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ELECTROSTATICS at B-W Chapter 32 of Text Book

ELECTROSTATICS at B-W Chapter 32 of Text Book. Created for B-W Physics by Dick Heckathorn 8 January 2K + 10. Table of Contents. A Investigating Charge B. Investigating Charge C. Investigating Charge D. What is the sign of the charge on the tapes? E. Building an Electroscope

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ELECTROSTATICS at B-W Chapter 32 of Text Book

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  1. ELECTROSTATICSatB-WChapter 32 of Text Book Created for B-W Physics by Dick Heckathorn 8 January 2K + 10

  2. Table of Contents • A Investigating Charge • B. Investigating Charge • C. Investigating Charge • D. What is the sign of the charge on the tapes? • E. Building an Electroscope • F. Electrostatic Series 1A3F p 31 • G. Induced Charge Separation • H. Charging by Contact (Conduction) • I. Demo: Charging by Induction • J. Demo: Ripping off Charges • K. Demo: Burning Off Charges • L. Concept Development 32.2 • M. Electrophorus

  3. Table of Contents • N. Demo: Electrostatic Attraction • O. Demo: Electrostatic Attraction • P. Demo: Electrostatic Attraction • Q. Demo: Petri Dishes • R. Electrical Units • S. Van de Graaff Generator • T. Demo: Graphite Sphere • U. Demo: Franklin Alert • V. Demo: Glowing Ne2 • W. Demo: Fluorescent tube • X. Demo: Charge a Person • Y. Demo: Christmas Tinsel • Z. Demo: Precipitator

  4. Table of Contents • AA. Demo: Propane Lighter Flame • AB. Demo: Aluminum Pie Pans • AC. Kelvin Water Drop Generator • AD. Construct Lyden Jar • AE. Demo: Dissectible Lyden Jar • AF. Demo: Ice Pail • AG. Demo: Plastic Peanuts in: • AH. How safe is an automobile? airplane? • AI. Why do some homes and barns have lightning rods? • AJ. Demo: Cloud Discharge • AK. Static Electricity at Gas Pump

  5. A. Investigating Charge • Need 2 4-inch (or so) pieces of • Scotch magic tape with tab • 1. Tear off 4 pieces of 5-inch strips of masking tape, fold a ½ inch piece over one end and stick it to the top of a table. • 2. Label one piece ‘A’ and the other ‘B’. • 3. Place each on the table.

  6. A. Investigating Charge • Need 2 4-inch (or so) pieces of • Scotch magic tape with tab • 4. Holding the tab, pull both off the table. • 5. Bring them near each other. • What do you observe? • 7. Repeat a few times. • 8. What do you find when you bring one of your pieces of tape near someone else’s piece of tape?

  7. B. Investigating Charge • Label a third piece of tape ‘C’ and a fourth ‘D’ • Place tape C on the table. Then place tape D on top of Tape C • Pull both pieces of tape off the table together. • 4. Separate the pieces of tape.

  8. B. Investigating Charge • Bring them near each other. • What do you observe? • 7. Compare tape ‘C’ and ‘D’ to tape ‘A’ and ‘B’. • 8. Record your findings.

  9. C. Investigating Charge • Place pieces of paper on the table. • Bring tape ‘C’ and tape ‘D’ near the pieces of paper. • Record what happened. • 4. What do you think the sign of the charge on the pieces of paper?

  10. D. What is the Sign of the Charge on the Pieces of Tape? • glass tubing, pieceof silk • 1. How can we find out what the actual charge is on the pieces of tape? • 2. Check the textbook or the internet to find out how the sign of a charge was defined by Ben Franklin.

  11. D. What is the Sign of the Charge on the Pieces of Tape? • glass tubing, piece of silk • 3. Use the information to find the charge on each of the pieces of tape. • 4. Record the charge on tape: • ’A’ __________ ‘B’ __________ • ‘C’ __________ ‘D’ __________

  12. E. Building an Electroscope 1E1 p 39 1F1 p 33 • foam cup, straw, scotch tape • 1. Construct an electroscope shown in the picture. • 2. Hang a piece of negative tape to it. • 3. Bring pieces of charged tape ‘C’ and ‘D’ near the hanging charged tape. • 4. Record what you observed. Skip Electrostatic Series

  13. F. Electrostatic Series 1A3F p 17 clear rod glass white rod (PVC Teflon Silk Rabbits fur cling wrap wool • 1. Set up the electroscope with a ‘-‘ piece of tape on it. • 2. Rub the clear rod, glass, silk, white rod, and Teflon with the rest of the items one at a time. Identify the sign of the charge on each using the electroscope.

  14. F. Electrostatic Series 1A3F p 17 • Silk Wool Cling Rabbit • Wrap fur • clear rod ___ ___ ___ ___ • glass rod ___ ___ ___ ___ • white rod ___ ___ ___ ___ • Teflon ___ ___ ___ ___

  15. F. Electrostatic Series 1A3F p 17 • Rank order the items from: • Materials tend to receive electrons and become NEGATIVELY CHARGED • Materials tend to lose electrons and become POSITIVELY CHARGED

  16. F. 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

  17. G-1. Induced Charge Separation Inv. p 41 • 1. Rub white rod with wool 2. Place two spheres so that they are touching.

  18. G-2. Induced Charge Separation 2. Bring rod near left sphere.

  19. G-3. Charge Separation 3. With the charged rod still in position, separate the two spheres and place them upright on the table

  20. G-4. Charge Separation 4. Remove the charged rod.

  21. G-5. Charge Separation 5. With the plastic rod still charged, touch the small sphere to the charged rod until it acquires the same charge as the rod.

  22. G-6. Charge Separation Remove white rod using care not to touch the sphere.

  23. G-7. Charge Separation Bring small sphere near each large sphere. What happened?

  24. G-8. Charge Separation Conclusion

  25. G-9. Charge Separation Explanation Brought white charged strip near one of spheres.

  26. G-10. Charge Separation Spheres were separated. White rod was removed. Spheres were charged:

  27. H. Charging by Contact 1. Rub the white rod with wool. 2. Touch sphere to white rod

  28. H. Charging by Contact • What happened to the sphere? • Continue rubbing the sphere along the rod until the sphere is constantly repelled by the white rod may be necessary. • Why? Charge of sphere same as rod

  29. I. Charging by Induction • Induction • (wool, white rod, sphere on string) • 1. Rub white rod with wool • 2. With sphere near the white rod, touch sphere with finger making sure the sphere does not touch the white rod. • 3. Check charge using the electroscope. • Rod ________ • Sphere _________

  30. I. 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

  31. J. Ripping off Charges • (scotch magic tape, electroscope) • 1. Place tape on various objects. • 2. Pull tape from the object. • 3. Check charge using the electroscope. • 4. Record any object that the tape tests positive.

  32. K. Burning Off Charges • (charged electroscope, match) • 1. Hang 2 negative charged pieces of tape on opposite sides of the electroscope horizontal arm. • 2. Bring burning match near the charged pieces of tape. • 3. Record what happens to the pieces of tape. Explain what happened.

  33. L. Concept Development 32.2 Hand out worksheet as homework Due Beginning of Class on __________

  34. M. Electrophorus - 1E4 p 39 aluminum plate, scotch tape, foam cup, piece of foam, wool Check charge on foam. Remove plate from foam. Rub foam with wool. 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

  35. 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

  36. 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

  37. N. Demo: Electrostatic Attraction • Metal Rod, Teflon rod, • plastic coat hanger Describe and explain what happened.

  38. O. Demo: Electrostatic Attraction • Wood Board • with • Teflon, Clear Rod and fur Describe and explain what happened.

  39. P. Demo: Electrostatic Attraction • Pop Cans • with • Teflon, Clear Rod and Fur Describe and explain what happened.

  40. R. Electrical Units

  41. Electrical Units Electric Potential

  42. Electrical Units Current

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

  44. Electrical Units What is an kilowatt-hour?

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

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

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

  48. 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

  49. 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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