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Electrical Charges

Objectives:

Demonstrate that there are two typesof electric charges (after doingexperiments & documentary

research)

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All matter has electrical charges

There are two types of charges:

Positive

Negative

If you have an equal number ofpositives as negatives, makesneutral

Electrical Charges:

+

-

http://www.youtube.com/watch?v=LkIai_KXGxghttp://www.youtube.com/watch?v=LkIai_KXGxg

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There are 2 forces between chargedobjects:

Attraction Repulsion

Opposite charges

Opposites Attract

Same charges

Like repel

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Sphere A is negatively charged.

A

When placed beside sphere B, they attract.

What is the charge on B?

-

B

A

+

OppositesAttract!

POSITIVE

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Three charged spheres are suspendednext to each other.

A B B C

If sphere A isnegativelycharged,

what will happen when sphere A & C aresuspended beside each other?

A C

- -

Attract

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Four charged spheres are suspendednext to each other.

A B B C C D

What will happen if A & D were suspendednext to each other?

+ + + - - +

Repel

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You have three chargedobjects A, B & C in a lab.You record the following

results:Test Observation

Bring A near B They repel

Bring A near C They attract

What would happen if B & Cwere brought together?

They would attract!!!

+ +

+ -+ -

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Electrostatic:

All objects begin neutral& canbecome positivelyor negativelycharged

A positivelycharged object has morepositives than negatives

A negativelycharged object has morenegatives than positives

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Electrostatic seriesis a list that ranksobjects ability to take negative charges

Electrostatic Series:

Rubber

Ebonite

Polyethylene

Cotton

SilkWoolGlass

Acetate

Fur / Hair

Items at toptakenegatives

Items at bottomlosenegatives

Only negativecharges move!Positive charges NEVERmove!!

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Rubber Ebonite Polyethylene

CottonSilk

Wool

Glass

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Your cat rubs against a rubber balloon.What will be the charge on the balloon?Your cats fur?

RubberEbonitePolyethyleneCotton

SilkWoolGlassAcetate

Fur / Hair

Rubber

Fur / Hair

Items at toptakenegatives

Negatives

Rubberballoon

becomesnegative

Cats furbecomespositive

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In a lab, you take a piece of neutral wool& neutral polyethylene & rub themtogether. What will be their charges?

RubberEbonitePolyethyleneCotton

SilkWoolGlassAcetate

Fur / Hair

Wool

Polyethylene

Items at toptakenegatives

Negatives

Polyethyleneballoon

becomesnegative

Woolbecomespositive

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In a lab, you rub a piece ofcotton & ebonite together.Then you rub a piece of silk

& glass together.

RubberEbonitePolyethylene

CottonSilkWoolGlass

AcetateFur / Hair

Cotton is +

Silk is -Theywould

ATTRACT

You then bring the charged piece ofcotton& the charged piece ofsilk

together. What will happen?

+

-

-+

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You rub your hair with a balloon.Explain using words & pictures,why your hair sticks up.

1st Hair & balloon areboth neutral

2nd Rubber balloon takesnegative charges from thehair. So, balloonbecomesnegativelycharged & hairbecomes positivelycharged

3rd Since hair is positive &like charges repel,

hair sticks up!!!

+

+

++

+

_ _

_

_ _

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Two types of charges positive(+) &negative (-)

Opposites Attract

Like Repel

Items at thetopof the electrostaticseries list take negative charges

Only negativecharges move

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Activities

Worksheet #1