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ELECTROSTATICS at B-W

ELECTROSTATICS at B-W. Created for B-W Physics by Dick Heckathorn 2 April 2K + 8. 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

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ELECTROSTATICS at B-W

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  1. ELECTROSTATICSatB-W Created for B-W Physics by Dick Heckathorn 2 April 2K + 8

  2. 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 • 65 Peanuts in Foam, Metal Can • 69 Lightning Rods

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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

  8. 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)

  9. 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

  10. 3-2 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 to • lose electrons • and become • POSITIVELY • CHARGED

  11. 4-1 Charge Separation Inv. p 27 Place two spheres so that they are touching. • Rub white rod with wool

  12. 4-2 Charge Separation Bring white charged rod near one of the spheres.

  13. 4-3 Charge Separation Separate the two spheres.

  14. 4-4 Charge Separation Remove white rod

  15. 4-5 Charge Separation Bring small sphere near white rod. Move small sphere along the white rod until it repels

  16. 4-6 Charge Separation Remove white rod using care not to touch sphere.

  17. 4-7 Charge Separation Bring small sphere near each large sphere. What happened?

  18. 4-8 Charge Separation Conclusion

  19. 4-9 Charge Separation Explanation Brought white charged strip near one of spheres.

  20. 4-10 Charge Separation Spheres were separated. White rod was removed. Spheres were charged:

  21. 5-2 Charging by Contact Touch sphere to white rod. Remove white rod Charge of sphere same as rod

  22. 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.

  23. 6-2 Charging by Induction 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. 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?

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

  26. 9. Concept Development 32.2 Homework Get Worksheet

  27. Electrophorus - 1E4 p 39 aluminum plate, scotch tape, foam cup, piece of foam, wool Remove plate from foam. 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. • Tape cup to aluminum plate. No Charge on Plate Setting Plate on Foam

  28. 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

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

  30. 10. Demonstration • Metal Rod • and • plastic coat hanger

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

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

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

  34. Electrical Units

  35. Electrical Units Electric Potential

  36. Electrical Units Electric Potential Investigate various batteries using a Christmas tree bulb and connecting wire. Investigate how batteries are constructed

  37. Electrical Units Current

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

  39. Electrical Units What is an kilowatt-hour?

  40. Van de Graaff Generator • How is it constructed? See page 527 of text

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

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

  43. 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

  44. 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

  45. Van de Graaff Demo • Graphite Sphere

  46. Van de Graaff Demo • Franklin Alert

  47. Van de Graaff Demo • Glowing Ne2

  48. Van de Graaff Demo • Fluorescent tube

  49. Van de Graaff Demo • Charge a Person

  50. Van de Graaff Demo • Christmas Tinsel

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