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Re: reifying energy



Here's the thing: the e field driving the drift velocity of the
charge carriers can be described as the difference in potential
between the supply end of a pair of wires, and their potential
at the load.
If we want that drift velocity to increase, we increase the
potential drop *along* the wires, and one ready way to achieve
this is to reduce the value of the load resistance, which
increases the load, as people like to say.

In the usual case with utilities, where the source impedance
is very much lower than the load resistance we provide,
the supply voltage stays reasonably steady, and to describe
the faster rate of charge transport, we talk of increased current.

If we wished to double the number of charge carriers employed,
we could use thicker wire, or a longer path and still maintain
much the same power consumption.

Brian

At 07:58 PM 5/9/02, you wrote:

But their drift velocity will increase only with an increase in E field
strength in the copper which depends on the potential difference applied
to the wire. An effective PD of 120 volts will create a constant
effective drift velocity. So I say again, the amount of energy you
derive from the power line depends on the number of electrons that are
vibrating.

poj

Brian Whatcott wrote:

>Actually not.
>
>The way that the number of electrons increases across some plane
> [in some time increment] is by increasing their drift velocity - in my
>(always considered) view.
>I take it that the number of mobile charge carriers in the usual course
>of events is a function of the material, its state, and its cumulative
>volume for any reasonable electric field strength - i.e reasonably
>constant.
>
>Brian
>
>At 01:34 PM 5/9/02, you wrote:
>
>>Imagine a swarm of electrons vibrating in a copper wire, Brian. There are
>>two ways that the number of electrons passing a given reference plane in a
>>half cycle can increase: either the number of electrons in the swarm
>>increases or the wavelength of the vibration increases. Since the
vibrationn
>>frequency remains fixed at 60 Hz, the wavelength of a vibration also stays
>>fixed. Therefore, the number of electrons vibrating must increase.
>>
>>poj
>>
>>----- Original Message -----
>>From: "Brian Whatcott" <inet@INTELLISYS.NET>
>>To: <PHYS-L@lists.nau.edu>
>>Sent: Thursday, May 09, 2002 11:44 AM
>>Subject: Re: reifying energy
>>
>>
>>>It is either a discussion gambit or a nit-pick I realise,
>>>but the number of electrons that vibrate is not material,
>>>but rather the number of electrons that pass a reference
>>>plane.
>>>
>>>Brian
>>>
>>>
>>>At 08:32 AM 5/9/02, you wrote:
>>>
>>>>I think we're paying for (1) the potential difference that the utility
>>>>company maintains across the wires at our meter
>>>> (same price for everyone)
>>>>and (2) the number of electrons residing in our household wiring that
>>>>vibrate back and forth at 60 Hz (price depends on number of electrons
>>>> made to vibrate by the loads we switch on).
>>>>
>>>>poj
>>>>

/clip/
Brian Whatcott
Altus OK Eureka!