core, which induces a voltage in the secondary winding. If the number of

turns in the secondary winding is greater than that in the primary winding it is a step-up

transformer and the output voltage is greater  than the input voltage. And vice versa, a

step-down transformer enables the input voltage to be reduced.

 A device, which allows an electrical charge to be build up and stored for

some time is known as a  capacitor (or a condenser).  A simple capacitor is made from

two metal plates (electrodes), which are separated by an insulator such as air, paper or mica

(the dielectric).


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