Magnets by ewghwehws



   Jiacheng Xu
    Tao Chen
     Chu Wu
       What we learn in class
• Recall that a magnet is a material or
  object that produces a magnetic field.
• Our Professor mentioned a little about
  magnets. Now, we will continue to learn
  more about Magnets
        What are Magnets
• Magnets are materials that
  produce a magnetic field of
  their own. Extreme
  examples of magnets are
  (1) "hard" or "permanent"
  magnets (like refrigerator
  magnets), which remember
  how they have been
  magnetized, and (2) "soft"
  or "impermanent" magnets
  (like the material of a
  refrigerator door)
         Two types of Magnets
• lodestone
- natural permanent magnet
- exert a force on objects without any outside
• electromagnets
- They are made by surrounding certain
  materials with a coil of wire.
- When an electric current is passed through the
  coil, these materials exert a magnetic force.
lodestone VS electromagnets

  How do Magnets work
The molecules in magnets are arranged so that the
electrons spin in the same direction. This
arrangement of atoms creates two poles in a
magnet, a North-seeking pole and a South-seeking

   The magnetic force in a magnet flows from the
   North pole to the South pole. This creates a
   magnetic field around a magnet.
      How do Magnets work
If you try to push the South poles or north poles
 together, they will repel each other.

If you try to push the south pole and north pole
together, they will attract each other.
Temperatures and Magnets
The maximum temperature       operate at, without
 that a magnet may be         becoming severely
 effectively used at          demagnetized. Shown
 depends greatly on the       here are approximate
 'permeance coefficient' -    maximum operating
 which is a function of the   temperatures for the
 magnetic circuit - the       various classes of magnet
 magnet is operating in.      material. At temperatures
 The higher the permeance     close to those listed here,
 coefficient (the more        special attention may be
 'closed' the circuit), the   needed in order to ensure
 higher temperature at        that the magnet will not
 which the magnet may         become demagnetized.
Temperatures and Magnets
     The use of Magnets

• Maglev trains
• Sort magnetic and non-magnetic materials
• Magnets are also used in compasses
Make your own Magnets
  What you need
• card stock or any other heavy

• magnetic tape

• markers or crayons
    Make your own Magnets
               What you do
• Cut a little piece of any shapes from the card
  stock and color it with markers or crayons.
• Place a small piece of magnetic tape onto the
  back of the magnet. Make sure to remove the
• Use the magnets to stick paper or sheets on
  your fridge or any other metal surface.
Thank you
     Jiacheng Xu
       Tao Chen
        Chu Wu

To top