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  2. 2. The EarthMagnetic PolesNorth and SouthGeographic PolesNorth and SouthEarth is a giant magnet.
  3. 3. Magnetic Declination
  4. 4. InclinometerAn example of an inclinometer showing theEarth’s magnetic inclination
  5. 5. Compass PointsThe direction of compass points in UnitedStates
  7. 7. Natural MagnetMaterial is Magnetite or IronOxide (Fe2 03)
  8. 8. MagnetsA very strong magnet can be made witha coil of wire and the flow of an electriccurrent.
  9. 9. AlnicoAn extremely strong Alnico permanentmagnet with keeper
  10. 10. Theory of MagnetismMolecular and Electron Theories
  11. 11. Creating Magnets The pictureshows that ascrewdriver doesnot pick up paperclips.Methods used to create a magnet
  12. 12. Creating MagnetsStroking using a permanent magnet However, afterstroking thescrewdriver with amagnet, the bladeitself becomesmagnetic andattracts the paperclips.
  13. 13. Flux Magnetic lines offorce Strongest at thepoles
  14. 14. Removing MagnetismHeat is one way to removemagnetism.
  15. 15. Laws of MagnetsPoles attract or repel
  16. 16. Like Poles Repel
  17. 17. Laws of magnets shownby flux linesUnlike poles attract Like poles repel
  18. 18. Stray Lines of ForceControlling stray lines usinga keeper
  19. 19. Magnetic Lines of Force Notice how thematerials are affected Soft iron is a materialthat distorts fluxMagnetism will pass through any material
  20. 20. Electromagnetism
  21. 21. ElectromagnetsA 30-foot diameter electromagnetused in research for a superconductorA large electromagnetused to lift scrap metal
  22. 22. ElectromagnetsThe source of electromagnetism is electricity(current) flowing through a coil of wire.
  23. 23. ElectromagnetsA coil of wire can be made into a magnet by passing anelectric current through it.Without electricity,there is nomagnetic forceElectric current applied to a coilcreates a magnetic field
  24. 24. Electromagnetic Strength Increase the number of coils. Increase the electric current flowingthroughthe coil. Add an iron core in the center of the coil.How can an electromagnet be madestronger?
  25. 25. Electromagnetic Strength
  26. 26. The left hand rule todetermine North PoleNORTH POLE SOUTH POLE
  27. 27. Making a MagnetAn example of a very strong magnet
  28. 28. The magnet is strongenough to lift this 50pound engine cylinderhead.The coil of wire has beenattached to a 12 volt DCpower source making anextremely strong magnet.Making a Magnet
  29. 29. SaturationSaturation KneeY- AxisIncreasingMagneticForceYX- Axis Increasing ElectricCurrentXSaturation of a magnetic field occurs when an increase ofelectric current flow does not increase the strength of themagnetic field as shown by the graph. The knee of thecurve is the point that saturation occurs.
  30. 30. MAGNETIC COIL LOSSES Copper losses - resistance of coppercoils. Hysteresis - magnetic flux inducing acurrent in the core. Eddy currents - magnetic polarity of theiron core is rapidly changed by an ACcurrent causing friction and heatbetween the molecules
  32. 32. Electromagnetic Devices
  33. 33. Electromagnetic Devices
  34. 34. MAGNETIC TERMS Flux - Invisible lines of force. Poles - North and South where force isstrongest. Permeability – The ability of a material toconduct lines of force. Residual Magnetism – The ability of amaterial to hold its magnetism for a longtime.
  35. 35. MAGNETIC TERMS Ferromagnetic Material – A material easy tomagnetize. (i.e., Iron Steel, Cobalt, Perm-alloy,and Alnico) Paramagnetic Material- A material that can beslightly magnetized. Diamagnetic Material – A material that is verydifficult to magnetize. Magnetic Laws – Simply stated: Like polesrepel and unlike poles attract.
  36. 36. Review What are the poles of a magnet? Name the magnetic lines of force. List five types of magnets and their twofamilies. List the laws of magnets. Explain two methods for making a magnet.
  37. 37. Review Explain two theories of magnetism. Name five different types of devices that areassociated with electromagnetism? List three magnetic and three nonmagneticmaterials. What will remove magnetic lines of force?