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Understanding current and voltage flow

Discussion in 'General Electronics Discussion' started by Ali8bongo, Jul 17, 2012.

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  1. Ali8bongo

    Ali8bongo

    17
    0
    Jun 2, 2012
    Hi
    I wasn't show which section to put this post in so sorry if it's the wrong section.
    I am new to electronics and before I started any electronica kits I decided its best for me to learn the basics of electronics, so I decided to read starting electronics third edition by Keith brindley. After reading this I know understand how each component works on its own for example capacitors, resistors, transistors and I also understand thing like ohms law but the one thing I don't understand is figuring out which way around a curcuit the voltage and current flow. I have looked at lots of basic circuit diagrams and on none of them I can understand how the current and voltage flow through the circuit, I'm probably just looking at this all wrong but are there any online resources that would explain this to me.
    Thanks in advance for any help.
     
  2. john monks

    john monks

    693
    2
    Mar 9, 2012
    It might be helpful to think of electricity as like water flowing through a garden hose. So in a sense voltage which is electromotive force is pressure like the pressure in a water line. In a hose the greatest pressure is at the faucet, where the water is going in and the hose has a back pressure comparable to resistance in a wire. The pressure is least where the water is flowing out because there is no back pressure. Now if you connect two hoses together you have more back pressure therefore more pressure at the faucet. Pressure does not flow. It can be measured in pounds per square inch just as voltage does not flow. The back pressure is because the hose adds resistance to the flow of water and the greater the flow the greater the back pressure. This is comparable to the resistance in a wire.
    Now for ohms law I strongly suggest you ignore it until you fully comprehend the concept of electric current and voltage. This is where most people become confused. Look only at the concepts and ohms law will become obvious.
    Now for concepts, if you have a given rate of water flowing through a hose you will have a certain pressure at the faucet. If you double the length of the hose and still maintain the same rate of water going into the hose you will have exactly twice the amount of back pressure in the hose.
    A similar thing happens in an electric circuit.
    If you have a given amount of current flowing through a resistance you will have a certain amount of pressure needed to propel the electrons through the resistance. Now if you double the resistance you will double the pressure or voltage on the resistance.
    Just talking about this is of little help. You need to get some batteries, small light bulbs, hookup wire, and a voltmeter and experiment with this.
    For more help go to the Tutorials section if the page.
     
  3. shrtrnd

    shrtrnd

    3,808
    511
    Jan 15, 2010
    The visualization of the direction of current flow depends on if you're trained as a technician
    or as an engineer.
    I've had plenty of run-ins with engineers in discussions about this.
    Technicians are trained to think in terms of electron flow, engineers are trained to think
    in terms of 'hole-flow', (the electrons move one way, the 'hole,' or absence of electrons
    in the other direction).
    You can look up those terms 'electron flow' vs. 'hole flow', to see what that means.
    When talking to most people, the current flow is usually discussed in terms of 'hole flow',
    But if you run into disagreements, that's the difference.
     
  4. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
    651
    May 8, 2012
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