current "flow"

Thread Starter

stirling

Joined Mar 11, 2010
52
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:

current is flow of charge, however we always talk about direction of current flow, not charge flow
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"

I have no idea what you are trying to say.
REALLY? ... perhaps you've proved my point for me.

Care to elaborate?
Done my best.

The purists want to alert us to a great error in our thinking .....
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.
 

t_n_k

Joined Mar 6, 2009
5,448
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.
 

pilko

Joined Dec 8, 2008
213
Electric current -- The flow of electric charge carriers.
Water current --- The flow of water.
 

t_n_k

Joined Mar 6, 2009
5,448
Electric current -- The flow of electric charge carriers.
Water current --- The flow of water.
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."
 

Wendy

Joined Mar 24, 2008
21,840
Just curious, ever looked up the definition of an amp?

One definition, excerpted from Wikipedia,

In practical terms, the ampere is a measure of the amount of electric charge passing a point in an electric circuit per unit time with 6.241 × 10^18 electrons, or one coulomb per second constituting one ampere.[5]
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.
 

Thread Starter

stirling

Joined Mar 11, 2010
52
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?
 
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Thread Starter

stirling

Joined Mar 11, 2010
52
You mean like flow rate and baud rate and slew rate?
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.
 

MrChips

Joined Oct 2, 2009
19,157
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.
 

Brownout

Joined Jan 10, 2012
2,364
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.
 

Thread Starter

stirling

Joined Mar 11, 2010
52
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.
 

MrChips

Joined Oct 2, 2009
19,157
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?
 

Brownout

Joined Jan 10, 2012
2,364
So wouldn't baud rate and slew rate be other examples of redundancy?

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.
 

Brownout

Joined Jan 10, 2012
2,364
To be very picky it is actually possible to send more than one bit pr baud ;)
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.
 

kubeek

Joined Sep 20, 2005
5,587
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.
 

t06afre

Joined May 11, 2009
5,936
Yes, I'm aware of the difference but now we're going waaay off topic.
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.
 

Wendy

Joined Mar 24, 2008
21,840
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?
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.
 
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ErnieM

Joined Apr 24, 2011
7,991
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:

 
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