Created for CVCA Physics

1
ELECTROSTATICSatCVCA

• Created for CVCA Physics
• By
• Dick Heckathorn
• 25 February 2K 5

2
Table of Contents

• 4 Investigating Charge
• 8 Building an Electroscope
• 9 Electrostatic Series
• 12 Inv. Separating Charges on Two Spheres
• 23 Charging by Conduction
• 25 Charging by Induction
• 27 Ripping of Charges
• 28 Burning off Charges
• 29 Concept Dev 32.2
• 30 Demo Metal Rod Coat Hanger
• 34 Inv Charges in Petri Dish
• 35 Van de Graaff Generator
• 36 VDG How Dangerous is it?
• 41 Energy Units
• 43 Bulb lit using various size batteries
• 50 VDG Demonstrations
• 56 Electrophorus (Neg)
• 59 Electrophorus (Pos)
• 62 Lyden Jar

3
1. Investigating Charge

• Need 2 4-inch (or so) pieces of
• Scotch magic tape with tab
• place each on table. A B
• pull both off table.
• c. bring them near each other.
• What do you observe?
• What else do you observe?

4
2. Investigating Charge

• a. Place tape C on the table. Then place tape D
  on top of it
• b. Pull both off table (together).
• c. Bring them near each other.
• What do you observe?
• e. Compare C and D to A and B

5
3. Investigating Charge

• a. Place pieces of paper on the table.
• b. Bring the charged pieces of tape near the
  paper.
• c. What is the charge of the paper?
• d. What is the charge of the tape?

6
3a. And The Charge Is.

• a. How can we find out what the actual charge is
  on the pieces of tape?
• b. Need some additional information
• c. Where can we get it?
• d. From the text.

7
4. Construction

• a. Build an electroscope using a foam cup,
  straw, scotch tape
• b. Place piece of charged tape on it.
• c. Learn how to use it.

Skip Electrostatic Series
8
5. Electrostatic Series

• a. Investigate rubbing one with the other and
  then determine the charge on each.

clear rod cling wrap glass Teflon
Rabbits fur rubber balloon silk wool white
rod (PVC)
9
6. Electrostatic Series

• Materials tend to
• receive electrons
• and become
• NEGATIVELY
• CHARGED
• Materials tend too
• Lose electrons
• And become
• POSITIVELY
• CHARGED

Teflon Vinyl (PVC) Cling wrap rubber
balloon silk wool Clear rod Rabbits fur glass
Teflon Vinyl (PVC) Saran wrap Polyester hard
rubber rubber balloon sealing wax Lucite wood pape
r silk cats fur wool nylon glass rabbits fur
10
7. Method of Charging

• a. Conduction
• use wool, white rod, sphere on string.
• b. place like charge on sphere after rubbing
  strip with wool.
• c. check charge with electroscope

11
8-1 Investigation

• Rub white rod with wool

Place two spheres so that they are touching.
12
8-3 Investigation
Bring white charged rod near one of spheres.
13
8-4 Investigation
Separate the two spheres.
14
8-5 Investigation
Remove white rod
15
8-6 Investigation
Bring small sphere near white rod.
Touch small sphere to white rod until it repels
16
8-7 Investigation
Remove white rod using care not to touch sphere.
17
8-8 Investigation
Bring small sphere near each large sphere.
What happens?
18
8-9 Investigation
Explanation
19
8-10 Investigation
Brought white charged strip near one of spheres.
Whats happening?
20
8-11 Investigation
Spheres were charged
white rod was removed.
Spheres were separated.
21
9. Method of Charging

• Conduction
• (wool, white rod, sphere on string)
• a. Rub white rod with wool
• b. Touch sphere to white rod until it repels.
• c. Check charge using the electroscope.

22
9. Charging by Contact
Touch sphere to white rod.
Remove white rod
Charge of sphere same as rod
23
9. Method of Charging

• Induction
• (wool, white rod, sphere on string)
• a. Rub white rod with wool
• b. With sphere near the white rod, touch sphere
  with finger making sure the sphere does not touch
  the white rod.
• c. Check charge using the electroscope.

24
9. Method of Charging
Remove finger.
Induction Explanation
Touch with finger.
Remove rod.
Bring sphere near negative strip.
Electrons move to opposite side.
Positive charges remain near rod.
Electrons escape from sphere
25
9. Method of Charging

• Ripping Off Charges
• (scotch magnetic tape)
• a. Place tape on chair seat.
• b. Pull tape from the chair seat.
• c. Check charge using the
• electroscope.
• d. Can you find a surface that will give the
  ripped off tape a positive charge?

26
9. Method of Charging

• Burning Charges
• (charged sphere on string, match)
• a. Bring burning match near charged sphere.
• b. Check charge using the electroscope.

27
Concept Development 32.2

Homework
28
Demonstration

• Metal Rod
• and
• plastic coat hanger

29
Demonstration

• Wood Board
• with
• Teflon, Clear Rod and fur

30
Demonstration

• Pop Cans
• with
• Teflon, Clear Rod and Fur

31
Demonstration

• Pie pan, paper holes
• with
• Wool, fur or

32
Investigation

• Petri dish, paper holes
• with
• Wax paper, wool, cling wrap and/or paper

33
Electrical Units
34
Electrical Units
Electric Potential
35
Electrical Units
Electric Potential
Investigate various batteries using a Christmas
tree bulb and connecting wire.
Investigate how batteries are constructed
36
Electrical Units
Current
37
Electrical Units
What is a volt times an amp?
38
Electrical Units
What is an kilowatt-hour?
39
Van de Graaff Generator

• How is it constructed?

Go to Classical Physics D-44
40
Van de Graaff Generator

• How dangerous is our
• Van de Graff
• generator?

41
Van de Graaff Generator

• Spark jumps in dry air when

Spark jumps _____ cm.
Electric Potential Difference is?
V _____ volts
42
Van de Graaff Generator
Taken from our generator and data sheet.

• How dangerous is a spark?

_______ volts x 10 micro-amps
____ watts
Spark lasts for 10 micro-sec
____ watts x 10 micro-sec
________ Joules
43
Van de Graaff Generator
Taken from data sheet.

• How dangerous is a spark?

350,000 volts
350,000 volts, 10 micro-amps
3.50 watts
Spark lasts for 10 micro-sec
3.5 watts . 10 micro-sec
3.5 x 10-5 Joules
44
Van de Graaff Demo

• Graphite Sphere

45
Van de Graaff Demo

• Franklin Alert

46
Van de Graaff Demo

• Glowing Ne2

47
Van de Graaff Demo

• Fluorescent tube

48
Van de Graaff Demo

• Charge a Person

49
Van de Graaff Demo

• Christmas Tinsel

50
Van de Graaff Demo

• Precipitator

51
Van de Graaff Demo

• Propane Lighter Flame

52
Van de Graaff Demo

• Aluminum Pie Pan

53
Van de Graaff Demo

• Spinning Aluminum Strip

54
Kelvin Water Drop Generator
55
Electrophorus -
aluminum plate, scotch tape, foam cup, piece of
foam, wool
Remove plate from foam.

• Tape cup to aluminum plate.

Rub foam with wool.
Check charge on foam.
Touching only the cup, place apparatus on foam.
Check charge on plate by touching plate to cheek.
No Charge on Plate
Setting Plate on Foam
56
Electrophorus -
Check charge on foam.
Place apparatus on foam.
Touch bottom of aluminum plate with finger.
Remove finger.
Remove plate from foam.
Check charge on plate.
How does this happen?
Touching Plate on Foam
57
Electrophorus -
Remove plate from foam
Finger touches plate
Place plate on negative foam
- repelled from bottom to top of plate
Foam rubbed with wool
Electrons leave plate
Finger removed from plate
Wool gives - to foam
Leaving behind
Charges rearrange
58
Electrophorus
Check charge on foam.
Rub foam with wool.

• Tape cup to aluminum plate.

aluminum plate, masking tape, foam cup, piece of
foam, wool
Remove plate from foam.
Check charge on plate.
Place apparatus on foam.
No Charge on Plate
Setting Plate on Foam
59
Electrophorus
Check charge on foam.
Place apparatus on foam.
Touch bottom plate with finger.
Remove finger.
Remove plate from foam.
Check charge on plate.
How does this happen?
Touching Plate on Foam
60
Student Investigation

• Construct Lyden Jar

Materials 35 mm film canister with lid
large paper clip aluminum foil water
61
Student Investigation

• a. Charge electrophorus
• b. While holding the film canister, touch it to
  paper clip
• c. Charge and touch to paper clip 8 to 10 more
  times
• d. Then touch foil and paper clip at the same
  time with finger and thumb of one hand.

62
Demonstration

• Dissectible Lyden Jar

63
Demonstration

• Ice Pail

64
Discussion

• Where is a safe place outside when an electrical
  storm is present?

Automobile?
Why?
65
Demonstration

• Foam Can with plastic peanuts.
• Metal can with plastic peanuts
• Using V.d.G.

66
Discussion

• How safe is an airplane?

67
Handout

• Lighting Bolt Shatters Safety Rule

68
Discussion

• Why do some homes and barns have lightning rods?

69

• Demo Use two aluminum pans connected to van de
  Graaff to demonstrate cloud
• - set pointed object in bottom of pan

70
Video

• Lightning

71
Video

• Static Electricity at Gas Pump

72
Thats all folks!
73
6. Electrostatic Series

• Materials tend to
• receive electrons and
• and become
• NEGATIVELY
• CHARGED
• Materials tend too
• Lose electrons
• And become
• POSITIVELY
• CHARGED

Teflon Vinyl (PVC) Saran wrap Polyester hard
rubber rubber balloon sealing wax Lucite wood pape
r silk cats fur wool nylon glass rabbits fur
74
6. Electrostatic Series
wood paper silk cats fur wool nylon glass ra
bbits fur

• Materials tend to
• receive electrons and
• and become
• NEGATIVELY
• CHARGED
• Materials tend too
• Lose electrons
• And become
• POSITIVELY
• CHARGED

Teflon Vinyl (PVC) Saran wrap Polyester hard
rubber rubber balloon sealing wax Lucite
75
Electrophorus
Remove plate from foam
Finger touches plate
Place plate on negative foam
- repelled from bottom to top of plate
Foam rubbed with wool
Electrons leave plate
Finger removed from plate
Wool gives - to foam
Leaving behind
Charges rearrange
76
Electrophorus
Place plate on negative foam
Foam rubbed with wool
Wool takes - from foam
- attracted to bottom of plate
Leaving behind
Finger touches plate
Electrons added to plate
Charges rearrange
Remove plate from foam
Finger removed from plate
77
Equipment

• ___ Box New Batteries 4
• ___ Box Old Batteries 4
• ___ Box Film Canisters 4
• ___ Box Pop Cans
• ___ Box Petri Dishes 4
• ___ Box E-1 Electrostatics 4
• ___ Box E-2 Electrostatics 4
• ___ Box E-3 Electrostatics 4
• ___ Box E-4 Electrostatics 4
• ___ Box E-4a Electrostatics 4
• ___ Box E-11 Electrostatics Lab 4
• ___ Van de Graff Generator 4
• ___ Van de Graff Generator Sphere 4
• ___ Video Lightning ???
• ___ Box E-5 Kelvin Water Drop 4
• ___ Box E-__ Foam Squares

78
Van de Graaff Generator
Ours _______.

• If radius of dome is 1 meter

Radius of our dome? _____
79
Van de Graaff Generator
Taken from laser disk and using our generator.

• What is our potential difference?

______ volts/cm
Spark length is ______?
Electric Potential Difference is?
_______ volts