Reference direction of electrical current in teaching/books

[eliben]

Hello,

Recently I ran into a book that teaches that current flows from the
negative to the positive terminal (i.e. across a resistor). This
implies electron flow and is opposed to all examples I've seen in
other books.

Perhaps someone knows of a resource that discusses this issue? I.e.
which way is more correct to teach, how have the current symbolics
developed, etc?

Thanks

 

[Rich Webb]

On Sat, 20 Jun 2009 04:15:37 -0700 (PDT), eliben <eliben@gmail.com>
wrote:

Hello,

Recently I ran into a book that teaches that current flows from the
negative to the positive terminal (i.e. across a resistor). This
implies electron flow and is opposed to all examples I've seen in
other books.

Perhaps someone knows of a resource that discusses this issue? I.e.
which way is more correct to teach, how have the current symbolics
developed, etc?

http://amasci.com/miscon/eleca.html#frkel

--
Rich Webb Norfolk, VA

 

[Rich Webb]

On Sat, 20 Jun 2009 05:49:56 -0700 (PDT), larwe <zwsdotcom@gmail.com>
wrote:

On Jun 20, 7:34 am, Rich Webb <bbew...@mapson.nozirev.ten> wrote:

Recently I ran into a book that teaches that current flows from the
negative to the positive terminal (i.e. across a resistor). This

http://amasci.com/miscon/eleca.html#frkel

Is this really what the OP wanted? (Not being argumentative... but it
doesn't really seem to be helpful information, though true).

Well, he does tend to go around the barn and over the fence to get to
the front door. ;-)

--
Rich Webb Norfolk, VA

 

[Tom Biasi]

"larwe" <zwsdotcom@gmail.com> wrote in message
news:b49ad15e-00a1-4dcf-8cb4-d5a4685ad7a5@l32g2000vba.googlegroups.com...
On Jun 20, 7:34 am, Rich Webb <bbew...@mapson.nozirev.ten> wrote:

Recently I ran into a book that teaches that current flows from the
negative to the positive terminal (i.e. across a resistor). This

http://amasci.com/miscon/eleca.html#frkel

Is this really what the OP wanted? (Not being argumentative... but it
doesn't really seem to be helpful information, though true).

OP - Amazingly, I cannot find (in a quick Google) a lucid web
explanation of the concept, but what you want to research is "passive
sign convention". All the good references I could find are in printed
books, nothing online seems to be worth reading.

<http://books.google.com/books?id=5JI-KELPCpgC&lpg=PA39&ots=i-
ZiBLSQLS&dq=passive%20sign%20convention&pg=PA39>

I think the OP would do well reading the material provided by Rich.
It gave enough backround for the OP to answer his own question.

Tom

 

[Electronworks.co.uk]

"eliben" <eliben@gmail.com> wrote in message
news:daedfdd3-af3d-43a9-9339-3c5996a284bd@l8g2000vbp.googlegroups.com...

Hello,

Recently I ran into a book that teaches that current flows from the
negative to the positive terminal (i.e. across a resistor). This
implies electron flow and is opposed to all examples I've seen in
other books.

Perhaps someone knows of a resource that discusses this issue? I.e.
which way is more correct to teach, how have the current symbolics
developed, etc?

Thanks

Try Googling "Conventional current". Conventional current is taught as it is
easier to understand - positive to negative. Flow of electrons is opposite
to conventional current as they are repelled by the negative terminal and
attracted by the positive. Kids cannot understand this..

--
Bill Naylor
www.electronworks.co.uk
Electronic Kits for Education and Fun

 

[Phil Allison]

"eliben"

Recently I ran into a book that teaches that current flows from the
negative to the positive terminal (i.e. across a resistor). This
implies electron flow and is opposed to all examples I've seen in
other books.

Perhaps someone knows of a resource that discusses this issue? I.e.
which way is more correct to teach, how have the current symbolics
developed, etc?

** Search on "conventional current flow":

http://en.wikipedia.org/wiki/Electric_current

http://simple.wikipedia.org/wiki/Electric_current

Lots more to be found.



...... Phil

 

[larwe]

On Jun 20, 7:34 am, Rich Webb <bbew...@mapson.nozirev.ten> wrote:

Recently I ran into a book that teaches that current flows from the
negative to the positive terminal (i.e. across a resistor). This

http://amasci.com/miscon/eleca.html#frkel

Is this really what the OP wanted? (Not being argumentative... but it
doesn't really seem to be helpful information, though true).

OP - Amazingly, I cannot find (in a quick Google) a lucid web
explanation of the concept, but what you want to research is "passive
sign convention". All the good references I could find are in printed
books, nothing online seems to be worth reading.

<http://books.google.com/books?id=5JI-KELPCpgC&lpg=PA39&ots=i-
ZiBLSQLS&dq=passive%20sign%20convention&pg=PA39>

 

[gearhead]

On Jun 20, 7:15 am, eliben <eli...@gmail.com> wrote:

Hello,

Recently I ran into a book that teaches that current flows from the
negative to the positive terminal (i.e. across a resistor). This
implies electron flow and is opposed to all examples I've seen in
other books.

Perhaps someone knows of a resource that discusses this issue? I.e.
which way is more correct to teach, how have the current symbolics
developed, etc?

Thanks

http://en.wikiversity.org/wiki/Passive_sign_convention

 

[John Larkin]

On Sat, 20 Jun 2009 04:15:37 -0700 (PDT), eliben <eliben@gmail.com>
wrote:

Hello,

Recently I ran into a book that teaches that current flows from the
negative to the positive terminal (i.e. across a resistor). This
implies electron flow and is opposed to all examples I've seen in
other books.

Perhaps someone knows of a resource that discusses this issue? I.e.
which way is more correct to teach, how have the current symbolics
developed, etc?

Thanks

The military and some tech schools (Heald, I think) start with
electron flow, and later switch to conventional current. This confuses
the hell out of the students, some of whom never get it right.
Universities (physics, chemistry, engineering) always use conventional
(pos to neg) flow math.

John

 

[John Larkin]

On Sat, 20 Jun 2009 06:53:57 -0700 (PDT), gearhead
<nospam@billburg.com> wrote:

On Jun 20, 7:15 am, eliben <eli...@gmail.com> wrote:
Hello,

Recently I ran into a book that teaches that current flows from the
negative to the positive terminal (i.e. across a resistor). This
implies electron flow and is opposed to all examples I've seen in
other books.

Perhaps someone knows of a resource that discusses this issue? I.e.
which way is more correct to teach, how have the current symbolics
developed, etc?

Thanks

http://en.wikiversity.org/wiki/Passive_sign_convention

From that page:


Here are some basic ground rules:

* All resistors are either positive or negative uniformly. Which means that if you consider one resistor to be positive (which is the common case) then all the resistors are positive.

* At least one source is the opposite sign of the resistors. If only one is present then that is the one.

* Always start by making your loop.


This is insane gibberish.

John

 

[Tim Wescott]

On Sat, 20 Jun 2009 04:15:37 -0700, eliben wrote:

Hello,

Recently I ran into a book that teaches that current flows from the
negative to the positive terminal (i.e. across a resistor). This implies
electron flow and is opposed to all examples I've seen in other books.

Perhaps someone knows of a resource that discusses this issue? I.e.
which way is more correct to teach, how have the current symbolics
developed, etc?

By convention, a resistor's _current_ flows from positive to negative

(note that a power supply 'pumps uphill', and forces current to flow from
negative to positive).

This is (or should be, at least) kept distinct from _electron_ flow,
which is opposite of current. If some tidy-minded person wants to teach
you that current flow and electron flow both go in the same direction,
they do you a disservice by confusing the hell out of you and those
around you when you go talk to the other 99.999% of humanity.

--
http://www.wescottdesign.com

 

[eliben]

The military and some tech schools (Heald, I think) start with
electron flow, and later switch to conventional current. This confuses
the hell out of the students, some of whom never get it right.
Universities (physics, chemistry, engineering) always use conventional
(pos to neg) flow math.

Is it correct to say that there's absolutely no advantage of one way
over the other and it's purely a matter of convention?

Of course, it seems that the accepted symbols follow the pos to neg
flow - for example the diode symbol makes it clear the conduction is
from anode to cathode, and the arrows of transistors also follow
conventional flow.

Eli

 

[John Larkin]

On Sat, 20 Jun 2009 12:07:30 -0700 (PDT), eliben <eliben@gmail.com>
wrote:

The military and some tech schools (Heald, I think) start with
electron flow, and later switch to conventional current. This confuses
the hell out of the students, some of whom never get it right.
Universities (physics, chemistry, engineering) always use conventional
(pos to neg) flow math.


Is it correct to say that there's absolutely no advantage of one way
over the other and it's purely a matter of convention?

It might have been better to call electrons positive, but the
convention pre-dates the discovery of electrons. So it's a convention
we're stuck with.

Things other than electrons can carry current too, like positive ions
and proton beams.

Of course, it seems that the accepted symbols follow the pos to neg
flow - for example the diode symbol makes it clear the conduction is
from anode to cathode, and the arrows of transistors also follow
conventional flow.

Ammeters and voltmeters too.

John

 

[George Herold]

On Jun 20, 12:38 pm, John Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:

On Sat, 20 Jun 2009 06:53:57 -0700 (PDT), gearhead





nos...@billburg.com> wrote:
On Jun 20, 7:15 am, eliben <eli...@gmail.com> wrote:
Hello,

Recently I ran into a book that teaches that current flows from the
negative to the positive terminal (i.e. across a resistor). This
implies electron flow and is opposed to all examples I've seen in
other books.

Perhaps someone knows of a resource that discusses this issue? I.e.
which way is more correct to teach, how have the current symbolics
developed, etc?

Thanks

http://en.wikiversity.org/wiki/Passive_sign_convention

From that page:

Here are some basic ground rules:

    * All resistors are either positive or negative uniformly. Which means that if you consider one resistor to be positive (which is the common case) then all the resistors are positive.

    * At least one source is the opposite sign of the resistors. If only one is present then that is the one.

    * Always start by making your loop.

This is insane gibberish.

John- Hide quoted text -

- Show quoted text -

Yup, that's a pretty crappy article. You can't believe everything you
read on wiki.

George H.

 

[Electronworks.co.uk]

"eliben" <eliben@gmail.com> wrote in message
news:7feb50f7-f093-48dc-8b08-d03881dde78e@n19g2000vba.googlegroups.com...

The military and some tech schools (Heald, I think) start with
electron flow, and later switch to conventional current. This confuses
the hell out of the students, some of whom never get it right.
Universities (physics, chemistry, engineering) always use conventional
(pos to neg) flow math.


Is it correct to say that there's absolutely no advantage of one way
over the other and it's purely a matter of convention?

Of course, it seems that the accepted symbols follow the pos to neg
flow - for example the diode symbol makes it clear the conduction is
from anode to cathode, and the arrows of transistors also follow
conventional flow.

Eli

In 22 years of electronics, I have never met anyone who uses electron flow
as the norm. Keep it conventional - positive to negative - and you will fit
in with the crowd and not confuse the hell out of everyone

(it looks like Phil agrees with me, which gives me a warm feeling too (!))

--
Bill Naylor
www.electronworks.co.uk
Electronic Kits for Education and Fun

 

[Greegor]

EW > (it looks like Phil agrees with me, which gives me a warm feeling
too (!))

Like wetting your pants?

 

[Electronworks.co.uk]

"Greegor" <Greegor47@gmail.com> wrote in message
news:2786c8bd-976d-4ccd-aea7-d9b1a90f924f@l28g2000vba.googlegroups.com...

EW > (it looks like Phil agrees with me, which gives me a warm feeling
too (!))

Like wetting your pants?

!!!!

Now that made me laugh!

--
Bill Naylor
www.electronworks.co.uk
Electronic Kits for Education and Fun

 

[stan]

On Jun 22, 8:04 am, "Electronworks.co.uk"
<newsgro...@electronworks.co.uk> wrote:

"Greegor" <Greego...@gmail.com> wrote in message

news:2786c8bd-976d-4ccd-aea7-d9b1a90f924f@l28g2000vba.googlegroups.com...

EW > (it looks like Phil agrees with me, which gives me a warm feeling
too (!))

Like wetting your pants?

!!!!

Now that made me laugh!

--
Bill Naylorwww.electronworks.co.uk
Electronic Kits for Education and Fun

It's easy. Electrons are negative and are attracted to the positive.
Understand that (as in electron tubes or semi conductors) and put it
aside.
Now; as a convention it was decided long ago that current flow within
an electric circuit shall be shown as flowing from postive to
negative.
For example:
Positive terminals on things such as batteries are often marked or
shown in red. Negative terminals in various other colours, often
black, green. blue etc. When working on a circuit one assumes electric
current flows away from the positive part of any circuit towards
something less positive or in other words negative to the starting
point.

 

[Rich Grise]

On Sat, 20 Jun 2009 04:15:37 -0700, eliben wrote:

Recently I ran into a book that teaches that current flows from the
negative to the positive terminal (i.e. across a resistor). This
implies electron flow and is opposed to all examples I've seen in
other books.

Perhaps someone knows of a resource that discusses this issue? I.e.
which way is more correct to teach, how have the current symbolics
developed, etc?

College boys use positive charge flow - techies use electron flow.
(electron flow is clearly right - consider the CRT! ;-) )

Just remember which system you're using, and be consistent - they're
identical, but with all the signs swapped.

Hope This Helps!
Rich

 

[Rich Grise]

On Sat, 20 Jun 2009 09:35:50 -0700, John Larkin wrote:

On Sat, 20 Jun 2009 04:15:37 -0700 (PDT), eliben <eliben@gmail.com

Recently I ran into a book that teaches that current flows from the
negative to the positive terminal (i.e. across a resistor). This
implies electron flow and is opposed to all examples I've seen in
other books.

Perhaps someone knows of a resource that discusses this issue? I.e.
which way is more correct to teach, how have the current symbolics
developed, etc?

Thanks

The military and some tech schools (Heald, I think) start with
electron flow, and later switch to conventional current.

Not in the USAF, they didn't. We used electron flow from the
start, and stuck with it. It's really the only way to understand
how maagnetrons and klystrons and traveling wave tubes and backward
wave oscillators and such actually work. >:->

Either way works equally well, just swap all of the plus and
minus signs. ;-)

Cheers!
Rich