1 / 22

Lecture 23

Lecture 23. Dead Cats & The Basics of Electricity Bolemon Parts of Chapters 17-20. Probable First Observation of Electricity. Idiot?. If lightening had actually traveled down the kite string, old Ben Franklin would have been toast!. Don’t Mess With Mother Nature St. Elmo’s Fire.

irag
Télécharger la présentation

Lecture 23

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Lecture 23 Dead Cats & The Basics of Electricity Bolemon Parts of Chapters 17-20

  2. Probable First Observation of Electricity

  3. Idiot? If lightening had actually traveled down the kite string, old Ben Franklin would have been toast!

  4. Don’t Mess With Mother NatureSt. Elmo’s Fire Top of Mast

  5. History • 600 BC • Thales of Miletos rubs amber (elektron in Greek) and observed some strange effects. • Important questions: • Why was he doing this? • Didn’t he have a job?? • What happened to the skinned cat?

  6. Amber Million years ago large stands of forests in some parts of the world began to seep globs of sticky resin! This aromatic resin oozed down the sides of trees, as well as filling internal fissures, trapping debris, such as seeds, leaves, feathers and insects. As geologic time progressed the forests were buried and the resin hardened into a soft, warm, golden gem, known as amber. Amber is the fossilized resin of ancient trees which forms through a natural polymerization of the original organic compounds. Most of the world's amber is in the range of 30-90 million years old.

  7. Let's reproduce some of the early experiments

  8. WARNING! These experiments do not always work! Humidity can hurt so do not exhale for the next 30 minutes!

  9. Scotch tape • Required – 1 roll of tape • 1 volunteer • Observers

  10. Demo Objects • Dead Cat – Skinned … keep the skin • Rubber Rods • Glass Rods • Silk Cloth • Wood • Aluminum • Metal 2 x 4 on a stand

  11. 0 / 34 Rub 2 rubber rods with the skin of a dead cat • They will attract each other • They will repel each other • They will not interact with each other • It depends on when you killed the cat. Cross-Tab Label

  12. 0 / 34 How does the Force of interaction depend on the distance? • It increases as the distance gets smaller between them. • It is independent of the distance. • It increases as the distance gets bigger. Cross-Tab Label

  13. 0 / 34 Rub 2 glass rods with silk • The rods will attract • The rods will repel • The rods won’t do anything. Cross-Tab Label

  14. 0 / 34 Rubber rods with silk • Attract • Repel • Nothing • They will explode Cross-Tab Label

  15. 0 / 34 Rubber/Cat + glass/silk • Attract • Repel • Ignore each other Cross-Tab Label

  16. 0 / 34 Rubber and Cat’s Fur • Attract • Repel • No interaction Cross-Tab Label

  17. Some of the observations-RODS

  18. PLUS • The Glass attracted the silk • The Rubber attracted the dead cat

  19. Two Kinds of Interaction • Attraction • Repulsion

  20. Some conclusions (corrected) • When two things are rubbed together, something happens. • We call what happens .. charging. • It seems that there are two kinds of charge • The rubber charge is called NEGATIVE • The cat charge is called POSITIVE • Like Charges Repel • Un-Like charges Attract

  21. 0 / 34 Based on our observations today, what charge winds up on the glass rod when rubbed by silk? • POSITIVE • NEGATIVE • Can’t Tell Cross-Tab Label

  22. Two by Four

More Related