Magnetism

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  • A natural magnet from the Earth known as a loadstone is attracting a paper clip
  • An type of magnet.
  • Other example material include: METALS, WOOD, PLASTIC, CERAMICS, RUBBER, GLASS, COMPOSIT FIBERS, AND ALL COMPOUNDS
  • An example of a very strong magnet made with a coil of wire and the flow of an electric current.
  • Magnetism

    1. 1. MAGNETISMMAGNETISM
    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
    6. 6. Types of MagnetsLOADSTONEBARUCOILALNICO
    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
    31. 31. ELECTROMAGNETIC DEVICES
    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?

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