Bellwork (2/4/14)Bellwork (2/4/14)

How did you charge the strips in the lab How did you charge the strips in the lab yesterday?yesterday?

By friction (rubbing)By friction (rubbing)

ElectrostaticsElectrostatics

2/4/142/4/14

ElectrostaticsElectrostatics

ElectrostaticsElectrostatics: The study of charges at : The study of charges at restrest

ElectricityElectricity: : any phenomenon any phenomenon associated with electrons (stationary or associated with electrons (stationary or moving) and other charged particles moving) and other charged particles

From the textbook define the From the textbook define the following in your notesfollowing in your notes

Charge:Charge: Ion:Ion:Electrical Force: Electrical Force: Conservation of Charge:Conservation of Charge:Conductor:Conductor: (electricity B definition) (electricity B definition) InsulatorInsulator: (electricity B definition): (electricity B definition)

Types of particlesTypes of particles

Electron:Electron: a negatively charged a negatively charged “particle” in the atom’s shell or outer “particle” in the atom’s shell or outer layers. (mass is about 1/2000 of a layers. (mass is about 1/2000 of a proton and neutron)proton and neutron)

Proton:Proton: a positively charged “particle” a positively charged “particle” in the atom’s nucleus.in the atom’s nucleus.

Neutron:Neutron: a “particle” with no charge in a “particle” with no charge in the atom’s nucleus.the atom’s nucleus.

Structure of the AtomStructure of the AtomLithium Example (Atomic Number 3)Lithium Example (Atomic Number 3)3 Protons3 Protons3 Neutrons3 Neutrons3 Electrons3 Electrons99.97% of the atom’s mass is in the 99.97% of the atom’s mass is in the

nucleusnucleus

Electric Charges and ForceElectric Charges and Force

Electrons are the particles that Electrons are the particles that transfer (do the moving) in transfer (do the moving) in atoms and moleculesatoms and molecules

Electric charges are conservedElectric charges are conserved Electric forceElectric force

Like charges repelLike charges repelOpposite charges attractOpposite charges attract

IonsIons

Due to the net transfer (movement) of Due to the net transfer (movement) of electronselectrons

If the atom has more electrons than If the atom has more electrons than protons it is a protons it is a negative ionnegative ion

If the atom has more protons than If the atom has more protons than electrons it is a electrons it is a positive ionpositive ion

Example: Carbon AtomExample: Carbon Atom

Is this carbon atom Is this carbon atom an ion?an ion?

6 Protons6 Protons 6 Neutrons6 Neutrons 6 Electrons6 Electrons It is not an ionIt is not an ion Not chargedNot charged

Red = ProtonRed = Proton

White = NeutronWhite = Neutron

Blue = ElectronBlue = Electron

Example: Carbon AtomExample: Carbon Atom

Is this carbon atom Is this carbon atom an ion?an ion?

6 Protons6 Protons 6 Neutrons6 Neutrons 10 Electrons10 Electrons Yes it is an ionYes it is an ion Negatively chargedNegatively charged

Red = ProtonRed = Proton

White = NeutronWhite = Neutron

Blue = ElectronBlue = Electron

Example: Carbon AtomExample: Carbon Atom

Is this carbon atom Is this carbon atom an ion?an ion?

6 Protons6 Protons 6 Neutrons6 Neutrons 2 Electrons2 Electrons Yes it is an ionYes it is an ion Positively chargedPositively charged

Red = ProtonRed = Proton

White = NeutronWhite = Neutron

Blue = ElectronBlue = Electron

3 Ways to Charge an Object3 Ways to Charge an Object

Friction: occurs when electrons are Friction: occurs when electrons are transferred by rubbingtransferred by rubbing

Contact: occurs when electrons are Contact: occurs when electrons are transferred by direct contact (touching)transferred by direct contact (touching)

Induction: occurs in the presence of a Induction: occurs in the presence of a charge without physical contactcharge without physical contact

Illustrations on the boardIllustrations on the board

Are on the following two slidesAre on the following two slides [Lab situations][Lab situations] [Charging by contact][Charging by contact]

Triboelectric Series• Acetate ----------------------------------------- More Positive• Glass• Human Hair• Wool • Aluminum• Paper• Cotton • Wood --------------------------------------------- (Neutral)• Hard Rubber• Acrylic• Polyethylene (Plastic)• Rubber Balloon• Vinyl• Silicone Rubber -------------------------------- More Negative

Becomes positively charged

Becomes negatively charged

Electric PolarizationElectric Polarization

Polarization is a special case of Polarization is a special case of inductioninductionWhere a charged object seems to be Where a charged object seems to be

attracted to a neutral objectattracted to a neutral object

Balloon and Water DemosBalloon and Water Demos

-

++

Conductors and InsulatorsConductors and Insulators

Conductors allow electrons move freelyConductors allow electrons move freelyaluminum, silver, gold, iron, copperaluminum, silver, gold, iron, copper

Insulators have tightly bound electrons Insulators have tightly bound electrons cannot move freelycannot move freelyplastic, wood, dry skin, cotton and plastic, wood, dry skin, cotton and

wool cloth, rubber, paperwool cloth, rubber, paper

GroundingGrounding

GroundingGrounding: Allowing charge to move : Allowing charge to move freely to the earth (often making the freely to the earth (often making the object neutral)object neutral)

Electrostatics Notes and Homework Assignment

• Read pages 500-514 and outline in your notes, there will questions about the information on a future Pop Quiz.

• Answer questions #1-25, in complete sentences, on page 515-516 to be turned in. (Due on Fri. 2/7/14)

Triboelectric Series Triboelectric Series

http://www.trifield.com/content/tribo-electrihttp://www.trifield.com/content/tribo-electric-series/c-series/