Do Now (8/26/13): Welcome! 1.Find your seat 2.Write your name on the notecard on your desk.
Brainstorm: 1.What does the word “charge” make you think of? 2.What is the definition of the word “static”? 3.Describe the parts and structure of an atom.
Chapter 20 Static Electricity
Intro Syllabus Course outline BPI webpage Vocab
Electrostatics The study of charges that can be collected and held in one place
With your “elbow partner” come up with examples where charge differences build up in nature, and describe the consequences
Charge Caused by an electron imbalance as electrons move
Atomic Charge In neutral atoms the number of electrons = the number of protons
Charge Opposite charges attract & like charges repel
Charge Conservation electric charge can neither be created nor destroyed.
Charge The charge of an object leaks off into water molecules in air
Charge Charged objects eventually return to their neutral state
Charge Holding a charge is easy on dry days & difficult on humid days
Conductors Materials like metals that allow electrons or charges to move
Common Conductors Copper, silver, gold, aluminum, & graphite
Insulators Materials that will not allow electrons or charges to move easily
Common Insulators Glass, dry wood, plastic, rubber, & dry air
Electron Sink Anything that can absorb lots of electrons
Common Electron Sinks People, Earth, etc
Electroscope A device used to detect electrical charge
Charge Redistribution Conduction Induction
Charge by Conduction Charge by touching a charged body to a neutral body
Charge by Induction Charge by moving a charged body near a neutral body
Charge Separation on Neutral Objects
Do Now (8/27/13): Complete the pre-lab
Do Now (8/28/13): Complete the Drill sheet
Electrical Force Force caused by the attraction or repulsion of charges
Electrical Force Electrical force must be much greater than gravitational force
Coulomb’s Law Force between charges is proportional to charge & inversely proportional to distance between charges
Coulomb’s Law F q A q B
Coulomb’s Law F 1d21d2
Coulomb’s Law F q A q B d 2
F e Formula F e = K q A q B d AB 2
Electric Constant K = 9.0 x 10 9 Nm 2 C 2
Identify another formula that is very similar to the electrical force formula
Gravity Formula F g = G m A m B d AB 2
The magnitude of the force is inversely proportional to the square of the distance
Calculate the electrical force occurring when a ball with a charge of 2.0 x C is 12 mm from another ball with a charge of -3.0 x C:
Calculate the electrical force occurring when a ball with a charge of 3.0 x C is 12 mm from another ball with a charge of -6.0 x C:
Millikens Oil Droplet Experiment
Electron Charge 1.60 x C C = Coulombs
Calculate the force between 2 electrons 8.0 x nm apart:
Calculate the force between the electron & the nucleus of hydrogen: 4.0 x nm apart:
Do Now (8/29/13): Complete the Drill sheet
Do Now (8/30/13): Complete the Drill sheet
A BC d AB = 4.0 mm d BC = 3.0 mm q A = x C q B = 3.0 x C q C = 9.0 x C Calculate: F e on B
A BC d AB = 4.0 mm d BC = 3.0 mm q A = x C q B = 3.0 x C q C = 9.0 x C Calculate: F e on A
A BC d AB = 4.0 cm d BC = 3.0 cm q A = 3.0 x C q B = 3.0 x C q C = 6.0 x C Calculate: F e on C
Calculate the force between 2 particles 1.2 x m apart: q 1 = 4.0 x C q 2 = x C