Created for B-W Physics

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ELECTROSTATICSatB-W

• Created for B-W Physics
• by
• Dick Heckathorn
• 2 April 2K 8

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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

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Table of Contents

• 4 Investigating Charge
• 8 Building an Electroscope
• 9 Electrostatic Series
• 12 Inv. Separating Charges on Two Spheres
• 22 Charging by Conduction
• 24 Charging by Induction
• 26 Ripping of Charges
• 27 Burning off Charges
• 28 Concept Dev 32.2
• 32 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
• 62 Lyden Jar
• 64 Safe Place Outside

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1-1 Investigating Charge

• Need 2 4-inch (or so) pieces of
• Scotch magic tape with tab
• 1. Label one piece A and the other B.
• 2. Place each on the table.
• 3. Holding the tab, pull both off the table.
• 4. Bring them near each other.
• 5. What do you observe?
• 6. Record what you found.

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1-2 Investigating Charge

• 1. Label one piece C and the other D
• 2. Place tape C on the table. Then place tape D
  on top of it
• 3. Pull both off the table (together).
• 4. Bring them near each other.
• 5. What do you observe?
• 6. Compare C and D to A and B.
• 7. Record what you found.

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1-3 Investigating Charge

• 1. Place pieces of paper on the table.
• 2. Bring the charged pieces of tape near the
  paper.
• 3. What is the charge of the paper?
• 4. What is the charge of the tape?
• 5. Record what you found.

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1-4 Investigating Charge

• 1. How can we find out what the actual charge is
  on the pieces of tape?
• 2. Need some additional information
• 3. Where can you get it?
• 4. From a text or internet.
• 5. Record the charge on tape A, B, C, D

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2. Building an Electroscope 1E1 p 25 1F1 p 19

• a. Build an electroscope using a
• foam cup, straw, scotch tape
• b. Hang a piece of known charged tape on it.
• c. Bring and - charged tape near the
  hanging charged tape.
• d. Write down what you found.

Skip Electrostatic Series
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3-1 Electrostatic Series 1A3F p 17
How do we know which objects gains and which
objects lose electrons?

• 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)
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3-1 Electrostatic Series 1A3F p 17
Materials tend to receive electrons and become
NEGATIVELY CHARGED
Materials tend to lose electrons and become
POSITIVELY CHARGED
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3-2 Electrostatic Series

• Materials tend to
• receive electrons
• and become
• NEGATIVELY
• CHARGED
• Materials tend to
• 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
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4-1 Charge Separation Inv. p 27
Place two spheres so that they are touching.

• Rub white rod with wool

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4-2 Charge Separation
Bring white charged rod near one of the spheres.
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4-3 Charge Separation
Separate the two spheres.
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4-4 Charge Separation
Remove white rod
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4-5 Charge Separation
Bring small sphere near white rod.
Move small sphere along the white rod until it
repels
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4-6 Charge Separation
Remove white rod using care not to touch sphere.
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4-7 Charge Separation
Bring small sphere near each large sphere.
What happened?
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4-8 Charge Separation
Conclusion
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4-9 Charge Separation
Explanation
Brought white charged strip near one of spheres.
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4-10 Charge Separation
Spheres were separated.
White rod was removed.
Spheres were charged
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5-1 Charging by Contact (Conduction)1E2 p 29
1E3F p 33

• use wool, white rod, sphere on string.
• 1. rub white rod with wool
• 2. holding end of string, touch sphere to white
  rod
• 3. What happened to the sphere?
• 4. Try to make sphere jump and stay away from the
  white rod.
• 5. Check charge on white rod and sphere with your
  electroscope.

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5-2 Charging by Contact
Touch sphere to white rod.
Remove white rod
Charge of sphere same as rod
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6-1 Charging by Induction

• 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.

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6-2 Charging by Induction
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
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7. Ripping of Charges

• (scotch magnetic tape)
• 1. Place tape on chair seat.
• 2. Pull tape from the chair seat.
• 3. Check charge using the
• electroscope.
• 4. Can you find a surface that will give the
  ripped off tape a positive charge?

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8. Burning Off Charges

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

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9. Concept Development 32.2

Homework Get Worksheet
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Electrophorus - 1E4 p 39
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.
Check if there is a charge on plate by touching
plate to cheek.
Touching only the cup, place apparatus on foam.
No Charge on Plate
Setting Plate on Foam
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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
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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
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10. Demonstration

• Metal Rod
• and
• plastic coat hanger

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11. Demonstration

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

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12. Demonstration

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

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13. Demonstration

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

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14. Investigation

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

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

• How is it constructed?

See page 527 of text
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Van de Graaff Generator

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

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Van de Graaff Generator

• Spark jumps in dry air when

Spark jumps _____ cm.
Electric Potential Difference is?
V _____ volts
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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
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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
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Van de Graaff Demo

• Graphite Sphere

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Van de Graaff Demo

• Franklin Alert

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Van de Graaff Demo

• Glowing Ne2

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Van de Graaff Demo

• Fluorescent tube

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Van de Graaff Demo

• Charge a Person

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Van de Graaff Demo

• Christmas Tinsel

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Van de Graaff Demo

• Precipitator

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Van de Graaff Demo

• Propane Lighter Flame

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Van de Graaff Demo

• Aluminum Pie Pans

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Van de Graaff Demo

• Spinning Aluminum Strip

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Kelvin Water Drop Generator
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Electrophorus - 1E4 p 39
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.
Check if there is a charge on plate by touching
plate to cheek.
Touching only the cup, place apparatus on foam.
No Charge on Plate
Setting Plate on Foam
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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
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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
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Student Investigation 1G1, 1G2 p 41, 43

• Construct Lyden Jar

Materials 35 mm film canister with lid
paper clip aluminum foil water
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Construction Lyden Jar

• a. Cover outside film canister within 1 cm of top
  with aluminum foil
• b. Fill canister within 1 cm of top with water
• c. Place lid on canister
• d. Unbend paper clip, with small bend at one end.
• e. Insert pointed of clip into lid until the
  pointed end touches the bottom of the canister

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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.

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Demonstration

• Dissectible Lyden Jar

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Demonstration

• Ice Pail

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Discussion

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

Automobile?
Why?
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Demonstration

• Foam Can with plastic peanuts.
• Metal can with plastic peanuts
• Using VdG.

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Discussion

• How safe is an airplane?

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Handout

• Lighting Bolt Shatters Safety Rule

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Discussion

• Why do some homes and barns have lightning rods?
• Video Lightning

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

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Video

• Static Electricity at Gas Pump

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Video

• Lightning

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Thats all folks!