1. Charge Current (charge flow) Voltage Resistance Ohm’s Law
Intro to Electricity
Charge
Current (charge flow)
Voltage
Resistance
Ohm’s Law
Intro to Electricity: will cover …
Charge — the fundamental “stuff” that “makes” electricity
Current = moving charge
Voltage = the force that makes charge move
Resistance = the “friction” that keeps charge from moving
Ohm’s Law = relation among the variables

2. Intro to Electric Charge
Electric Catfish
Long before anyone even had a word for “electricity” what an atom or electron was, inquisitive people knew that something “shocking” could be produced by electric fish in the Nile river rubbing certain objects together.
The Greeks knew that they could “charge” amber (mineralized tree sap) by rubbing it with cat fur (don’t ask) and pick up small, light objects like feathers (demo by rubbing amber on necktie & pick up small feather)
First serious research on electricity by William Gilbert c1600 who coined term “electricus” based on “ēlektron” —Greek for amber
No one knew what charge was — maybe an invisible fluid — but they could still move it around and study it.
1) Some materials transfer charge, and others don’t – as you’ll find out in the uDu!
2) Charge makes things stick together or push apart
3) Lots of charge can produce a painful shock
Amber: Greek “ēlektron”

3. Intro to Electric Charge
Fun FYI: Amber room started in 1701 and expanded over the decades. Amber panels backed with mirrors and gold leaf. Ended up in Imperial Russia. Stolen by Nazis and never found. This room is a re-creation. An absolute nightmare to dust – the more you wipe it to remove dust, the more dust it attracts!
Amber Room in Catherine Palace, Russia

4. Intro to Electric Charge
Charge Transfer uDu …
Let’s move some charge around …

5. Charge Transfer uDu
Objective: You are a packaging engineer, and you want to build a device that uses static electric charge to pick up those annoying foam peanuts from the floor. You plan to build a machine that rubs two materials together to transfer the most charge and therefore produce the strongest static electric force. You must find and document the best choice of materials.

6. Charge Transfer uDu Materials: •
4 insulating rods (clear acrylic, hollow polyvinyl chloride, white nylon and maple wood)
4 cloths (blue silk, gray wool, patterned cotton and polyester felt)
Charge-O-Meter (copper pipe supported on sharp spindle — which means you’re not going to screw around with it)

7. Charge Transfer uDu Methods: •
You will rub the the rods with the cloths to charge them. YOU have to design and standardize the technique.
You will use your Charge-O-Meter to measure how much charge a rod acquires by measuring how strongly the rod and the Charge-O-Meter attract each other. YOU have to figure out how to measure strength of attraction.
YOU record your Methods on YOUR worksheet.

8. Charge Transfer uDu Results:
Complete the 4 x 4 table that summarizes your results. That is, record the strength of attraction as measured by YOU when each rod is rubbed by each cloth. Choose the best combination for your peanut picker-upper based on YOUR results.
AMOUNT of CHARGE
Wool
(gray)
Poly
(solid color)
Cotton
(money print)
Silk
(dark blue)
Wood
PVC (hollow)
Acrylic (clear)
Nylon (white)

9. Charge Transfer uDu Conclusions: Some rods got charged others didn’t
Some cloths worked with some rods but not others
YOU could figure the combination that produced the strongest attraction without knowing WHY rubbing produces attraction. Examples?
AMOUNT of CHARGE
Wool
Poly
Cotton
Silk
Wood
PVC
Acrylic
Nylon

10. Intro to Electric Charge
Electric Kiss
Machinery Belt
Like you in the uDu, people could build fancy machines that transfer LOTS of charge — still basically by rubbing materials together, without knowing why they worked (Examples 1 & 2). Sometimes lots of charge was transferred accidentally by machinery. Drive belts produced harmful shocks or sometimes set sawdust on fire (which still happens in the occasional Amish shop). That’s bad, but it inspired the …
Hauksbee
Generator

11. Intro to Electric Charge
van de Graaf
Generator
CHARGE BASICS
Charge can move
Two types of charge (positive & negative)
Like charges repel, opposites attract !
Negative
charges
… van de Graaf generator (and other devices) that allowed basic discoveries of the properties of charge.
DEMO – pie tins on top of vdG: (don’t spend much time – Mr. Reber has done all of this)
Charge Basics:
Charge can move
Two types of charge: “positive” & “negative” (for lack of better terminology)
Like charges repel, opposites attract
Now let’s develop rules for the movement of charge using movement of water as an analogue …

12. Flo Flow ! Flo’s Flows uDu: Water Flow = ————————
Tubing Resistance
• Low
• High
Flow
1 Small
2 Medium small
3 Medium large
4 Large
Flo
Wide
Tube
Flow
Bucket Height
• High
• Low
Narrow
Tube !
Definitions: Flo versus Flow …
Amount of Water
Flow = ————————
Time
Objective: Predict & confirm effect of bucket height and tubing diameter on the rate of water flow.

13. Flo’s Flows uDu: Water
Tubing Resistance
• Low
• High
Flow
1 Small
2 Medium small
3 Medium large
4 Large
Wide
Tube
Bucket Height
• High
• Low
Narrow
Tube
Discover law of charge flow by analogy to fluid flow:
Objective: Predict & confirm effect of bucket height and tubing diameter on the rate of water flow.
300: Will do water flow version ONLY and as a whole class (next slide)
310: Half of class will do water, half will do Plinko (2nd slide ahead)
Objective: Predict & confirm effect of bucket height and tubing diameter on the rate of water flow.

14. ! Flo’s Flows uDu: Water Flow 1 Small 2 Medium small 3 Medium large
Tubing Resistance
• Low
• High
Flow
1 Small
2 Medium small
3 Medium large
4 Large
Wide
Tube
Bucket Height
• High
• Low
Narrow
Tube !
Predictions:
Discover law of charge flow by analogy to fluid flow:
Objective: Predict & confirm water flow based on bucket height and tubing diameter
300: Will do water flow version ONLY and as a whole class
310: Half of class will do water, half will do Plinko (next slide)
Water Flow
(1 – 4)
HEIGHT Lo Hi
RESISTANCE

15. Flo’s Flows uDu: Plinko
Marble Diameter
• Big
• Small
Flow
1 Small
2 Medium small
3 Medium large
4 Large
Board Height
• High
• Low
310 Only !
Predictions:
For 310: Have half the class do uDu with water on front of ladder & half do Plinko version on back of ladder.
Marble Flow
(1 – 4)
HEIGHT Lo Hi
SIZE
Small
Big

16. uDu ! Flo’s Flows uDu: Water Flow 1 Small 2 Medium small
Tubing Resistance
• Low
• High
Flow
1 Small
2 Medium small
3 Medium large
4 Large
Wide
Tube
Bucket Height
• High
• Low
Narrow
Tube !
Predictions:
Have Ss set up buckets (graduated ½ gallon milk containers), tubes & catch basin; design flow measurement (volume of water divided by time); collect data & record results. Flow can be started by starting siphon with syringe. Ss will have to coordinate timing including when to start and stop.
For Plinko, Ss will set board on lowest and middle stringer on back of ladder, and time completion for large and small marble (high & low resistance). Here, Ss will have to make multiple measurements because of large random errors in path of marble.
Water Flow
(1 – 4)
HEIGHT Lo Hi
RESISTANCE

17. ! A. F = P × R B. F = P / R C. F = R × P D. F = R / P
Flo’s Flows uDu: Water !
Flow …
• Increases as height or pressure ________
• Decreases as resistance ________
YLDOI: Which math formula works?
A. F = P × R
B. F = P / R
C. F = R × P
D. F = R / P
Results:
Flow …
Increases as pressure increases
Decreases as resistance increases
So: Flow = Pressure / Resistance
Water Flow
(1 least – 4 most)
HEIGHT Lo Hi
RESISTANCE
2.5 4 1

18. A. F = P × R B. F = P / R C. F = R × P D. F = R / P !
Flo’s Flows uDu: Water
Flow …
• Increases as height or pressure ________
• Decreases as resistance ________
YLDOI: Which math formula works?
A. F = P × R
B. F = P / R
C. F = R × P
D. F = R / P !
Results:
Flow …
Increases as pressure increases
Decreases as resistance increases
So: Flow = Pressure / Resistance
Water Flow
(1 – 4)
HEIGHT Lo Hi
RESISTANCE
2.5 4 1

19. Flo’s Flows uDu: Electricity
WATER
ELEC’Y
ABBR
UNIT
DEWG
RESIST-ANCE
Current
Number of electrons per second Q
Volt
Pressure
Force pushing water
Charge
Number of electrons I
Ohm
Volume
Amount of water V
Coulomb
Flow
Amount of water per second
Voltage
Force pushing electrons R
Ampere
“Amp”
Re-arrange the columns in yellow to match the columns in white.
Distribute (one set per table) and use “game board” & pieces to re-arrange the columns in green to match the abbreviations (and pictures). Terms are in correct COLUMN but wrong ROW. Look for similarity of terms.

20. ! Q I V R WATER ELEC’Y ABBR UNIT DEWG Volume Charge Coulomb Flow
Amount of water
Charge
Number of electrons Q
Coulomb
Flow
Amount of water per second
Current
Number of electrons per second I
Ampere
“Amp”
Pressure
Force pushing water
Voltage
Force pushing electrons V
Volt
Resistance R
Ohm
COPY INDICATED COLUMNS INTO NOTEBOOK …
Names FYI: Charles-Augustin Coulomb, Andre-Marie Ampere, Alessandro Volta, Georg Ohm

21. F = P / R __ = __ / __ Flo’s Flows uDu: Water Water Flow:
Charge Flow: Ohm’s Law
__ = __ / __
Use table to figure out formula for flow of electricity: I = V / R (Ohm’s Law)
Other forms: V = I * R ; R = V / I

22. Flo’s Flows uDu: Charge
Water Flow:
F = P / R
Charge Flow: Ohm’s Law
I = V / R
V = I × R
R = V / I !
Use table to figure out formula for flow of electricity: I = V / R (Ohm’s Law)
Other forms: V = I * R ; R = V / I
Assign “Flo’s Flow Woes” worksheet
Do “Ohm’s Law” labette

23. Flo’s Flow Woes
Flo’s Flower shop has a frequently frustrating flow problem. Flo waters her greenhouse plants using a hose attached to a water tank on the roof. Unfortunately, Flo’s flow isn’t enough for her parched plants.
1. Flo first measures the flow she gets now by sticking the hose in a 50 gal drum and measuring how long it takes to fill. If it takes 25 minutes to fill the drum, what is Flo’s flow rate? (Remember: flow = volume / time)
Worksheet answers – Do when needed

24. Flo’s Flow Woes
Flo’s Flower shop has a frequently frustrating flow problem. Flo waters her greenhouse plants using a hose attached to a water tank on the roof. Unfortunately, Flo’s flow isn’t enough for her parched plants.
1. Flo first measures the flow she gets now by sticking the hose in a 50 gal drum and measuring how long it takes to fill. If it takes 25 minutes to fill the drum, what is Flo’s flow rate? (Remember: flow = volume / time) Flow = 50 gal / 25 min = 2 gal / min

25. Flo’s Flow Woes
1. What are TWO modifications of her watering equipment that Flo could make to double her flow?

26. Flo’s Flow Woes
1. What are TWO modifications of her watering equipment that Flo could make to double her flow? Flo could raise the tank (more PE so more KE) or use a larger hose (smaller resistance)

27. Flo’s Flow Woes
Flo’s Flower shop has a frequently frustrating flow problem. Flo runs grow lights all night. Unfortunately, Flo’s electrical flow (her electrical current) isn’t enough for her gloomy gladiolas.
2. Flo first measures the flow she gets now by sticking a meter on her power line and measuring how long it takes to store up 50 coulombs of charge. If it takes 0.25 seconds, what is Flo’s current? (Remember: current = charge / time and is measured in amps.)

28. Flo’s Flow Woes
Flo’s Flower shop has a frequently frustrating flow problem. Flo runs grow lights all night. Unfortunately, Flo’s electrical flow (her electrical current) isn’t enough for her gloomy gladiolas.
2. Flo first measures the flow she gets now by sticking a meter on her power line and measuring how long it takes to store up 50 coulombs of charge. If it takes 0.25 seconds, what is Flo’s current? (Remember: current = charge / time and is measured in amps.) Current = 50 coulombs / 0.25 sec = 200 amps

29. Flo’s Flow Woes
2. What are TWO modifications of her electrical equipment that Flo could make to double her flow?

30. Flo’s Flow Woes
2. What are TWO modifications of her electrical equipment that Flo could make to double her flow? Flo could increase the voltage (more PE so more KE) or use larger wires (smaller resistance)

31. Labette: Resistor Table
Use slide to practice resistor color code

32. Labette: Resistor Table
Check student answers before proceeding

33. Ohm’s Law Labette: Data
ALLOW students to copy data if needed. (Hand out hard copies if needed)

34. Ohm’s Law Post-Labette
I = V / R
As V increases, I increases
As R increases, I decreases
R = 330
R = 150
R = ???
Data plots will be VERY straight. Calculate slopes from END of LINES
Results agree with Ohm’ Law: V up I up, R up I down
Mystery resistor must be ??? than others
Calculate SLOPE of mystery resistor line … next slide

35. Ohm’s Law Post-Labette
Calculate the value of the mystery resistor using the formula:
R = 1000 / Slope
Example: 50
1000 / 50 = 20
Calculate value of mystery resistor from slope & compare to measured value. Agreement should be VERY good!
388

36. (Game Board & Pieces Archive)

37. WATER
ELEC’Y
ABBR
UNIT
DEWG Q I V R
Game Board – print on white

38. Charge Volume Coulomb Current Flow Ampere “Amp” Voltage Pressure Volt
Number of electrons
Volume
Amount of water
Coulomb
Current
Number of electrons per second
Flow
Amount of water per second
Ampere
“Amp”
Voltage
Force pushing electrons
Pressure
Force pushing water
Volt
RESIST-ANCE
Ohm
Pieces – print on yellow