definition: voltage, current

P

Paul Mars

Guest
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,
p
 
"John Fields" <jfields@austininstruments.com> wrote in message
news:pph211ld038a6vl28p270bd8d4buaa2c4v@4ax.com...
On Tue, 15 Feb 2005 00:37:27 GMT, "Genome" <ilike_spam@yahoo.co.uk
wrote:
The charge on an electeron was worked out by Millikan (sp)

---
Pity his name wasn't Attodecikan...
---
John Fields
Click to expand...
No......! I shit you not.

The bloke was an American.

He went and suspended droplets of something that he charged up in an
electric field (no pun intended) and measured something versus something
like gravity or another thing (how fast it went up and down) and it was dead
sensitive and they all came out to be multiples of the charge on an
electeron and he found the smallest one was 1.6-19C or something.

It was a classic experiment.

DNA
 
Has the OP given his friend the hydralogical analogy yet? Volts is PSI
in the hose and Amps is gallons per minute, the size of the hose is the
resistance of the wire. Seems intuitive.
 
"Lord Garth" <LGarth@Tantalus.net> wrote in message
news:dCdQd.30583$wi2.8442@newssvr11.news.prodigy.com...
Virtual Millikan: http://www68.pair.com/willisb/millikan/experiment.html
Click to expand...
Monster,

"Millikan first let them fall until they reached terminal velocity. Using
the microscope, he measured their terminal velocity, and by use of a
formula, calculated the mass of each oil drop."

But..... I think that's wrong.

DNA
 
On Tue, 15 Feb 2005 00:37:27 +0000, Genome wrote:

The charge on an electeron is 1.6019dribblydribblyE-19 Coulombes.
Multiply that by Johns number of electerons and you get 1...ish.

The charge on an electeron was worked out by Millikan (sp)
Click to expand...
This last election, I heard that the electerons were charging
five bucks a vote!
--
Pig Bladder On A Stick
Still waiting for some hot babe to
ask what my favorite planet is.
 
On Mon, 14 Feb 2005 00:40:56 -0600, Ratch wrote:

Charge exists in two flavors, positive and negative.
Click to expand...
Stephen Leacock?

--
Then there's duct tape ...
(Garrison Keillor)
 
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,
Click to expand...
---
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
 
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
Click to expand...
 
"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
Click to expand...
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
 
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
Click to expand...
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.
 
"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:

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.

John Fields
Click to expand...
Indeedy, sort of. The Ampere was/is defined as 1 Coulombe per second of
charge passing by.

It has something to do with electrochemistry and deposition of a Molseworth
of Avogadros somesuch somewhere else.

mole junior ask brane, 'if you are so clev wot is one plus one?' at which
point brane larf so much it burst into a trillion pieces.

The charge on an electeron is 1.6019dribblydribblyE-19 Coulombes. Multiply
that by Johns number of electerons and you get 1...ish.

The charge on an electeron was worked out by Millikan (sp)

Blame the Chemists.

DNA
 
On Tue, 15 Feb 2005 00:37:27 GMT, "Genome" <ilike_spam@yahoo.co.uk>
wrote:

"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:

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.

John Fields

Indeedy, sort of. The Ampere was/is defined as 1 Coulombe per second of
charge passing by.

It has something to do with electrochemistry and deposition of a Molseworth
of Avogadros somesuch somewhere else.

mole junior ask brane, 'if you are so clev wot is one plus one?' at which
point brane larf so much it burst into a trillion pieces.

The charge on an electeron is 1.6019dribblydribblyE-19 Coulombes. Multiply
that by Johns number of electerons and you get 1...ish.

The charge on an electeron was worked out by Millikan (sp)
Click to expand...
---
Pity his name wasn't Attodecikan...
---

Blame the Chemists.
Click to expand...
---
I'll raise me cup to that one!

--
John Fields
 
On Tue, 15 Feb 2005 01:29:53 GMT, "Genome" <ilike_spam@yahoo.co.uk>
wrote:

"John Fields" <jfields@austininstruments.com> wrote in message
news:pph211ld038a6vl28p270bd8d4buaa2c4v@4ax.com...
On Tue, 15 Feb 2005 00:37:27 GMT, "Genome" <ilike_spam@yahoo.co.uk
wrote:
The charge on an electeron was worked out by Millikan (sp)

---
Pity his name wasn't Attodecikan...
---
John Fields

No......! I shit you not.

The bloke was an American.

He went and suspended droplets of something that he charged up in an
electric field (no pun intended) and measured something versus something
like gravity or another thing (how fast it went up and down) and it was dead
sensitive and they all came out to be multiples of the charge on an
electeron and he found the smallest one was 1.6-19C or something.

It was a classic experiment.

DNA
Click to expand...
---
Milli = 1 times ten to the minus three so Millikan, with a name like
that, should have only been able to measure to one part in a thousand.

However, his exquisite experiment yielded results sixteen orders of
magnitude greater than one part in 1000, so if his surname would have
been Attodecikan, it would have fit his accomplishment. :)

--
John Fields
 
"John Fields" <jfields@austininstruments.com> wrote in message
news:tqk211h1rjvv9uc4e5h2ijvo7hainakfln@4ax.com...
On Tue, 15 Feb 2005 01:29:53 GMT, "Genome" <ilike_spam@yahoo.co.uk
wrote:


"John Fields" <jfields@austininstruments.com> wrote in message
news:pph211ld038a6vl28p270bd8d4buaa2c4v@4ax.com...
On Tue, 15 Feb 2005 00:37:27 GMT, "Genome" <ilike_spam@yahoo.co.uk
wrote:
The charge on an electeron was worked out by Millikan (sp)

---
Pity his name wasn't Attodecikan...
---
John Fields

No......! I shit you not.

The bloke was an American.

He went and suspended droplets of something that he charged up in an
electric field (no pun intended) and measured something versus something
like gravity or another thing (how fast it went up and down) and it was
dead
sensitive and they all came out to be multiples of the charge on an
electeron and he found the smallest one was 1.6-19C or something.

It was a classic experiment.

DNA
Click to expand...
Virtual Millikan: http://www68.pair.com/willisb/millikan/experiment.html
 
"John Fields" <jfields@austininstruments.com> wrote in message
news:tqk211h1rjvv9uc4e5h2ijvo7hainakfln@4ax.com...
On Tue, 15 Feb 2005 01:29:53 GMT, "Genome" <ilike_spam@yahoo.co.uk
wrote:


"John Fields" <jfields@austininstruments.com> wrote in message
news:pph211ld038a6vl28p270bd8d4buaa2c4v@4ax.com...
On Tue, 15 Feb 2005 00:37:27 GMT, "Genome" <ilike_spam@yahoo.co.uk
wrote:
The charge on an electeron was worked out by Millikan (sp)

---
Pity his name wasn't Attodecikan...
---
John Fields

No......! I shit you not.

The bloke was an American.

He went and suspended droplets of something that he charged up in an
electric field (no pun intended) and measured something versus something
like gravity or another thing (how fast it went up and down) and it was
dead
sensitive and they all came out to be multiples of the charge on an
electeron and he found the smallest one was 1.6-19C or something.

It was a classic experiment.

DNA

---
Milli = 1 times ten to the minus three so Millikan, with a name like
that, should have only been able to measure to one part in a thousand.

However, his exquisite experiment yielded results sixteen orders of
magnitude greater than one part in 1000, so if his surname would have
been Attodecikan, it would have fit his accomplishment. :)

--
John Fields
Click to expand...
Thanks for explanation.

No offence meant to you or owners thereoff.

DNA
 
On Sun, 13 Feb 2005 22:13:27 -0500, Paul Mars wrote:

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.
Click to expand...
Voltage is defined as the potential difference between two points. The
"period" is a punctuation mark.

Potential is like pressure.

When you compress a spring, you give it potential energy, which it
stores up in the form of the stress on the spring itself. When you
release the spring, that energy is released as "kinetic energy", but
that's another topic.

The point is, that "potential" corresponds to "pressure." It's
something like water flowing downhill, where the "potential energy" is
represented by the height of the water column - actually, the height is
the voltage - the current, obviously, is the flow, and the power is
the pressure times the flow.

Now, if you just let the water fall, then the analogy to an electronic
circuit kind of breaks down, except that a waterfall might be kind of
conceptually like an arc.

But if it falls through a waterwheel, then you can extract energy from
it. The amount of energy you can extract at any given moment can be
expressed as (or derived from?) the flow rate multiplied by the pressure
difference. No, wait - rate - that's the rate at which you're extracting
energy. Energy and work are almost interchangeable - I had a physics
teacher who said, "Energy is the capacity to do work." Work, of course, is
force times distance. And power is the rate of doing work.

Hope This Helps!
Rich
 
"Rich Grise" <rich@example.net> wrote in message
news:pan.2005.02.15.22.28.16.338210@example.net...
On Sun, 13 Feb 2005 22:13:27 -0500, Paul Mars wrote:

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.

Voltage is defined as the potential difference between two points. The
"period" is a punctuation mark.
Click to expand...
No it is not defined that way. It is often confusingly described that
way. Potiential of what?

Potential is like pressure.
Click to expand...
In what way? Force per unit area vs energy per coulomb!?

When you compress a spring, you give it potential energy, which it
stores up in the form of the stress on the spring itself. When you
release the spring, that energy is released as "kinetic energy", but
that's another topic.
Click to expand...
No potential energy is converted into kinetic energy unless you propel
something like a pinball. It could just as easily be converted into heat by
connecting it to a dashpot.

The point is, that "potential" corresponds to "pressure." It's
something like water flowing downhill, where the "potential energy" is
represented by the height of the water column - actually, the height is
the voltage - the current, obviously, is the flow, and the power is
the pressure times the flow.
Click to expand...
Does the above description help anyone to really understand what
voltage is? Ratch

Now, if you just let the water fall, then the analogy to an electronic
circuit kind of breaks down, except that a waterfall might be kind of
conceptually like an arc.

But if it falls through a waterwheel, then you can extract energy from
it. The amount of energy you can extract at any given moment can be
expressed as (or derived from?) the flow rate multiplied by the pressure
difference. No, wait - rate - that's the rate at which you're extracting
energy. Energy and work are almost interchangeable - I had a physics
teacher who said, "Energy is the capacity to do work." Work, of course, is
force times distance. And power is the rate of doing work.

Hope This Helps!
Rich
Click to expand...
 
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