1 Created for CVCA Physics By Dick Heckathorn 25 February 2K + 5 ELECTROSTATICS at CVCA

2 Table of Contents 4Investigating Charge4 8Building an Electroscope8 9Electrostatic Series9 1212Inv. Separating Charges on Two Spheres 2323Charging by Conduction 2525 Charging by Induction 2727Ripping of Charges 2828Burning off Charges 2929Concept Dev Demo Metal Rod Coat Hanger 3434Inv Charges in Petri Dish 3535Van de Graaff Generator 3636VDG How Dangerous is it? 4141Energy Units 4343Bulb lit using various size batteries 5050VDG Demonstrations 5656Electrophorus (Neg) 5959Electrophorus (Pos) 6262Lyden Jar 6464Safe Place Outside 6565Peanuts in Foam, Metal Can 6969Lightning Rods

3 1. Investigating Charge Need 2 4-inch (or so) pieces of Scotch magic tape with tab a.place each on table. A B b.pull both off table. c.bring them near each other. d.What do you observe? e.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. d.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 furrubber 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 paper silk cat’s fur wool nylon glass rabbit’s 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

Investigation Place two spheres so that they are touching. Rub white rod with wool

Investigation Bring white charged rod near one of spheres.

Investigation Separate the two spheres.

Investigation Remove white rod

Investigation Bring small sphere near white rod. Touch small sphere to white rod until it repels

Investigation Remove white rod using care not to touch sphere.

Investigation Bring small sphere near each large sphere. What happens?

Investigation Explanation

Investigation Brought white charged strip near one of spheres. What’s happening?

Investigation white rod was removed. Spheres were separated. Spheres were charged:

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 Touch sphere to white rod.Remove white rod 9. Charging by Contact 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 Induction Explanation Touch with finger. Remove finger. Remove rod. Bring sphere near negative strip. Electrons move to opposite side. 9. Method of Charging 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 Investigate various batteries using a Christmas tree bulb and connecting wire. Investigate how batteries are constructed Electric Potential

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 Spark jumps in dry air when Van de Graaff Generator Spark jumps _____ cm. Electric Potential Difference is? V = _____ volts

42 = ____ watts _______ volts x 10 micro-amps Van de Graaff Generator How dangerous is a spark? Spark lasts for 10 micro-sec ____ watts x 10 micro-sec ________ Joules Taken from our generator and data sheet.

43 Van de Graaff Generator How dangerous is a spark? 350,000 volts 3.50 watts Spark lasts for 10 micro-sec 3.5 watts. 10 micro-sec 3.5 x Joules 350,000 volts, 10 micro-amps Taken from data sheet.

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 Touching only the cup, place apparatus on foam. 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 charge on plate by touching plate to cheek. Electrophorus - No Charge on Plate Setting Plate on Foam

56 Electrophorus - Place apparatus on foam. Touch bottom of aluminum plate with finger. Remove finger. Remove plate from foam. Check charge on plate. Check charge on foam. How does this happen? Touching Plate on Foam

57 Finger touches plate Place plate on negative foam Electrons leave plate ‘-’ repelled from bottom to top of plate Finger removed from plate Foam rubbed with wool Wool gives ‘-’ to foam Leaving ‘+’ behind Charges rearrange Electrophorus - Remove plate from foam

58 Check charge on plate. Check charge on foam. Electrophorus + Rub foam with wool. Tape cup to aluminum plate. aluminum plate, masking tape, foam cup, piece of foam, wool Place apparatus on foam. No Charge on Plate Remove plate from foam. Setting Plate on Foam

59 Electrophorus + Place apparatus on foam. Touch bottom plate with finger. Remove finger. Remove plate from foam. Check charge on plate. Check charge on foam. 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 1.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 That’s 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 paper silk cat’s fur wool nylon glass rabbit’s fur

74 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 paper silk cat’s fur wool nylon glass rabbit’s fur

75 Finger touches plate Place plate on negative foam Electrons leave plate ‘-’ repelled from bottom to top of plate Finger removed from plate Foam rubbed with wool Wool gives ‘-’ to foam Leaving ‘+’ behind Charges rearrange Electrophorus Remove plate from foam

76 Place plate on negative foam Electrophorus + Foam rubbed with woolWool takes ‘-’ from foam ‘-’ attracted to bottom of plate Leaving ‘+’ behind Finger touches plate Electrons added to plate Finger removed from plate Charges rearrange Remove plate from foam

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 If radius of dome is 1 meter Van de Graaff Generator Ours _______. Radius of our dome? _____

79 Van de Graaff Generator What is our potential difference? Spark length is ______? Electric Potential Difference is? _______ volts ______ volts/cm Taken from laser disk and using our generator.