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Old 6th May 2004, 08:07 PM   #1
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Default an observation on Ohms Law

curious, at what point in time did E transpose to V?

I saw E expressed as V in Ohms law recently and I thought it was a mistake. But when I googled I came across a few sites that express it like this.

I learned that voltage was expressed as E

E= Voltage or (E)nergy
I= Current or (I)ntensity
R= Resistance (obvious)
P= Power (obvious)

P=IE and E=IR or Pie and Eir, Pioneer, get it? snicker snicker (yes my electronics teacher was a super dork). Actually he was smart, he pointed out that its important to not look at E as voltage per se, but as energy, sighting a cross reference to water and air flow. His point was to teach us not to think of Ohms Law as an "electrical" formula, but as a physical law of nature.

I know its just academic, but this was one of those tiny things that helped me to think independently.
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Old 7th May 2004, 08:18 AM   #2
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"curious, at what point in time did E transpose to V?"

Thanks for your observation. I have wondered the same.
By the way ... we must have studied under the same Teacher!
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Old 7th May 2004, 11:25 PM   #3
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as I recall, E usually means "potential" (what it is relative to, I don't recall). so voltage between two points is really the difference between the two points' potential.

or V = delta E.

Potential itself will not cause electrons to flow. But he difference in potential will.
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Old 8th May 2004, 10:51 AM   #4
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Moved to EE, 'cos this is on topic for the site!
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Old 8th May 2004, 11:19 AM   #5
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Quote:
Originally posted by millwood
as I recall, E usually means "potential" (what it is relative to, I don't recall). so voltage between two points is really the difference between the two points' potential.

or V = delta E.

Potential itself will not cause electrons to flow. But he difference in potential will.

Interestingly, in some countries like Sweden and Germany,
we use U for voltage and V for potential. To add to the
confusion, E is often used for the voltage of a voltage source.

Just don't ask me where the U comes from originally, but I
suspect it has its origin in Germany.
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Old 8th May 2004, 12:40 PM   #6
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Quote:
Originally posted by Christer



Interestingly, in some countries like Sweden and Germany,
we use U for voltage and V for potential. To add to the
confusion, E is often used for the voltage of a voltage source.

Just don't ask me where the U comes from originally, but I
suspect it has its origin in Germany.
YES, thats rite 'U' is incarnation of German Engineering.

Compliments to Christer
ampman
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Old 8th May 2004, 12:41 PM   #7
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here in SG for physics class...we have this crappy ohms law wheel thingy...basically it's based om P=VI and V=IR...we dp use E and V interchangeably though...but for clarity...V is used most of the time during theory and test papers...wonder why the E and V thingy...perhaps originally it was like Current...represented by I and has a unit of A...so Potential Difference would be represented by E and measured in V...I dunno..just speculating...
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Old 8th May 2004, 09:03 PM   #8
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I believe it's a difference between physicist's and engineer's conventions is all. Same thing with imaginary numbers: physicists use i, engineer's use j but they're both sqrt(-1).

What else is different -- hmm...tough to remember so far back to university.

**Maybe vector notation--putting the arrow above or below the variable?

**mhos vs Siemens?
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Old 8th May 2004, 10:17 PM   #9
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Quote:
**mhos vs Siemens? [/B]

Hi,

Mho is the reverse of “ohm”, so multiple of them should be smho ???

If I remember well E is used in electrostatics to denote the potential of an electric field and it is used also for electromagnetic emission (i.e antennas): E-field an H-field vectors.

Have a look here:

http://physics.nist.gov/cuu/Units/

and:

http://physics.nist.gov/cuu/Units/units.html

Cheers
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Old 8th May 2004, 10:27 PM   #10
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In Sweden we say U=R*I
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