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ELECTROSTATICS at CVCA

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

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ELECTROSTATICS at CVCA

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  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 • 64 Safe Place Outside • 65 Peanuts in Foam, Metal Can • 69 Lightning Rods

  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 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 Teflon Vinyl (PVC) Cling wrap rubber balloon silk wool Clear rod Rabbits fur glass • Materials tend to • receive electrons • and become • NEGATIVELY • CHARGED • Materials tend too • Lose electrons • And become • POSITIVELY • CHARGED

  10. 8-1 Investigation Place two spheres so that they are touching. • Rub white rod with wool

  11. 8-3 Investigation Bring white charged rod near one of spheres.

  12. 8-4 Investigation Separate the two spheres.

  13. 8-5 Investigation Remove white rod

  14. 8-6 Investigation Bring small sphere near white rod. Touch small sphere to white rod until it repels

  15. 8-7 Investigation Remove white rod using care not to touch sphere.

  16. 8-8 Investigation Bring small sphere near each large sphere. What happens?

  17. 8-9 Investigation Explanation

  18. 8-10 Investigation What’s happening? Brought white charged strip near one of spheres.

  19. 8-11 Investigation Spheres were charged: Spheres were separated. white rod was removed.

  20. 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.

  21. 9. Charging by Contact Touch sphere to white rod. Remove white rod Charge of sphere same as rod

  22. 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.

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

  24. 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?

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

  26. Concept Development 32.2 Homework

  27. Demonstration • Metal Rod • and • plastic coat hanger

  28. Demonstration • Wood Board • with • Teflon, Clear Rod and fur

  29. Demonstration • Pop Cans • with • Teflon, Clear Rod and Fur

  30. Demonstration • Pie pan, paper holes • with • Wool, fur or…

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

  32. Electrical Units

  33. Electrical Units Electric Potential

  34. Electrical Units Current

  35. Electrical Units What is a volt times an amp?

  36. Electrical Units What is an kilowatt-hour?

  37. Van de Graaff Generator • How is it constructed? Go to Classical Physics D-44

  38. Van de Graaff Generator • How dangerous is our • Van de Graff • generator?

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

  40. 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

  41. Van de Graaff Demo • Graphite Sphere

  42. Van de Graaff Demo • Franklin Alert

  43. Van de Graaff Demo • Fluorescent tube

  44. Van de Graaff Demo • Charge a Person

  45. Van de Graaff Demo • Christmas Tinsel

  46. Van de Graaff Demo • Precipitator

  47. Van de Graaff Demo • Aluminum Pie Pan

  48. Kelvin Water Drop Generator

  49. Electrophorus - aluminum plate, scotch tape, foam cup, piece of foam, wool Remove plate from foam. Rub foam with wool. Check charge on foam. Check charge on plate by touching plate to cheek. Touching only the cup, place apparatus on foam. • Tape cup to aluminum plate. No Charge on Plate Setting Plate on Foam

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

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