Re: definition: voltage, current

From: Kevin Aylward (salesEXTRACT_at_anasoft.co.uk)
Date: 02/14/05 

Date: Mon, 14 Feb 2005 07:22:03 GMT

Ratch wrote:
> "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

Yes!

I was going to quibble with force on this one, but you done the job fine
Ratch:-)

Kevin Aylward
salesEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

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