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Inside a Magnet

Inside a Magnet. The Atom. All magnets contain atoms, which are the smallest particles of an element that retain all the properties of the element. Atoms contain protons, neutrons and electrons. The Nucleus. Found at the center of an atom Contains the proton (positively charged)

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Inside a Magnet

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  1. Inside a Magnet

  2. The Atom All magnets contain atoms, which are the smallest particles of an element that retain all the properties of the element. Atoms contain protons, neutrons and electrons

  3. The Nucleus Found at the center of an atom Contains the proton (positively charged) and the neutron (neutrally charged) The rest of the atom is mainly empty space

  4. The Electron Negatively charged Found moving randomly throughout the empty space of an atom Electrons spin, which produce a magnetic field Atoms with strong magnetic properties have electrons that are not paired, so the magnetic fields of the electrons do not cancel.

  5. How a magnetic field is produced in an atom Electrons Spin A spinning electron produces a magnetic field that makes the electron behave like a tiny magnet.

  6. Magnets and Electrons Most electrons are paired Paired electrons spin in opposite directions – this makes the magnetic fields of the electrons cancel = weak magnetic properties

  7. Magnetic Domains Materials contain many atoms – for most materials the magnetic fields of their atoms cancel each other out since they point in many directions. For some materials, the magnetic fields of groups of atoms line up creating magnetic domains – each with a north pole and a south pole When the magnetic domains inside a material line up in the same direction the material is considered a magnet.

  8. When all or most magnetic domains inside a material line up in the same general direction the material is considered a magnet. When the magnetic domains inside the material don’t line up (cancel each other), the material is not a magnet Magnetic Domains

  9. Magnetic Domains In Other Words… Electrons spin creating magnetic fields  when groups of atoms have their magnetic fields aligned they create magnetic domains  when magnetic domains of a material are lined up in the same direction the material is a magnet!

  10. Magnetic Materials Materials that show strong magnetic properties are called ferromagnetic Ferro comes from the Latin word ferrum which means iron (the symbol for iron on the periodic table is Fe)

  11. Elements: Iron (Fe), Nickel (Ni), Cobalt (Co) and Gadolinium (Gd) or the rare Samarium (Sm) and Neodymium (Nd) Alloys (a combo of several metals): alnico (aluminum, nickel and cobalt); platinum (Pt) and cobalt; cobalt and neodymium Commonly used in magnets today: Ferrite

  12. Making Magnets Two ways to make a magnet: Place a ferromagnetic material (that is not already magnetized) in a strong magnetic field Rub a magnet’s pole over the material This causes the magnetic domains of the ferromagnetic material to become aligned

  13. Two types of magnets: Temporary: gains and loses magnetism easily Permanent: hard to magnetize and keeps being magnetized for a long time

  14. Destroying Magnets Two ways to destroy a magnet: Hit the magnet with a large force Heat the magnet to a certain temperature (actual temperature depends on the material) In both cases the magnetic domains become unaligned and the material loses its magnetic properties

  15. Breaking Magnets Most of the magnetic domains of a magnet point in the same direction.When a magnet is broken the magnetic domains still point in the same direction.

  16. Earth’s Magnetic Poles Based on the fact that compass needles point north, where is the magnetic north pole? Is it with the polar bears in the Artic or with the penguins in the Antarctic? It’s with the penguins! http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magearth.html

  17. Earth’s Magnetic Field Dynamo Effect Earth’s Core Convection Currents Electric Currents Magnetic Field

  18. The Moving Poles http://gsc.nrcan.gc.ca/geomag/nmp/northpole_e.php http://science.nasa.gov/headlines/y2003/29dec_magneticfield.htm

  19. Magnetic Reversals Evidence: Magnetic stripes, core samples, ships logs, computer models Causes Last flip 800,000 years ago Time for flip

  20. Magnetic Reversals Computer models http://science.nasa.gov/headlines/y2003/29dec_magneticfield.htm

  21. Animals Turtles, homing pigeons, lobsters, etc Navigation: direction + location How would changing the Earth’s magnetic fields affect these animals?

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