1. ELECTRICITY

2. Explain the flow of electrons in terms of
• alternating and direct current.
• the relationship among voltage, resistance and current.
• simple series and parallel circuits.
Explain static electricity in terms of
• friction
• induction
• conduction
Construct simple circuits

3. Properties of Electric Charge
Atomic Structure: Composed of three main particles:
Proton
Neutron
Electron

4. Everything is made of atoms.
Things to Remember:
Everything is made of atoms.
Electrons can move from one atom to another atom.

5. Static Electricity The temporary building up of charge on an object.
Some atoms hold e- more tightly than others.
Ex. Your shoes
and Carpet

6. If you walk across a carpet, electrons move from the rug to you (because of friction). Now you have extra electrons. Touch a door knob and ZAP! The electrons move from you to the knob. You get a shock.

8. Static electricity is actually an imbalance in the amounts of positive and negative charges in the surface of an object.

9. TedEd-The science of static electricity

10. Three ways to induce a charge in an object7
Friction
Induction
Conduction

11. Charging by Friction
The frictional charging process results in a transfer of electrons between the two objects that are rubbed together.

12. Involves the charging of one object by another without direct contact.
Charging by Induction
Involves the charging of one object by another without direct contact.

14. Charging by Conduction
involves the direct contact of a charged object to a neutral object.

15. Detecting an Electric Charge

16. Electroscope helps detect electric charge

17. Electrostatics Lab Examples
Bill NYe

18. Electrostatics Lab

19. Electric Current
The constant flow of electrons.

20. Transfer of Electric Charge
Clip
Has to do with the molecular structure of the material
Some materials do not allow electric charge to move freely: Insulators
Ex: glass, rubber
Some materials allow electric charge to move freely: Conductors
Ex: copper, aluminum
Semiconductors:
In their natural state they are insulators: Material can be added to the material to increase its conductivity
Ex: Silicon and Germanium

21. Conductors : Gold, Silver, Copper, Iron, Lead, Salt Water
Conductors : Gold, Silver, Copper, Iron, Lead, Salt Water. Insulators : Plastics, Glass, Dry Air, Wood.

22. Voltage
For electrons to flow there must be a potential difference between to places.
This is called voltage, which is the “Push” that causes electrons to flow.
It’s electrical “Pressure”.
Charges flow from high voltage to low voltage.
Measured in Volts (V).

25. Current
The measure of how many electrons per second are flowing through the wire is the amperage (A).

26. Current and Voltage

27. Resistance
The tendency for a material to oppose the flow of electrons.
Different material have different amounts of resistance to the flow of electrons.
The unit of resistance is ohm.

28. Resistance
Ex: gold, silver, and copper have low resistance, which means that current can flow easily through these materials.
Glass, plastics, and wood have very high resistance, which means that current cannot pass through these materials easily.

29. Resistance in Wires Thick wire Vs. Thin Wire
Thin wires provide more resistance than do thick wires
Resistance also depends on temperature, usually increasing as the temperature increases resistance
Resistance in wires produces a loss of energy (usually in the form of heat), so materials with no resistance produce no energy loss when currents pass through them.

30. Electrical current
The # of e- is called current (unit = Ampere or Amp. )
Electrical current is like the amount or volume of water flowing through the hose.
Water in a Hose
DC in a Wire
Electrical Units
pressure
potential (V)
Volts
volume
current (I)
Amps
friction
resistance (R)
Ohms

32. OHM'S LAW
In a material, the current (I) is directly proportional to the voltage (V) and inversely proportional to the resistance (R).
V=IR

33. Electric Circuits A pathway for electrons to flow.26
A pathway for electrons to flow.
Electrons follow the path of least resistance.

35.                             
Open Circuits
Electrons follow the path of least resistance

36. Closed Circuits
Electrons follow the path of least resistance

37. Series Circuit The current has only one path to follow.
Electrons follow the path of least resistance

38. Parallel Circuits Two or more branches for the current to flow.
Electrons follow the path of least resistance

39. Get a sheet of notebook paper

40. 1) Draw a series circuit that includes a 9-volt battery and a bulb with a resistance of 3 ohms. What is the current?
2) Draw a series circuit that includes a 9-volt battery and a bulb with a resistance of 12 ohms and a bulb with 3 ohms? What is the current?
3) Draw a parallel circuit that contains a 9 volt battery- one pathway with a bulb with a resistance of 3 ohms and one pathway with a bulb with a resistance of 5 ohms. Calculate the current in each branch. What is the total current in the circuit?

41. 1) Draw a series circuit that includes a 9-volt battery and a bulb with a resistance of 3 ohms. What is the current?

42. 2) Draw a series circuit that includes a 9-volt battery and a bulb with a resistance of 12 ohms and a bulb with 3 ohms? What is the current?

43. 3) Draw a parallel circuit that contains a 9 volt battery- one pathway with a bulb with a resistance of 3 ohms and one pathway with a bulb with a resistance of 5 ohms. Calculate the current in each branch. What is the total current in the circuit?

44. a. What is the total voltage across the bulbs?
b. What is the total resistance of the circuit?
c. What is the current in the circuit?
d. What is the voltage drop across each light bulb? 6V 3Ω 2A 2V

45. c. What is the total current provided by the battery?
a. What is the voltage across each resistor?
b. What is the current in each branch?
c. What is the total current provided by the battery?
d. What is the total resistance in the circuit?
The voltage is equal across all components in a parallel circuit. (Therefore, the voltage across R1 is equal to the voltage across R2 which is equal to the voltage across the battery.)
The total current in the circuit is equal the sum of all individual branch currents.
12V
6 A and 4 A
10 A
1.2Ω

46. Investigate the properties of electricity and magnetism.
Lab Goals:
Investigate the properties of electricity and magnetism.
b) Understand the relationship among voltage, resistance & current.
c) Understand how to build simple series and parallel circuits.

47. From Lab: In a series circuit… In a parallel circuit…..
the current through each of the components is the same, and the total voltage in the circuit is the sum of the voltages across each component.
In a parallel circuit…..
the voltage across each of the components is the same, and the total current is the sum of the currents through each component.

48. What happens to the brightness of each bulb in a series circuit as additional bulbs are added? Why?

49. Four identical light bulbs are connected in a circuit as shown below
Four identical light bulbs are connected in a circuit as shown below. The current is greatest through which of the light bulbs?
A 1
B 2
C 3
D 4

50. Dry Cell How do batteries work?
Batteries have three parts, an anode (-), a cathode (+), and the electrolyte. The cathode and anode (the positive and negative sides at either end of a traditional battery) are hooked up to an electrical circuit.                                  
Dry Cell
The chemical reactions in the battery causes a build up of electrons at the anode. This results in an electrical difference between the anode and the cathode. You can think of this difference as an unstable build-up of the electrons. The electrons wants to rearrange themselves to get rid of this difference. But they do this in a certain way. Electrons repel each other and try to go to a place with fewer electrons.

51. Wet Cell  -uses liquids for the electrolytes, as opposed to the dry cell               

54. Review
Series and
Parallel Circuits
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56. Electric Power
The rate at which electrical energy is transferred by an electric circuit.
The SI unit of power is the watt
Joule's Law

57. What is a kilowatt hour? How long you run an appliance.
How much energy is used?
Energy used = Power (kW) x Time (hrs)
E= P x t
To find cost:
Ex: 10¢ per kilowatt hour
E x $

58. 105 V are used to power an appliance that needs 15. 0 amps
105 V are used to power an appliance that needs 15.0 amps. What is the power used?
1575 W =1.575kW
How much energy is used when this appliance is used for 30.0 days- 24hrs a day?
1134 kW -hr
If the power company charges 8¢/Kw-h, what is the cost of the energy above.
$90.72
An electric refrigerator rated 400 W operates 8 hour/day. What is the cost of energy to operate it for 30 days at 8¢/Kw-h?

59. How a Lightbulb Works