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Re: Voltaic Pile of Confusion



At 16:17 7/29/00 -0400, Tom McC wrote:
I have been reading an account of Volta's reasoning for creating a pile and
I don't think it is quite right (this is not Volta's reasoning but the
author's interpretation of it). If one cell generates a given current,
then several cells connected in series would produce a larger current under
the same conditions. I would think this should read voltage, rather than
current. The current would remain fixed but it would be more energetic.
What do y'all think?...

Tom McCarthy

Let me see if I can recreate the author's thoughts, given only this
fragment.

Some cell generates a terminal voltage of x volts with r internal
resistance, off-load.
Connected to some external load of resistance R, it produces
a current of I1 = x/(r+R)

Now two such cells are connected in series to the same load resistance.
The current is now I2 = 2x / (2r+R)

I conclude this current is greater than the first.

The loaded terminal voltage of the cell in the first case is x - I1.r
In the second case each cell meters at x - I2.r

I conclude that this terminal voltage is smaller than with the single cell.

Hence we might suppose that Volta reasoned that when a second cell is added
in series to a first cell supplying a load, the terminal voltage of each
cell falls, but its current rises.

I expect Tom's conclusions were diametrically opposite to those shown here
because when he read "under the same conditions" he chose different
parameters to be held constant.



brian whatcott <inet@intellisys.net> Altus OK
Eureka!