Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The accurateness of electricity laws

  1. Oct 22, 2010 #1
    Are the mathematical electrical laws as accurate as mechanics laws, if the input is perfect enough, or they're just good approximations??

    I mean ohm's law and potential difference = electric field times length of wire (in wires), and alike laws.
     
  2. jcsd
  3. Oct 22, 2010 #2
    All of maxwells equations are fantastically accurate - more than the precision of our measurements.

    Depending on your philosophy on this subject, you can say that maxwells laws describe exactly electromagnetic behavior, but that we are never able to input the exact parameters needed for an exact answer.
     
  4. Oct 22, 2010 #3
    Well, that was helpful, but I am more concerned to the laws mentioned in post #1
     
  5. Oct 22, 2010 #4

    Dale

    Staff: Mentor

    Maxwell's equations are approximations to quantum electrodynamics (QED) which are suitable whenever quantum effects are not important. AFAIK, there are no known EM phenomena which are not correctly modeled by QED.

    Ohm's law is essentially just the definition of resistance, so it is true by definition.
     
  6. Oct 22, 2010 #5
    OK, for the sake of making the question clearer, Do ohmic materials have perfectly linear relationships of V/I
     
  7. Oct 22, 2010 #6

    Dale

    Staff: Mentor

    No. The resistance is always V/I, but the resistance may itself be a function of voltage or current or temperature or pH or illumination or many other factors.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook