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Transcript of Bellwork - amphi.com€¦ · Bellwork Mar. 13, 2018 ... a “particle” with no charge in the...
Chapter 32Electrostatics
Define the following in your notes (from textbook)• Charge:• Ion:• Electrical Force: • Conservation of Charge:• Conductor: [only the (b) definition]• Insulator: [only the (b) definition]
Types of particles • Electron: a negatively charged “particle” in the atom’s shell or outer layers. Its mass is about 1/2000 of a proton and neutron.
• Proton: a positively charged “particle” in the atom’s nucleus.
• Neutron: a “particle” with no charge in the atom’s nucleus.
Structure of the AtomLithium Example (Atomic Number 3)• 3 Protons• 3 Neutrons• 3 Electrons• 99.97% of the atom’s mass is in the nucleus
Electric Charges and Force• Electrons are the particles that transfer (do the moving) in atoms and molecules• Electric charges are conserved • Electric force• Like charges repel• Opposite charges attract
Ions• The result of the net transfer of electrons (ONLY electrons can transfer or move around)• If the atom has more electrons than protons it is a negative ion• If the atom has less electrons than protons it is a positive ion
• Is this carbon atom an ion? What is the charge?
• 6 Protons• 6 Neutrons• 10 Electrons• Yes it is an ion• Negatively charged
Red = ProtonWhite = NeutronBlue = Electron
Example: Carbon Atom
• Is this carbon atom an ion? What is the charge?
• 6 Protons• 6 Neutrons• 2 Electrons• Yes it is an ion• Positively charged
Red = ProtonWhite = NeutronBlue = Electron
Example: Carbon Atom
3 Ways to Charge an Object• Friction: occurs when electrons are transferred by rubbing two objects.
• Contact: occurs when electrons are transferred by direct contact (touching) of two objects.
• Induction: occurs in the presence of a charge WITHOUT physical contact between the two objects.
Triboelectric SeriesAsbestos More PositiveAcetateGlassHuman HairNylonWool FurLeadSilkAluminumPaperCotton SteelWood (Neutral)AmberSealing Wax Hard RubberNickelCopperSilverBrassGold, PlatinumAcrylicPolyethylene (Plastic)Rubber BalloonVinylSiliconTeflonSilicone Rubber More Negative
Electric Polarization• Polarization is a special case of charging by induction
• A charged object seems to be attracted to a neutral object.
Conductors and Insulators• Conductors allow electrons move freely (i.e. aluminum, silver, gold, iron, copper)
• Insulators have tightly bound electrons that cannot move freely
(i.e. plastic, wood, dry skin, cotton and wool cloth, rubber, paper )