2 Electrostatics Fe >> Fg Electrostatic Force (Fe) - Study of electricity at restElectrostatic Force (Fe)Attractive OR RepulsiveFe = centripetal force keeping e- in orbitOpposite Charges AttractLike Charges RepelFe >> Fg99% empty spaceElectrons – loosely boundConductors - allow electrons to flow freely (Low e- affinity)Protons & Neutrons – tightly bound in nucleusNucleus –99% of atoms massGold Atom - few valence electrons loosely bound
3 Insulators - do NOT allow electrons to flow freely (High e- affinity)
5 Detecting Charge: Charge Detecting Devices RULES Describe Rutherfords findings in his famous Gold Foil Experiment.
6 3 Methods of Charging Separation of Charge Charging by Contact Friction Conduction Induction by GroundingOutcome Outcome Outcome
7 Units of Charge: Negative Charge Positive Charge Elementary Particles (e) => Coulombs (C)What is the charge in Coulombs for...a) -6eb) +3eCoulombs (C) => Elementary Particles (e)How many extra/fewer e- does object have with charge of...a) -3.2 X10-19Cb) 2.0 X10-19CELECTRON CANNOT BE CUT INTO PIECES!!
8 Conservation of Charge & Charge Transfer: 2 metal spheres touch then separate…ABWhat is the charge on each sphere after contact?What subatomic particle(s) were transferred? From where to where?c) How much charge did A gain in elementary particles and Coulombs?d) How much charge did B lose in elementary particles and Coulombs?+4eBEFORE-6eTotal Charge =What if?ABAFTERTotal Charge =
9 Multistep Charge Transfer MicroCoulomb (μC) :a) How many elementary particles? b) How many MicroCoulombs?-5 μC x 1012eAnalogy: 325cents. How many Quarters?Analogy: 636eggs. How many dozen?Multistep Charge TransferTwo spheres have charges of +3µC and +7µC respectively...What is the charge on each sphere after contact?How much charge was transferred in..µCCeq1.Net Charge =Δq= Δq=2.Net Charge =3.Net Charge =
10 Two 1kg charged objects with charges of +2C and -4C are .5m apart… Coulombs Law:Two 1kg charged objects with charges of +2C and -4C are .5m apart…What is the electrostatic force (Fe) between the objects?What would be force if charges were +2C and +4C?c) What is the gravitational force (Fg) between the objects?Inverse Square Law Relationshipsa) 4rb) 2q1c) 2q1, 3q2d) 3q1, 3q2, 3rFeFeFeFe
11 Electric Field - E-Field Intensity/Strength Electric Field LinesE-Field vs. G-FieldDirection:Rules:What is the electric field strength if a point charge of 2C feels an attractive force of 10N?Given the field strength in part ‘a’, how much force would a proton feels in this field?If the sphere and the point charge are .1m apart, what must be the charge on the sphere?