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CHAPTER -5CLASS VIIIMrs. Riffat ShaheenBASIC ELECTRICAL COMPONENTS

BATTERY

Batterieshave three parts, an anode (+), a cathode (-), and the electrolyte. The cathode and anode (the positive and negative sides at either end of a traditionalbattery) are hooked up to an electrical circuit. The chemical reactions in thebattery causes a build up of electrons at the anode.An electricbatteryis a device consisting of two or more electrochemicalcellsthat convert stored chemical energy into electrical energy. Eachcellhas a positive terminal, or cathode, and a negative terminal, or anode.WHAT IS A BATTERY???WHAT IS A CELL BATTERY???

The Nickel Cadmium (NiCd) battery.The Nickel-Metal Hydride (NiMH) battery.The Lead Acid battery.The Lithium Ion battery.The Lithium Polymer battery.

RESISTORSAresistoris a passive two-terminal electrical component that increases electrical resistance of a circuit element. The main function is to reduce the flow of electricity in a circuit. In electronic circuits,Resistorsare used to reduce current flow, adjust signal levels, to divide voltages, bias active elements, and terminate transmission lines, among other uses.

CapacitorsA basic capacitor has two parallel plates separated by an insulating materialA capacitor stores an electrical charge between the two platesThe unit of capacitance is Farads (F)Capacitance values are normally smaller, such as F, nF or pF

CapacitorsBasic capacitor construction

Dielectric materialPlate 1Plate 2The dielectric material is an insulator therefore no current flows through the capacitor

CapacitorsStoring a charge between the platesElectrons on the left plate are attracted toward the positive terminal of the voltage sourceThis leaves an excess of positively charged holesThe electrons are pushed toward the right plateExcess electrons leave a negative charge

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CapacitorsTypes of capacitorsThe dielectric material determines the type of capacitorCommon types of capacitors are:MicaCeramicPlastic film

CapacitorsSome capacitors are polarised, they can only be connected one way aroundElectrolytic capacitors are polarised

CapacitorsVariable capacitors are used in communication equipment, radios, televisions and VCRsThey can be adjusted by consumers by tuning controlsTrimmers are internal adjusted capacitors that a consumer cannot adjust

CapacitorsThese variable capacitors would be difficult to squeeze into your mobile phone and iPodCurrent technology uses semi-conductor variable capacitors called varactors (varicaps)

Inductor An inductor is about as simple as an electronic component can get -- it is simply a coil of wire. It turns out, however, that a coil of wire can do some very interesting things because of themagnetic properties of a coil.

In some ways, inductor is opposite of capacitor. The capacity of an inductor to store magnetic energy is called inductance.

Joseph HenryUnit of inductance Henrys (H) is named after himMicheal FaradayUnit of capacitance of capacitor Farady (F) is named after him

TRANSFORMERThis is an electrical device used to increase or decrease the value of alternating current.

Other Electrical componentsDiodeLight Emitting Diode (LED)A diode is a semiconductor device that controls the flow of current in circuit to only one direction.

An LED is a diode that emits the light of particular frequency when current is passed through it.

FUSE JUMPERS

Inelectronicsandelectrical engineering, aFUSEis a type of low resistanceresistorthat acts as asacrificial deviceto provideover currentprotection, of either the load or source circuit. Its essential component is a metal wire or strip that melts when too much current flows through it, interrupting thecircuitthat it connects.Short circuits, overloading, mismatched loads, or device failure are the prime reasons for excessive current. Fuses can be used as alternatives tocircuit breakers.

Jumpers are small devices that are used to control the operation of hardware devices directly, without the use of software. A jumper is a mechanical switch that is easily modified by hand.

RESEARCH WORKWHAT IS A UPS?WHAT IS ELECTROMAGNETIC INDUCTION?HOW DOES A ROBOT WORK ???