Resistor placement, +/- rails, and DC current direction

From: mask (netmask_at_gmail.com)
Date: 09/03/04 

Date: 3 Sep 2004 15:57:34 -0700

Hi,

I have two questions.. and they will both make apparent that I'm just
now getting into EE.

I've been reading a soldering book which covers the basics of
soldering, reading/drawing schematics, and very basic EE overall.

There are some things that the author assumes the reader would know..
and unfortuantely, I'm not one of those readers. So, the questions:

The author says several times "The positive and ground rails run from
left to right".. Well.. it seems to me that they don't really "run"
either way.. they're just horizontal lines. As far as I've seen on
most schematics so far, you read the top one from right to left, and
the bottom from left to right. (Typically because the battery is shown
in the center/right with positive going up and ground going down)..

So.. Is that assumption true? That the DC current flows out of the
positive, to the circuit, and then basically makes a CW loop back
around to ground?

Second.. He always starts his schematics off with a switch (upper
right hand corner) and then a LED/resistor. However.. the LED is
always BEFORE the resistor in the flow. How does the resistor resist
anything if the current is hitting the LED first? I guess I don't
understand that part.

And third.. Everywhere I read, says that current flows from Negative
TO positive.. They say that the "Convention is to say that it flows
from positive, because in the start people couldn't see that the
electronics flow from negative to positive" or "Since DC electricity
is the flow of electrons from the negative (-) terminal of a battery
or generator, through a conducting material such as a metal wire, to
the positive (+) terminal, the electricity goes in a complete circuit
from the source and back again"

So.. If it actually flows from negative to positive.. How exactly
does placing a switch right between the circuit and the positive
terminal actually do anything? Shouldn't the circuit be designed as if
the flow was coming from the negative terminal?

Thanks in advanced,

Confusedly yours,

-netmask

(I completely see this post being used as ammunition against me later
in life for being clueless of EE)

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