Magnetism technical

• Magnetism


  Caused by electrical charges in motion.
• Magnets have “poles”

  North seeking pole

  South seeking pole

  Always occur in pairs.
• Just like electrical charges

  Opposite poles attract, like repel.
• magnetic pole attraction cs electrical force attraction

  Both attract and repel w/o contact which means the are field forces.

  the strength of interaction depends on how close together they are ie: the distance
• Magnetic pole attraction vs electric force attraction

  The difference is that electric charges can be isolated & magnetic poles cannot (electrons can exist alone w/o protons, but a North Pole or South Pole cannot).
• Permanent magnets

  • Metals can become magnets by coming in contact with a permanent magnet.

  • Process can be reversed by heating/cooling or hammering the material.

  •hammering shifts electrons out of alignment.
• Magnetically soft v.s. Magnetically hard

  Magnetically soft metals (iron) gain and lose magnetism easily.

  magnetically hard (Cobalt, nickel) do not magnetize easily but retain that magnetism once achieved
• Magnetic fields

  An area in which a magnetic force can be detected and produced by motion of electric charge

  the earth is protected by a magnetic field.
• Spinning e-

  • in motion around nucleus of atoms creates tiny current a that make magnetic fields

  •tiny magnet pairs spinning in the same way is a stronger magnet

  •opposite directs magnetic fields cancel (magnets electrons spin in the same direction)
• Magnetic domains

  Ferromagnetic materials have e- spins. That do not cancel completely

  atoms near each other group together (net spins are called domains)
• Right hand rule

  Direction of magnetic force is perpendicular to velocity and the magnetic field
• How does a television picture work?

  Cathode ray tub (CRT) charged particles are deflected by magnetic fields. This causes e- to be spread onto the inner surface of the tube giving a picture.

  the charge moving through a magnetic field follows a circular path
• Magnetic force on a current carrying conductor

  Current is a collection of e- in motion and a single e- experiences a force in a magnetic field.

  the current carrying wire experiences a force as well.

  total force is equal to the sum of the forces on each e-

  force on a current carrying wire perpendicular to a magnetic field
• Temporary magnet


  Only magnetizes when exposed to a permanent magnetic field or electric current
• Magnetic fields 


  produced by the motion of electric charge

  more uneven distribution of electrons creates more net charge