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  1. Electromagnetism

  2. Bellringer • Have you ever heard of electromagnetism? If so, what is it? If not what do you think it is?

  3. Objective • Take a stroll down science history lane to investigate the discovery of one of my personal favorite areas of physics! • Aka learn what electromagnetism is.

  4. Andre-Marie Ampere • In 1826 Andre-Marie Ampere discovered his own law. • While experimenting with electrical current in his laboratory Monsieur Ampere made a ground breaking discovering that led to the combination of two phenomena that were previously thought to be separate.

  5. Ampere’s Law • His law stated that when current is moving through a wire a magnetic field is produced.

  6. Ampere’s Law • Before his discovery we thought that magnets were just these magical things that pointed north all the time. • After scientists knew that magnets were somehow related to electricity, but they just had no idea how or why. • So we started messing around!

  7. Michael Faraday • In 1831 both British scientist Michael Faraday, and American scientist Joseph Henry made a remarkable discovery about the interaction of wires and magnets. • Faraday published his findings first so he received all the credit for it.

  8. Michael Faraday Demos • Let’s go through Faraday’s original discovery and his further experiments thereafter • Original setup • Induced current • Amount of coils • Size of coils • Induced magnetic field • Magnetic field to current to magnetic field • Current to magnetic field to current

  9. Electromagnetic Induction • Electromagnetic Induction is the production of a voltage across a conductor when it is exposed to a varying magnetic field. • So moving magnets around a conductor produces electricity. • Electricity also produces a magnetic field.

  10. Faraday’s Law of Induction • Faraday’s Law of Induction is a basic law of electromagnetism predicting how a magnetic field will interact with an electric circuit to produce an electromotive force (EMF).

  11. Faraday’s Law of Induction • It is the fundamental principle of transformers, electric guitars, inductors, electrical motors, speakers, generators, the modern electrical power grid, solenoids, rail guns, electromagnets, levitating trains, launching rollercoasters, MRI machines, and particle accelerators.

  12. Railguns •

  13. Magnetic Field •

  14. Bellringer • How can you create an electrical current using a bar magnet?

  15. Objective • Investigate the shape of different magnetic fields.

  16. Magnetic Fields • When drawing magnetic field lines your arrows should go from North to South.

  17. Bellringer • Which way does a magnetic field point? • From north to south

  18. Objective • Finish investigating the majesty of magnetic fields.

  19. Missing Labs • Series-Parallel Circuits Lab: • Jon D • Jessica G • NaziaR • Caleb R • Cody W • NYSEG Engineer: • Caleb R • Meghann K • Running Some Wire Lab: • Matt O • Jon D • Caleb R

  20. Electric Current and Circuits Test • The class average is currently an 86.2 with two zeros still in it. • I can show you your test, but you cannot keep them yet.

  21. Mapping Magnet Fields Lab • Take a minute to read over the lab…it’s a good one! • Once you’re done reading meet me in the back!

  22. Bellringer - Collected • What did Michael Faraday discover and how is it important to modern society? DO WORK STOP

  23. Objectives • Observe and learn some of the causes, effects, and uses of electromagnetic induction and the electromagnetic force.

  24. Missing Labs • Series-Parallel Circuits Lab: • Jon D • Jessica G • NaziaR • Caleb R • Cody W • NYSEG Engineer: • Caleb R • Meghann K • Running Some Wire Lab: • Matt O • Jon D • Caleb R

  25. Recap • What is electromagnetic induction? • What is the electromagnetic force?

  26. Demos • As we go through these demos you will be taking notes about the trends and discoveries we make. • We’re going to have a single mod quiz on electromagnetism this Thursday (3/13). • Study your notes, and lab data.

  27. Dangers Liquid Nitrogen is about-320 Degrees Fahrenheit! • Some of these demos will involve high voltages and liquid nitrogen so any foolishness will not be tolerated. • If you listen to me you will not be electrocuted or frozen.

  28. Acknowledgments • Special thanks to Mark Stephens for supplying us with the variable high voltage power supply and the liquid nitrogen • Without him the demos would be boring

  29. Bellringer • Who was Andre Ampere and what did he discover? • He was a French physicist who discovered that moving charge particles produce a magnetic field. DO WORK STOP

  30. Objectives • Finish investigating the many demos and applications of electromagnetism • Go over the Mapping Magnets lab and review concepts for tomorrow’s quiz

  31. Missing Labs • Series-Parallel Circuits Lab: • Jon D • Caleb R • Cody W • NYSEG Engineer: • Caleb R • Meghann K • Running Some Wire Lab: • Matt O • Jon D • Caleb R

  32. Tomorrow’s E&M Quiz • 10ish multiple choice/fill in • 2 written response • No math…maybe

  33. Electromagnetic Force • Solenoid Demos • Jumping Ring • What makes the ring jump higher? Why? • Large Magnets • Electron beam deflection • Electric Motor • Electromagnets

  34. Electromagnets • Demo • Can you make one?

  35. Electromagnets • How strong can you make an electromagnet? •

  36. Electromagnetic Motors • Demos • Draw this diagram • How fast can it spin?

  37. Speakers: Why are they so heavy? • Speakers use a coil of wire and a magnet to vibrate the cone and produce sound

  38. Electron Gun Demo • What will happen to the electron beam when a magnet is placed near it? • What if we use a really big magnet?

  39. Mapping Magnets Lab • Who needs more time? • How much time do you need?

  40. Magnetic Fields • Which is the best way to map a magnetic field with a compass, or with iron filings? Why? • Both have their benefits. Compass method will give you the direction of the field, but iron filings will give you more magnetic field lines.

  41. Shape of a Magnetic Field • Cow Magnet Demo

  42. Magnetic Field Lines • Magnetic field lines are similar to electric field lines • The field lines show which way a ferromagnetic material will align itself.

  43. Ferromagnetic • Ferromagnetic materials have a large susceptibility to an external magnetic field. • They exhibit a strong attraction to magnetic fields and are able to retain their magnetic properties after the external field has been removed. Iron is a good example.

  44. Earth’s Magnetic Field • Is the North Pole in the north? • Nope. If it was then the north pole of a compass would point to the south because magnetic field lines go north to south.

  45. Earth’s Poles

  46. Bellringer • Which direction do magnetic field lines go?

  47. Objectives • Finish up electromagnetism • Take electromagnetism quiz

  48. Magnets • Every magnet has a north and a south pole. • Even if you break a magnet in half, the two new pieces will each have a north and a south pole. • No one has ever broken a magnet or even a piece off of a magnet so that it only has a single pole.

  49. Earth’s Magnetic Field (Shield) • • What would happen if we didn’t have this shield? • What is our shield called? • Why is the shape of the field distorted? • What is the size of the field? • What happens to Earth when some radiation gets through the first layer of defense?