current "flow"

Discussion in 'General Electronics Chat' started by stirling, Feb 20, 2012.

  1. stirling

    Thread Starter Member

    Mar 11, 2010
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    I raised my head above the parapet in http://forum.allaboutcircuits.com/showthread.php?t=66245 but was told I was off topic so I thought I'd reply to my fellow posters here instead.

    OK gentlemen - I'll stick my head back in the lion's mouth.

    Current flows? - we ALL know (right?) that current is a measure of the FLOW of charge (coulombs/sec). No-one would say (would they?) that "flow of charge flows". If they did - wouldn't that be confusing? So why is it so common to see "current flows"? Maybe it's because at best we're lazy and at worst it's because we don't understand what's actually going on. If WE don't understand HOW can we possibly teach? Just because "everyone" says something, doesn't mean it's correct. Giving "youngsters" a totally illogical, inconsistent and confusing premise can't be right can it?

    Your comments:

    I'm not suggesting we do say charge flow. But why do we need the word FLOW in your sentence above - we can talk about current in terms of magnitude and direction perfectly adequately without using the word FLOW. Wouldn't your sentence be just as easy to read AND at the same time more correct and logical if we said: "current is flow of charge, however we always talk about direction of current, not charge flow"

    REALLY? ... perhaps you've proved my point for me.

    Done my best.

    Is it purism to try to get and TEACH things right? If we commonly said things in our schools like "How fast is speed?" or "How far away is that distance" would it not be confusing and would it be purism to correct it?

    (BTW - having skimmed the article you attached it appears to be about a DIFFERENT misconception - NOT what I'm discussing here).

    Look - I'm absolutely NO expert in electronics - you guys have probably forgotten more than I know about electronics. What I DO know is when I first read a decent explanation of this (and others) - "things" started to slot into place and make MUCH more sense to me. Who knows - it may work for someone else.
     
  2. t_n_k

    AAC Fanatic!

    Mar 6, 2009
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    I take your point. "Flow" is redundant & perhaps confusing with respect to "Current".

    I suggest that the point might be lost in translation for many folk who don't have English as their first language.

    There is a great deal of jargon that some people immersed in electronics often use with 'reckless abandon'. I remember one of my teachers suggesting we might consider putting a few "puffs" of capacitance in a circuit for a particular reason. I've no doubt we all fall prey to the use of jargon equally as confusing as the one you mention.

    Consider the endless discussion that arises over the use of terms like earth and ground.

    We can probably all benefit by a more careful use of electrical terminology. I doubt your protests will change years of habit. You'll note the AAC books use electron flow in preference to conventional current - a habit I will likely never acquire.
     
  3. pilko

    Senior Member

    Dec 8, 2008
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    Electric current -- The flow of electric charge carriers.
    Water current --- The flow of water.
     
  4. t_n_k

    AAC Fanatic!

    Mar 6, 2009
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    Which, I think agrees with stirling's point that it is perhaps unhelpful to state for instance, that current flows in a pipe.

    As one electronics web site I found rather curiously has it ...

    "One primary trait of electric current is its rate of flow."
     
  5. Wendy

    Moderator

    Mar 24, 2008
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    Just curious, ever looked up the definition of an amp?

    One definition, excerpted from Wikipedia,

    Given that electrons are not the only charge carrier (just the primary ones) there will be other definitions, but this one is valid. Sure sounds like flow to me.
     
  6. stirling

    Thread Starter Member

    Mar 11, 2010
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    t n k - thanks - crickey - do I have an allie?

    Bill - again I think you make my point for me. What is flowing? and what is the MEASURE of that flow?

    A car travels at 10mph. What is travelling? The car or the mph?
     
    Last edited: Feb 20, 2012
  7. MrChips

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    Oct 2, 2009
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    You mean like flow rate and baud rate and slew rate?
     
  8. stirling

    Thread Starter Member

    Mar 11, 2010
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    LOL - I find it safer to tilt at only one windmill at a time.

    BUT - flow rate and baud rate - yes - same error - but two (or more) wrongs don't make a right (but it is a common distraction tactic in discussion :rolleyes:)

    However slew rate is correct.
     
  9. MrChips

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    Oct 2, 2009
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    Whew! Thanks for the clarification. I was worried for the moment that this was going to become another diatribe on current vs electron flow but instead turns out to be only a pedantic display of semantics.
     
  10. Brownout

    Well-Known Member

    Jan 10, 2012
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    Current has been flowing for hundreds of years, and will continue to flow. I see no confusion as a result of the description or from the logical meaning. Frankly, being anal about tried and true descriptions of how electrical phenomena work in unhelpful to anyone.
     
  11. stirling

    Thread Starter Member

    Mar 11, 2010
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    Actually - I take back what I said about flow rate and baud rate - your distraction technique worked and got ME confused.

    FWIW though I'm sorry that you think what I'm saying is pedantic or just semantics. Perhaps it just shows you still haven’t understood the point and that you still think that current flows, just like speed travels.

    However - as my dear old Gran said: "You can't teach a horse to sing - it frustrates you and annoys the horse". Sorry we couldn't keep this civilized.
     
  12. MrChips

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    Oct 2, 2009
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    Well,
    baud = bits/time, e.g. 9600 bits/sec
    slew = volts/time. e.g. 100V/us

    So wouldn't baud rate and slew rate be other examples of redundancy?
     
  13. Brownout

    Well-Known Member

    Jan 10, 2012
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    Not as far as I'm concerned. Baud is Binary Audio Unit of Data. Baud rate is BAUD/T. Slew is change in output voltage. Slew rate is Slew(V)/T

    I've never found an instance where questioning traditional descriptions ever really made any sense.
     
  14. t06afre

    AAC Fanatic!

    May 11, 2009
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    To be very picky it is actually possible to send more than one bit pr baud ;)
     
  15. Brownout

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    Jan 10, 2012
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    Here's a good case where an explanation of terminology would be very helpful. Bits vs Baud is one thing I think can actually trip someone up.
     
  16. MrChips

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    Yes, I'm aware of the difference but now we're going waaay off topic.
     
  17. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    You could say that there exists some current in R1, but isn't it much more straightforward to say that the current flows through R1?
    This also gives you a hint that this current has to come from somehere into this resistor and leave to somewhere else too.
    Hence if current flows through a resistor, there also has to be a flow of current.
     
  18. t06afre

    AAC Fanatic!

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    Well, yeah no need to beat a dead horse. But to stay on topic. In electronic a jargon has developed. Like saying piffs, or puffs. And also applying a fingernail of goodwill. I can understand 99.99% of every posting made in this forum. The 0.01% is most often written by certain member. But on the other hand those post are quite entertaining in their own bizarre way.
     
  19. Wendy

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    Mar 24, 2008
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    Electrons, of course. They are discrete particles of matter, they exist. They can be ballistic in a vacuum, though they will respond to electric and magnetic fields. In the absence of a electric or magnetic field they will move in a straight line. In a gravitational field they will fall. A vacuum tube or a sputtering machine could not exist if this were not so, along with many other machines.

    As for speed in a vacuum, that is a variable. They have mass. They interact closely with photons, but they are not photons. They are the charge carriers in a wire, and yes, they do move in a wire. Several inches per hour usually. Being subatomic particles they are very small, so huge numbers can exist in a small space, such as the number used in the definition of an amp.

    With other circumstances there can be other charge carriers, but for most of our applications electrons are it.

    MPH is a unit of speed. So is C, along with being a rather important constant. When you use the measurement of speed for the car you are describing a variable property, so your question is meaningless. Speed, as defined by distance over time, is a description of an objects properties. Anything else is trying to muddy the waters and confuse very simple ideas.

    These arguments are well and good with people who understand some physics. They are inappropriate for people who are working on building their understanding so they can work for a living later. You will find many concepts in electronics that are not true, but are used to build concepts that can be changed and build on later, such as AM modulation.
     
    Last edited: Feb 20, 2012
  20. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    I would have to agree with stirling here, as "current" is already describing a "flow" then a "current flow" is the movement of something in motion, and thus a product of the Department of Redundancy Department.

    However, the intent of phrases such as "current flow thru a resistor," while physically incorrect is quite well understood, therefor there is no real need to point out such a distinction.

    The following image may illustrate this point:

    [​IMG]
     
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