• A material that lets electrons flow through it is called a CONDUCTOR
  • The molecules of all types of conductors resist the flow of electrons to some degree
  • ELECTRICAL RESISTANCE is a measure of how easy or hard it is for electric current to move through a material
      • Conductors have low resistance
      • Insulators have high resistance (little or no current can move through them)

Factors affecting resistance of a wire

  • Wire length
    • Longer wire equals greater resistance
  • Wire thickness
    • Thick wires equal low resistance
    • Large electric currents can move through thick wires easier
  • Material wire is made of
    • Copper and aluminum have low resistance and are used to carry current over a long distance
    • Tungsten has high resistance so it gets hot as electric current moves through it so it is  used in light bulbs
  • Wire temperature
  • Cooler wire equals lower resistance
  • If the temp. increases, the atoms of the wire are moving faster and the electrons bump into them more making it harder to travel past them in the wire
  • Super-conductors lose all resistance at low temp. e.g. Mercury is a good conductor at room temp. but is a super-conductor at –270 degrees.

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11 years ago

what is brightness(radiation) thermometer? should be supported with diagram. also,what is constant volume gas thermometer? with diagram.what is seabag effect-thermoelectric effect with diagram.what is thermocouple? with diagram. all should be supported by notes. thanks.pls, can i get the answers via my mail?