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CHAPTER 7 : ELECTRICITY7.1 : Electrostatics7.2 : Electricity

7.3 : Measuring Electricity

7.4 : Ohms Law7.5 : Concept of Series & Parallel

Circuit 7.6 : Current, Voltage & Resistance in

a Series Circuit

7.7 : Current, Voltage & Resistance in a

Parallel Circuit 7.8 : Magnestism7.9 : Electromagnetism

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7.1 : ElectrostaticsStructure of an ATOM

Atom : thesmallest particlein an element

Has nucleus(proton +neutron) andelectrons

Differentelements have

different numberof electrons,protons andneutrons in theiratoms

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7.1 : ElectrostaticsProducing Static Electrical Charges

Electrostatic :The study ofstatic electricalcharges(+ve & -ve)

When 2 objectsare vigorouslyrubbed againsteach other, 1

object receiveselectrons & theother loseselectrons

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7.1 : ElectrostaticsProducing Static Electrical Charges

A charged objectattractsunchargedobjects

Objects with likecharges repeleach other

Objects withunlike chargesattract eachother

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7.1 : ElectrostaticsProducing Static Electrical Charges

Electroscope :To detectstaticelectricalcharges

Gold leaf of anunchargedelectroscopediverges

when achargedobject isbrought nearits metal cap

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7.1 : ElectrostaticsEveryday Phenomena Related to Static

Electrical Charges Lightning :

Due to static electrical charges in thethunderclouds escaping from cloud tocloud/ a cloud to the earth producing

bright flashesFriction between water molecules in the

clouds & the air molecules produces alarge quantity of electrical charges in the

cloudsLightning is produced when the electrical

charges in the clouds escape & producesbright flashes of light & loud sounds ofthunder

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7.1 : ElectrostaticsEveryday Phenomena Related to Static

Electrical Charges Lorry carrying petrol storage tank :

Lorry petrol tanker is in danger ofcatching fire because petrol flammable

As the lorry moves along a road, frictionbetween the lorry & air produceselectrical charges on the lorry

But the rubber tyres of the lorry preventthe charges from escaping to the earth

A metal chain attached to the lorrytouches the road so that electricalcharges are conducted by the metal chainto the ground

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7.1 : ElectrostaticsEveryday Phenomena Related to Static

Electrical Charges Car spark plugs :

Car spark plugsare use to ignitethe petrol

vapour in the

car engineWhen the car

engine starts,static electricalcharges jump

across the gapat the end of thespark plug,producingsparks to ignitethe fuel in the

engine

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7.1 : ElectrostaticsEveryday Phenomena Related to Static

Electrical Charges Aeroplane :

Aeroplane flyingthrough the airbuilds up static

electrical chargeon its body dueto friction withthe air

When aeroplanelands, its specialconductive tyresare able toconductelectricalcharges to the

ground

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7.1 : ElectrostaticsEveryday Phenomena Related to Static

Electrical Charges Photostat machine :

Rolling cylinderin the machinebecomes

charged withstatic electricalcharges & thepaper rolls out isalso charged

Charge paperattracts carbonpowder to it toproduce a copyof the originaldocument

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7.1 : ElectrostaticsEveryday Phenomena Related to Static

Electrical Charges Dry hair :

Dry hair stands upwhen it isvigorously combed

on a dry day

When the hair iscombed, frictionbetween the hair &the comb produces

static electricalcharges As the hair has like

charges, the strandsof hair repel one

another & stand

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7.1 : ElectrostaticsSafety measures for Electrical Charges

Care must be takenwhen dealing withelectrical charges forthey can injure/kill/damage

Examples :

Tall buildings

installed withlightning conductorsto prevent thebuildings from being

damaged by lightning

People living onmountains should notuse zinc sheets asthey attract lightning