Tuesday, September 21, 2010

Notes on Magnetism (Blog 6)

page 582 - 589


Several points on our new unit, magnetism:

  • a magnetic field is the distribution of a magnetic force in the area of a magnet
  • two different characteristics of magnetics: north and south --> responsible for magnetic forces
  • north and north (thus, south and south too) magnetic poles repel one another while the opposite poles attract
  • a test compass is a tool to map a magnetic field
  • the Earth is similar to a magnet, since it produces its own magnetic field
  • ferromagnetic metals are metals that are not magnetic, but attract; ex. iron, nickel, and cobalt
  • the Domain Theory of Magnets: all large magnets are made up of many smaller and rotatable magnets, called dipoles, which can interact with other dipoles close by; if dipoles line up, a small magnetic domain is produced
  • Oersted's Principle: charge moving through a conductor produces a circular magnetic field around the conductor
  • RHR #1
  • right-hand rules: hand signs to help predict how magnetic forces act
  • right-hand rule #1 (RHR#1) for conventional current flow: grasp the conductor with the thumb of the right hand pointing in the direction of conventional (positive) current flow; the curved fingers point in the direction of the magnetic field around the conductor 
  • RHR #2
  • right-hand rule #2 (RHR#2) for conventional current flow: grasp the coiled conductor with the right hand such that curved fingers point in the direction of conventional current flow; outside the coil, the thumb represents the northern end of the electromagnet produced by the coil 
  • factors that affect a magnet's strength: current in the coil, number of turns in the coil, type of material in the coil's centre, and the size of the coil

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