3. Basic Electricity Info... All electricity is energy that results from the movement of electrons.

4. All matter is made up of positive and negative charges The negatives charges (electrons) can move freely and this movement creates… ELECTRICITY!

5. Electric current is the movement or flow of electrons. CIRCUIT is the PATH the electricity travels on.

6. Most of the time, the + and – charges cancel each other out. Most matter is neutral

7. Static Electricity Static electricity is the buildup of charges on an object The word static means not moving

8. How can electric charges build up on an object? Friction Conduction Induction

9. When charges on an object are rearranged without physical contact, it has been charged by induction.

10. Conductors A conductor is a material through which electric charges move easily Examples of conductors: Metals such as copper, aluminum, gold, silver

11. Insulators An insulator is material through which electric charges cannot move easily Examples: plastic, rubber, wood, glass and sand

12. Static Discharge The loss of static electricity as charges move off an object is called static discharge

13. Lightning! A giant electric spark, called lightning, is the result of static discharge created in a cloud.

14. Only some lightning reaches Earth and it can be VERY dangerous and can cause property damage.

15. The wind rubs together the water molecules and particles of matter in the clouds This friction causes static electricity to build up in the cloud

16. The electrons collect in the lower part of the cloud They induce positive charges from the ground below.

17. Who is this? Clues: Inventor Lightning rod Ben Franklin A lightning rod conducts an electric charge from the cloud directly to the ground.

18. Electricity ~ Mouse and Cheese Analogy The negative charges (mice) will do work in order to get to the positive charges (cheese ).

19. Electricity ~ Mouse and Cheese Analogy The mouse wants to get to the cheese, but there is no path.

20. The Mouse Cheese Circuit The mouse (electron) will gladly do work to get to the cheese (proton)

21. The Mouse Cheese Battery This is the mouse-cheese version of a D cell and an AA cell Which is which?

22. The Mouse Cheese Battery Both the D cell and the AA cell produce 1.5 volts. What is the difference? Answer: The D cell will last longer

23. Real Batteries Both the D cell and the AA cell produce 1.5 volts. What is the difference? Answer: The D cell will last longer

24. Electrochemical Cells Electricity can be generated by a chemical reaction An electrochemical cell changes chemical energy into electrical energy

25. Electric Current Measurement Each month your family receives an electric bill. How does Con Ed determine how much money you owe?

26. CURRENT ~ is the rate of flow of charges

27. Voltage - causes current to flow through an electric current

28. VOLTAGE ~ The amount of work that each charge will do as it goes through the circuit.

29. RESISTANCE ~ the opposition to the flow of charge. Any appliance that asks the charge -- to do work will slow the charge down

30. A wire’s resistance depends on: The kind of material it is made of The length The temperature

31. What do you think are the TOP FIVE Power RATINGS for Common Appliances? 1. 2. 3. 4. 5.

32. NAME this SCIENTIST! Who invented the light bulb? Thomas Edison

33. How does a light bulb work? Electrons flow through a wire and heats up the chemicals in the filament.

34. Light Bulbs When the electrons reach the filament, its resistance is so great that the electric energy is converted into heat and light energy.

35. Current The symbol for current is the capital letter I The unit measure for current is amperes or amps Current is measured with an ammeter

36. Resistance The symbol for resistance is R Resistance is measured in units called ohms

37. Voltage Voltage is measured in volts The symbol for volt is V Voltage is measured with a voltmeter

38. Electroscope An electroscope is an instrument used to detect an electric charge

39. Ohm’s Law Ohm’s Law states that the current in a circuit is equal to the voltage divided by the resistance

40. Ohm’s Law Where: V is the Voltage measured in volts I is the Current measured in amperes R is the resistance measured in Ohms

41. Sample Problem A nine volt battery supplies power to a cordless curling iron with a resistance of 18 ohms. How much current is flowing through the curling iron?

42. Solution 1.) Since V(Voltage) and R(Resistance) are known, solve for I(Current) by dividing both sides of the equation by R.

43. Solution 2. The R's on the right hand side of the equation cancel.

44. Solution 3.) I is then left in terms of V and R

45. Solution 4.) Substitute in the values for V(Voltage) and R(Resistance).

46. 5.) Solve for I (Current)

47. Why can a bird sit on a power line? When a bird sits on a power line, both feet are on the line. There is no potential difference between the feet.

48. If one leg is on the ground and the other one is on the power line, then there are potential difference between these two legs.

49. Therefore, there is a flow of charge and eventually the chicken will be fried…get it?

50. Sample Problem A 110 volt wall outlet supplies power to a strobe light with a resistance of 2200 ohms. How much current is flowing through the strobe light?

51. Sample Problem Answer: