Resistivity and Resistance

• Resistance is the materials ability to resist the flow of electrons, its also measured in ohms meter (ΩM)
• Resistivity values are set depending on the temperature, if the temperature changes so does the resistivity
• • Length
  • Cross sectional Area
  • resistivity
  • Temperature 


  What are the four laws of resistance
• • If the cross sectional area is consistent 
  • As length increases(doubles) so does resistance (this directly proportional) 


  What is the law for length
• • If the length stays consistent
  • Then the area increases
  • resistance decreases (this inversely proportional) is halved)

  What is the law for cross sectional area
• Depends on:

  • What the material is made of
  • The atomic structure
  • The number of electrons within the structure

  What is the law of resistivity
• • The 3 laws are correct as long as the temperature stays constant
  • Resistance increases along side the temperature 

  • Except for carbon, as the temperature increase the resistance decreases

  What is the law of temperature
• R =P x L/A  


  What is the formula for resistance
• • R = Resistance (Ω)
  • p = Resistivity (ΩM)
  • l = Length (m)
  • A = Cross sectional area (m²)


  What is R =(P x L)/A