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

Current does not always choose the path of least resistance...?

  1. Sep 29, 2015 #1
    Hello Forum,

    Electric current usually goes down the path of least resistance if it can. However, there are situations in which it prefers to go through a path of more resistance if the path of least resistance has no potential difference across.
    Are my statements correct?

    For example, see the circuit below where the current does not pass through the red segment of the circuit because it has no potential a difference across and could be removed without affecting the circuit:

    upload_2015-9-29_7-21-55.png

    thanks!
     

    Attached Files:

  2. jcsd
  3. Sep 29, 2015 #2
    Yes, your statement is correct. Current does not always follow the path of least resistance. Your example is a little misguided though.

    Current travels in loops. so the entire loop resistance needs to be considered.

    But suppose we have a 100Ω resistor in parallel with a 99Ω resistor. Some current will flow in each rather than all of it flowing in the path of least resistance, the 99Ω resistor.
    (More will flow in the 99Ω than the 100Ω though.)

    Also there are capacitance, inductance, and occasionally relativistic effects that affect the current flow.
     
  4. Sep 29, 2015 #3

    epenguin

    User Avatar
    Homework Helper
    Gold Member

    It goes through all paths. Some goes through the bird perching on the high voltage electric supply cables. But it goes in the 'laziest' way possible, it goes in such a way that it heats (aka dissipates energy) the least possible, given the constraints. So it mostly goes through the cable not the bird. There was a thread about it by a guy who discovered this (not the first unfortunately) here.
    https://www.physicsforums.com/threads/power-dissipation-in-parallel-circuit.607708/

    You need read only posts 1 and 22.
     
  5. Sep 29, 2015 #4

    donpacino

    User Avatar
    Gold Member

    theoretically yes!

    warning: this is a tangent and not really related to the main point of your post.
    there are times where seemingly useless bits of circuitry or components will exist is a circuit. They will for all normal operating conditions and will not effect operation if removed. In many cases, these components are there for failure prevention or reliability reasons in case of failure.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Current does not always choose the path of least resistance...?
Loading...