1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Current Source in Parallel with Short Circuit

  1. Dec 13, 2014 #1
    1. The problem statement, all variables and given/known data

    Which of the following are self-contradictory combinations of circuit elements?

    - A 2 Amp current source in parallel with a short circuit.

    2. Relevant equations

    KVL- "the sum of voltages around a closed loop amounts to 0.
    KCL- "the current into a node equals the current out of a node.
    Ohm's Law- V= IR

    3. The attempt at a solution

    The answer key says this is not contradictory, but I don't see how we can have such a circuit... If we had a short circuit parallel to a current source wouldn't all the current go into that short circuit branch and ignore the other branches? Then we'd just have a loop of 2 Amp current with no voltage drop... Why wouldn't that violate KVL?
  2. jcsd
  3. Dec 13, 2014 #2


    User Avatar
    Homework Helper

    An ideal current source provides a given current no matter what the load is. The voltage across it is equal to the generator current multiplied by the loading resistance, zero for a short-circuit. Where is contradiction?
  4. Dec 13, 2014 #3


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    What are the other choices you're given?
  5. Dec 13, 2014 #4
    I just always thought that in order for current to flow between two points we need a voltage difference...

    I understand the rest of them... It was only this one I was hung up on
  6. Dec 14, 2014 #5


    User Avatar
    Homework Helper

    What is the voltage difference across zero resistance according to Ohm's Law?
  7. Dec 14, 2014 #6
    V=IR so V=I*0=0. Ok I think I see now
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted