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Can Kirchoff's laws and Ohm's law be used on circuits with diodes?

  1. Jul 24, 2013 #1
    1. The problem statement, all variables and given/known data

    Can Kirchhoff's voltage and current laws, and Ohm's law, be used when analysing circuits with constant voltage and current sources, but also diodes?

    I'm trying to analyse such a circuit, and I'm finding that current is flowing backwards through one of the diodes.

    2. Relevant equations

    Kirchhoff's Voltage Law: sum of voltage drops in a closed loop is zero.
    Kirchhoff's Current Law: sum of currents entering a node equals sum of currents leaving a node.
    Ohm's Law: V=IR

    3. The attempt at a solution
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Jul 24, 2013 #2
    Kirchhoff's Laws that is the current law(KCL) and the Voltage law(KVL) is indeed valid everywhere, whether the circuit contains diodes, transistors or any other nonlinear element.

    The thing which is not valid with the nonlinear elements in circuit is the principal of superposition.

    Regarding your question on Ohm's Law, ohm's law is not basically a law. when we say V=IR, means the resistance of the element is constant. For nonlinear elements resistance in not usually important, as V is not linear to I. We still define resistance of nonlinear elements using R-= V/I or R = dV/dI.
     
  4. Jul 24, 2013 #3
    Great, thanks for your reply.
     
  5. Jul 30, 2013 #4
    you are welcome!
     
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