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Why does using Conventional Flow work?

  1. Feb 15, 2014 #1
    Hello, I've recently started reading about circuits. It was going good until I got to the idea of Conventional Flow. It confused me so I googled it and I can understand that people are used to it and scientists didn't know what an electron was when they thought about what was going on in circuits. However, I still don't understand when people say it doesn't matter if you use conventional Flow or Electron Flow when designing circuits.

    For example, let's say we had a circuit that looked like this:
    s37kRXA.jpg

    Using electron flow, the electrons would flow from the negative end of the battery,
    go through the resistor and in doing so have it's voltage and current reduced,
    then finally power the light and stop at the positive end of the battery.

    Now if we used conventional flow, the current would flow from the positive end of
    the battery and activate the light first and then have it's voltage reduced by the resistor.
    Wouldn't using conventional flow cause problems in circuit designs seeing as current flows
    as electrons in the opposite direction?

    (I feel like I have some concepts wrong, so with that, please help me learn, thanks. Also, I read the forum guidelines and thought I should post here since it could be counted as "Independent study")
     
  2. jcsd
  3. Feb 15, 2014 #2

    gneill

    User Avatar

    Staff: Mentor

    Potential drops occur as a result of current flow through a resistor. Voltage doesn't "flow", it just is the result of that current flow and resistance. That's the essence of Ohm's Law.

    The light bulb's brightness depends upon the potential drop across it and current flowing through it (note that power dissipated is given by P = I*V). The same magnitude of potential drop occurs across a resistance no matter which direction the given current flows.
     
  4. Feb 15, 2014 #3
    So the presence of the resistor will lower the current for the entire circuit?
     
  5. Feb 15, 2014 #4

    gneill

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    Staff: Mentor

    Exactly. The same current flows through all components in a series-connected circuit.
     
  6. Feb 15, 2014 #5
    Hi, the proper definition of current is the flow of charge. In most cases, the charge carrier is the negatively charged electron, but not always.The flow of a positive charge from positive to negative and the flow of a negative charge from negative to positive are identical and indistinguishable for most purposes. I use conventional flow because I find it easier to think of flow from positive to negative. Also the arrows on diodes and transistors point in the forward biased direction of conventional current flow, which makes it easier for me to understand a circuit's operation.
    And most circuits with one supply, have a positive supply so the normal current flow is from the top (the power) to the bottom (ground) on a schematic.

    As for the Light bulb. Light bulbs also has some resistance and don't forget that the current in a series circuit is everywhere the same.
     

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  7. Feb 15, 2014 #6
    I understand now, I appreciate the help from both of you. Thanks!
     
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