1. 12/5 Bell Work
How can it be that a man was once married to the sister of his widow?
Hint: What is a widow? Who did he marry first?
married the sister first
Widow’s walk

2. 12/5 Schedule Notes Ch 17.1 “Static Electricity” Work
Coulomb’s Law Worksheet due WEDNESDAY
Finish test
Barbies, Bratz, GI Joe? 5 pts each, can bring in 3
Assignments:
1. Coulomb’s Law Worksheet due WEDNESDAY

3. Electricity and Magnetism
Ch Objective:
Describe how electricity and magnets do work.

4. Ch 17.1 “Charge & Force” Objectives:
Identify particles causing electric charge.
Describe and diagram how objects transfer charge.

5. Static Electricity Intro
Fabric softeners are commonly used because they eliminate static cling. Why do clothes in the dryer get static cling?
Why can walking across a carpeted room be a shocking experience?

6. Electric Charge Kinds of electric charge Negative Positive Neutral
Electric charge: an electrical property of matter that creates electric and magnetic forces and interactions

7. Electric Charge
Electric charge depends on the imbalance of protons (+) and electrons (-).
Features of charge
Neither created or destroyed.
Same charges repel, and opposites attract.
Equal + and – charges = 0

8. Electric Charge The SI unit of electric charge is the coulomb, C.
A proton has a charge of +1.6  10–19 C.
An electron has a charge of –1.6  10–19 C.
The amount of electric charge on an object depends on the number of protons and electrons.
The net electric charge is always a multiple of 1.6  10–19 C.

9. Transfer of Charge Charges can move within uncharged objects.
Charges in a neutral conductor can move without changing the overall charge of the object.
Areas missing those charges now have an induced charge.
Induced charge

10. Transfer of Charge Charge by contact. Charged by friction
Contact charge: touching a charged object to a neutral object
Charged by friction
One material gains electrons (-), and the other loses electrons (now +).
Ex: static cling, walk in socks on carpet
Girl touching a van de graaff generator

11. Electric Force Electric force is caused by…
attraction/repulsion of charged particles
Electric force is responsible for…
friction
lightning
shocks
atomic bonds

12. Electric Force Electric force depends on charge and distance.
The force is proportional to the product of the charges.
Force is inversely proportional to the square of the distance.
Coulomb’s Law
Q in Coulombs
d in meters

13. 12/6 Bell Work
If there are nine players on a baseball team, and three strikes make an out and four balls make a walk, how many outs are there in an inning?
6, 3 for each team

14. 12/6 Schedule Notes Ch 17.1 “Static Electricity”
Static Electricity Lab, finish procedure today
Work
Coulomb’s Law Worksheet due WEDNESDAY
Finish test
Barbies, Bratz, GI Joe? 5 pts each, can bring in 3
Assignments:
1. Coulomb’s Law Worksheet due WEDNESDAY

15. Electric Force Electric force acts through a field.
electric field: the space around a charged object in which another charged object experiences an electric force
Show electric fields by drawing field lines.
Electric field lines point in the direction of the electric force on a positive charge.
The electric field lines around a negative charge point inward.
The electric field lines around a positive charge point outward.

16. Electric Force Electric field lines never cross.
Lines near two like charges point away from each other, and show that the charges repel.
Lines show direction and relative strength of a given charge.
More lines are drawn for greater charges to indicate greater force.
Two positive charges repel each other.
The positive charge is twice as large as the negative charge.

17. 12/7 Bell Work
What common substance is more dense in its liquid form than in its solid?
HINT: What FLOATS when it freezes?
water

18. 12/7 Schedule Notes Ch 17.2 “Current” Static Electricity Lab due TODAY
Work
Finish waves test
Coulomb’s Law Worksheet due WEDNESDAY
Barbies, Bratz, GI Joe? 5 pts each, can bring in 3
Assignments:
1. Coulomb’s Law Worksheet due WEDNESDAY

19. Ch 17.2 Current Objectives:
1. Compare/contrast electrical and gravitational potential energy.
2. Explain what causes electric resistance.

20. Batteries and Appliances
Name five devices that use batteries.
Give reasons why copper is normally used to wire a home for electricity.

21. Voltage and Current
Relating electric and gravitational potential energy
Depend on position
Move from high to low energy
electrical potential energy: the ability to move an electric charge from one point to another

22. Electrical Potential Energy
The electrical potential energy between two negative charges decreases as the distance between them increases.

23. Voltage and Current Potential/voltage difference in circuit
Force increases as similar charges move closer to each other.
SI unit is the volt,
V, = one joule per coulomb
(1 J/C).

24. Voltage and Current Voltage moves across the terminals of a battery.
cell: a device that produces an current by converting chemical or radiant energy into electrical energy
One terminal is positive, and the other is negative.

25. Voltage and Current Voltage sets charges in motion.
Current is the rate of charge movement.
electric current: the rate at which charges pass through a given point
The SI unit of current is the ampere, A.
1 amp = 1 C/s

26. Voltage and Current
Direct current: the charges always move from one terminal to the other in the same direction.
EX: battery
The direction of current is opposite to the direction that electrons move.

27. Electrical Resistance
Resistance causes
internal friction
slows the movement of charges through a material.

28. Electrical Resistance
Resistance can be calculated if current and voltage are known.
Resistance indicates how much the motion of charges within it is resisted because of collisions of electrons with atoms.
Ohms’ law:
The SI unit of resistance is the ohm (Ω)
1 Ω = 1 V/A

29. Math Skills Resistance
Typical car headlights are powered by a 12 V battery. What is the resistance of the headlights if they draw 3.0 A of current when turned on?
1. List the given and unknown values.
Given: current, I = 3.0 A
voltage, V = 12 V
Unknown: resistance, R = ? Ω

30. Math Skills 2. Write the equation for resistance.
3. Insert the known values into the equation, and solve.
R = 4.0 

31. Electrical Resistance
Ranking Resistance
Superconductors = 0 when below a critical temp
Conductors = low
Semiconductors = certain conditions.
Insulators = high
Once a current is established in a superconductor, the current continues even if the applied voltage is removed.
Superconducting magnet

32. Stop Notes

33. Ch 17.3 “Circuits” Objectives:
Describe the two ways that devices can be connected in a circuit.
ID what happens to the energy that charges have in a circuit.

34. Electricity Brainstorm
Inexpensive electrical power is essential. List at least six electrical devices that you have used today.
2. In some strings of Christmas lights, none of the lights work if one light is burned out. What is a possible explanation for this?

35. What Are Circuits? Electric Circuits
The voltage source (battery, outlet, etc.) is always part of the conducting path of a closed circuit.
Without a complete path and voltage source, there is no charge flow and no current.
This is an open circuit.

36. What Are Circuits?, continued
Switches
open and close a circuit
interrupt the flow of charges
allow control

37. What Are Circuits?, continued
Schematic diagrams are used to represent circuits.
schematic diagram: a diagram of a circuit that uses lines to represent wires and standard symbols to represent components
Can be used for all electronic devices.

38. What Are Circuits?
Diagram two light bulbs connected in parallel to 2 batteries…
Draw as picture first.
Change to diagram.
+ terminal of battery is shown with
a longer line.

39. What Are Circuits?
Diagram the pickle battery…

40. Series and Parallel Circuits
2 ways to Connect Circuits
series circuit: parts are joined one after another so that the current in each part is the same
parallel circuit: parts are joined in branches so the potential difference across each part is the same

41. Series and Parallel Circuits
Series circuits have a single path.
Current is the same.
Resistances and voltages may be different.
If one element along the path is removed, the circuit will not work.
Ibattery = I1 = I2 = I3 = ...
Write these in notes!
ΔVbattery = ΔV1 + ΔV2 + ΔV
Rtotal = R1 + R2 + R

42. Series and Parallel Circuits
Parallel circuits have multiple paths.
The voltage across each device is the same.
The current does not have to be the same.
The sum of the currents in all of the devices equals the total current.
A break in any one path does not interrupt the other paths.
Vbattery = V1 = V2 = V3 = ...
Write these in notes!
Itotal = I1 + I2 + I
1/Rtotal = (1/R1) + (1/R2) + (1/R3) + ...

43. Series and Parallel
When light bulbs are connected in series, charges must pass through both light bulbs to complete the circuit.
When light bulbs are connected in parallel, charges have more than one path to follow. The circuit can be complete even if one light bulb burns out.

44. 12/7 Bell Work
What common substance is more dense in its liquid form than in its solid?
HINT: What FLOATS when it freezes?
water

45. 12/7 Schedule Finish Ch 17.3 “Circuits” Ohm’s Law and Power Work Time
V = IR
P= IV
Work Time
Coulomb’s Law Worksheet LATE
Ohm’s Law worksheet due TODAY
Ohm’s Law and Power due WED
Assignments:
Coulomb’s Law Worksheet LATE
Ohm’s Law Practice due TODAY
Ohm’s and Power due WED

46. Electric Power and Energy
Energy and Charges
Some energy is transformed into useful work, (turn motor, play music, etc.)
Some lost heat.
The SI unit for power is the watt (W).
1 W = 1 A  1 V

47. Electric Power and Electrical Energy, continued
Combine P=IV with V = IR, you can calculate the power lost by a resistor.
Electric companies measure energy in kilowatt-hours.
One kilowatt-hour is the energy delivered in 1 h at the rate of 1 kW.
1 kW•h = 3.6  106 J

48. Math Skills
Electric Power When a hair dryer is plugged into a 120 V outlet, the hair dryer has a 9.1 A current in it. What is the hair dryer’s power rating? 1.List the given and unknown values. Given: voltage, V = 120 V current, I = 9.1 A Unknown: electric power, P = ? W

49. Math Skills, continued 2. Write the equation for electric power.
power = current × voltage
P = IV
3. Insert the known values into the equation, and solve.
P = (9.1 A)(120 V)
P = 1.1 × 103 W

50. Fuses and Circuit Breakers
Overloaded (current) circuits
Dangerous…shocks or fire
Might be caused by missing insulation creating a short circuit.

51. Fuses and Circuit Breakers
Overloaded (current) circuits
2 safety measures
fuse: an electrical device that contains a metal strip that melts when current in the circuit becomes too great
circuit breaker: a switch that opens a circuit automatically when the current exceeds a certain value
circuit breaker
car fuse

52. 12/8 Bell Work
Two farmers were discussing their farms when Clem said to John, “My property is a mile square.” John looked at Clem and said, “As a matter of fact, mine is a square mile.” “Then there is no difference,” replied Clem. Is Clem’s last statement correct? Why?
Area is the same, shape doesn’t have to be
John
Clem

53. 12/7 Schedule Review Circuits Equations Ohm’s Law and Power Work Time
V = IR
P= IV
Work Time
Coulomb’s Law Worksheet LATE
Ohm’s Law worksheet LATE
Ohm’s Law and Power due WED
Assignments:
Coulomb’s Law Worksheet LATE
Ohm’s Law Practice due TODAY
Ohm’s and Power due WED

54. Review Circuits and Diagrams
Series
Parallel
Ibattery = I1 = I2 = I3 = ...
ΔVbattery = ΔV1 + ΔV2 + ΔV
Rtotal = R1 + R2 + R
Vbattery = V1 = V2 = V3 = ...
Itotal = I1 + I2 + I
1/Rtotal = (1/R1) + (1/R2) + (1/R3) + ...

55. Calculate the total resistance for 650, 350, and 1000 ohm resistors connected in series.
A 10, 20, and 100 ohm resistor are connected in parallel. Calculate the total resistance.