Re: Tesla Coil Operation (getting OT)

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Barton B. Anderson by way of Terry Fritz <teslalist-at-qwest-dot-net>" <classictesla-at-netzero-dot-com>

EMF = electromotive force.

The "force" is the force between electric charges. The electromotive force 
is the voltage potential (or possibility) to do work. When the potential 
difference between 2 charges "forces" a 3rd charge to move, the charge "in 
motion" is an electric current. The "volt" is a measure of the work 
"needed" to move an electric charge. When 0.7376 ft-lb of work is required 
to move 6.25 x 10^18 electrons between 2 points (each with it's own 
charge), the potential difference is 1 volt.
6.25 x 10^18 electrons = 1 coulomb.
0.7376 ft-lb of work = 1 joule, which is the metric unit of work or energy.

John, I agree with the first 3 definitions below, but EMF is not work. EMF 
is only the "potential to do work" and applies either to the voltage 
generated by a source or to the voltage drop across a passive component, 
such a resistor.

I think what is being confused in EMF is the "motive", assuming this 
indicates a charge in motion, which it is not. It is the potential or 
possibility to move a charge. The EMF unit is volt.

It is correctly understood that "1 volt has the potential to do 1 joule of 
work per coulomb of charge". However, often we will read (including text 
books) that "1 volt equals 1 joule of work per coulomb of charge". The 
problem is the word "equals" indicates a possibility to do work, not the 
actual work.

Take care,
Bart

Tesla list wrote:

>Original poster: "John H. Couture by way of Terry Fritz 
><teslalist-at-qwest-dot-net>" <couturejh-at-mgte-dot-com>
>
>
>
>Coulomb is a quantity of electricity, a certain quantity or
>        number of electrons.
>Joules per coulomb means a certain amount of energy in a certain
>        quantity of electricity.
>Charge is an electrical force of attraction or repulsion.
>EMF is work per unit charge. An important characteristic is that
>        this work is reversable. You cannot have an EMF across a
>        resistor.
>
>John Couture
>
>------------------------
>
>
>
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>-----Original Message-----
>From: Tesla list [mailto:tesla-at-pupman-dot-com]
>Sent: Friday, February 21, 2003 12:48 AM
>To: tesla-at-pupman-dot-com
>Subject: Re: Tesla Coil Operation (getting OT)
>
>
>Original poster: "Jolyon Vater Cox by way of Terry Fritz
><teslalist-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>
>
>Joules per coulomb is Joules/charge since a coulomb is a unit of charge.
>By the definition given Joules/charge=Force
>and since  EMF = Joules/ coulomb = Joules/ charge = Force, it follows that
>EMF must be force, and should rightfully be measured in Newtons.
>
>Force itself is not energy.
>Energy is force times distance
>
>If charge in coulombs is equal to the  number of Joules per newton
>this  is the same as saying that charge is energy over force.
>
>Now with Q standing for charge in coulombs, E form energy in Joules, F for
>force in Newtons and d for  distance in metres, Q can be reduced to its
>simplest terms
>
>Q     =    E /F     =    (F x d)/ F     =    F/F x d/F  =d/F
>Q     =     d/F
>
>So, charge is not measured in metres but in metres per newton.
>
>
>Jolyon
>
>----- Original Message -----
>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: <tesla-at-pupman-dot-com>
>Sent: Thursday, February 20, 2003 7:07 PM
>Subject: RE: Tesla Coil Operation (getting OT)
>
>
>  > Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>"
><jimlux-at-earthlink-dot-net>
>  >
>  > At 08:02 AM 2/20/2003 -0700, you wrote:
>  > >Original poster: "John H. Couture by way of Terry Fritz
>  > ><teslalist-at-qwest-dot-net>" <couturejh-at-mgte-dot-com>
>  > >
>  > >
>  > >Ralph -
>  > >
>  > >My physics book gave me yet another meaning for EMF. The book gave units
>for
>  > >EMF as joules per coulomb. This is definitely electrical energy
>  >
>  > Joules == Energy
>  > Joules per anything not= Energy
>  > Joules/charge = Force
>  >
>  > Joules
>  > = watts * seconds
>  > = newtons * meters
>  > = kilograms * meters * meters / (seconds *seconds)
>  >
>  > Force = newtons
>  > = kilograms * meters / (seconds * seconds)  (i.e. F=ma)
>  >
>  > charge = Joules/newtons
>  > = meters
>  >
>  >
>  > So, charge could be measured in meters....
>  >
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