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So, i can find my notes and need help. like, now please

  1. Apr 26, 2009 #1
    alright so i just found out ive got a physics test tomorrow and i cant find my notes. can somebody help explain the rules for parallel and series circuits and how to solve them for current, voltage, and resistance? i think thats all i need..

    ps-this is my first post so yay! maybe this will keep me from failing =)
  2. jcsd
  3. Apr 26, 2009 #2
    Signing up to a new forum the night before your exam is likely provide much more of a distraction than a learning aid.

    If you simply google these questions, you'll find plenty of answers.
  4. Apr 26, 2009 #3
    right.. but i googled those questions and links to this forum came up. only they were just answers to some kid's homework, so it didnt really help.
  5. Apr 26, 2009 #4
    Read up on Kirchoff's laws (junction and loop rule) -- Also I'm assuming you have a book? Read it and do practice problem.

    Also try looking up parallel and series resistors, doesn't sound like you're doing capacitors yet.

    Basically in a circuit we have a voltage source, it increases the voltage and everything else (resistors, capacitors, etc) can be thought of as decreasing the voltage. So if you write everything out in terms of voltage the equations should equal 0. Just make multiple loops around the circuit until you have as many equations as unknowns, then just solve.
  6. Apr 26, 2009 #5
    Seconded...these are more commonly referred to as the KVL and KCL


    Also make sure you know Ohm's Law and the rules for adding resistors in parallel and series is described here

  7. Apr 26, 2009 #6


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    The general rules are:

    For series circuits:
    1. The current is the same for all elements.
    2. The voltage drops sum to the source voltage.
    3. Resistances add.

    For parallel circuits:
    1. The voltage is the same for all elements.
    2. The the branch currents sum to the total current.
    3. The sum of inverse of the individual resistors is the inverse of the total resistance.

    In general for series parallel circiut reduce parallel pairs, to get a series circiut.
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