1. Pre-Test
Arrange proton, neutron, and electron in order of mass lowest to highest.
What is the charge on each?
Describe the behavior of like and unlike charges.
How do the number of electrons and protons in an atom compare?
What is the net charge on a normal atom?
What is an ion? How are they created?
Estimate how many electrons are in your pencil.
Define conductor and insulator.

2. Atom Basic Review
Protons and neutrons are in the nucleus, surrounded by electrons. + –
Proton (positive charge) +
neutron (neutral) –
electron (negative charge)
atom
nucleus

3. Neutron > Proton >>>>>> Electron
Relative Masses
Neutron > Proton >>>>>> Electron

4. How many electrons and protons are shown in the atom above?
Normal neutral atoms have equal numbers so TOTAL charge = 0

5. The Rules of Static Electricity Opposites attract; Likes Repel+ + - +
-The total amount of charge is conserved

6. Some materials hold electrons more tightly Holds Electrons Strongly
Electron affinity
Some materials hold electrons more tightly
Holds Electrons Strongly
Sulfur
Brass
Copper
ebonite
wax
silk
lead
fur
wool
glass
Hold Electrons Weakly

7. Charging By Friction Simplest way to create a charge
Tear electrons away from one object onto another

10. Conductors have “sea of electrons”
Electrons move easily in conductors but are stuck with their atoms in insulators.

11. Induction: A Neutral conducting object gains or loses electrons when a charged object is brought close to it.

12. Electric force : Attraction or repulsion push/pull on charged objects
Stronger if the charge is greater
Stronger if the objects are closer

13. Use you graph to predict what the force would be at 6 mm:
Graph the following force data for two charged objects separated by changing distance:
Distance (mm)
Force (N) 1
243 3 27 5 10 7 9
Use you graph to predict what the force would be at 6 mm:

14. Electric Field: Area of lines that show the direction of force on any nearby positive charges

15. Draw the electric field for a positive charge and a negative charge:
Electric Field: Area of lines that show the direction of force on any nearby positive charges
Draw the electric field for a positive charge and a negative charge:

18. Electrons can move through the bulb in either direction
Light Bulb
Electrons can move through the bulb in either direction

19. To create a flow of electrons in the wires we must have;
A source of voltage (electric pressure) for the electrons
A complete conducting pathway for the electrons (complete circuit)

20. Potential Difference (also called Voltage) : Energy electrons lose/gain from a power supply
Current tells us how many electrons are moving between two points per unit of time

21. Water-Circuit Analogy Water Pressure = Voltage
Pipe = Wire
Water Flow = Current
Water = electrons
Water Pressure = Voltage
Pump = ?

22. Resistance: Opposition to the flow of charges
Units: Ohms Ω
Conductors: Low Resistance
Insulators: High Resistance

24. Ohm’s Law : V = IR

25. Paul’s air conditioner runs off the 120 Volt power supply
Paul’s air conditioner runs off the 120 Volt power supply. If it draws 3 Amps of current, what is the resistance of the air conditioner unit?

26. If a wire has a resistance of 1. 94 Ω and is connected to a 9
If a wire has a resistance of 1.94 Ω and is connected to a 9.0 V battery, how much current will travel through the wire?

27. The heating element in a toaster has a resistance of 30 Ohms
The heating element in a toaster has a resistance of 30 Ohms. If the heating element draws 7.33 Amperes (Amps), what is the voltage across the toaster ?