Re: definition: voltage, current

From: Ratch (Watchit_at_comcast.net)
Date: 02/14/05 

Date: Mon, 14 Feb 2005 00:40:56 -0600

"Paul Mars" <paulmarsREMOVE@netzero.com> wrote in message
news:11105q6r6vdkm3a@corp.supernews.com...
> Please do and throw in the Watt please.
>
> BTW Your definition is more logical then what I learned. If you would like
> please comment on voltage being defined as the potential difference
between
> two points period.
>
>
> "John Fields" <jfields@austininstruments.com> wrote in message
> news:iauv01tss5qibckoug0fj06rk7t9h0qeo0@4ax.com...
> > On Sun, 13 Feb 2005 19:46:59 -0500, "Paul Mars"
> > <paulmarsREMOVE@netzero.com> wrote:
> >
> >>
> >>I was trying to explain to a friend what they are and what the
difference
> >>is. My schooling in Electronics was so long ago. I feel that I still
have
> >>a
> >>very good grasp of what they are, but I could not explain them.
> >>
> >>My friend looked them up and got this:
> >>
> >>current (as in "electrical phenomenon") n. : a flow of electricity
through
> >>a
> >>conductor; "the current was measured in amperes"
> >>voltage (as in "electrical phenomenon") n. : the rate at which energy is
> >>drawn from a source that produces a flow of electricity in a circuit;
> >>expressed in volts
> >>
> >>this is WRONG. Please help,
> >
> > ---
> > We define current to be the number of electron equivalent charges
> > moving past a fixed point in a specified interval of time, and we have
> > named the unit of charge transfer the ampere, one ampere being equal
> > to 6.24E18 electron equivalent charges moving past an arbitrary
> > reference point in one second.
> >
> > We define voltage to be the force required to cause charge to move
> > through/against a resistance, with one volt of force being defined as
> > that force necessary to make 6.24E18 electron equivalent charges pass
> > through a resistance of one ohm in one second.
> >
> > Since, then, a resistance of two ohms would require twice the force to
> > cause a flow of charge equal to one ampere to occur, we can write:
> >
> > E 2V
> > I = --- = ---- = 1A
> > R 2R
> >
> > where I is the current, E is the voltage and R is the resistance.
> >
> > There's still a lot left to consider, the coulomb and the joule for
> > example. Do you want to go on?
> >
> > --
> > John Fields
>
>
     Charge exists in two flavors, positive and negative. When it moves, as
the negative electrons in a wire, or positive or negative ions in
electrochemistry, it is called a current. It takes energy to move charges
from on place to another. The amount of energy per unit charge is voltage.
If it takes 5 joules of energy to bring 1 coulomb of charge from point A to
point B, then the voltage of point B with respect to point A will be -5
volts. Think of voltage as the amount of energy per unit charge, not force.
Voltage does produce a electrostatic field which repels or attracts a unit
charge with a finite force, but voltage by itself is not force. Wattage is
simply energy transferred per unit of time. Any good electrical text will
describe what I wrote in more detail. Ratch

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