ElectricityElectricity

RecallRecall

ElectronElectron: negatively charged : negatively charged fundamental particlefundamental particle

ProtonProton: positively charged : positively charged fundamental particlefundamental particle

Static electricityStatic electricity: build up of charge: build up of charge

ElectricityElectricity: flow of electrons: flow of electrons

Electrons and the GreeksElectrons and the GreeksThe ancient Greeks noticed that The ancient Greeks noticed that rubbing amber could cause it to rubbing amber could cause it to attract bits of straw attract bits of straw

The name we use for this type of The name we use for this type of attraction, attraction, electricityelectricity, comes from , comes from the Greek word for amber, the Greek word for amber, electronelectron

Key concepts about chargeKey concepts about chargeThere are two electrical charges:There are two electrical charges:

– –and+and+

Electrons have a - charge and are free Electrons have a - charge and are free to move in and between certain types of to move in and between certain types of materialsmaterials

Protons have a + charge and cannot Protons have a + charge and cannot movemove

The The flow of electronsflow of electrons is called electricity is called electricity

Most objects are Most objects are neutralneutral, because , because they have an equal number of + they have an equal number of + and – charges/electronsand – charges/electrons

When 2 neutral objects are When 2 neutral objects are rubbed together they each get an rubbed together they each get an opposite chargeopposite charge

The Law of Electric ChargesThe Law of Electric Charges says says that opposite charges attract, like that opposite charges attract, like charges repelcharges repel

+ and – charged objects also + and – charged objects also attract most neutral objectsattract most neutral objects

Attract: cling togetherAttract: cling together

Repel: push apartRepel: push apart

Amber: yellow-orange Amber: yellow-orange

fossilized tree resin -fossilized tree resin -

often containing insectsoften containing insects

?

•What is the charge on the mystery box?

Attraction

•The object could be neutral or positive

?

•What is the charge on the mystery box?

Attraction

•The object could be neutral or negative

?Repulsion

•What is the charge on the mystery box?•It MUST be positive

?Repulsion

•What is the charge on the mystery box?•It MUST be negative

+++

What is the charge on the pith ball?

What happens when webring a charged rod near?

ElectroscopesElectroscopes

A device that can detect the charge on an A device that can detect the charge on an objectobject

Examples: Metal Leaf ElectroscopeExamples: Metal Leaf Electroscope

Your TurnYour Turn

Read and make a small note on Read and make a small note on – page 470 on page 470 on Electrostatic Paint SprayersElectrostatic Paint Sprayers

Page 471 Page 471 – Q: 4-7 Q: 4-7