ELEC 242 Lab
Interlude
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So far,
the signals we have observed have been simple,
and their sources assumed to be ideal.
Similarly, we have assumed that the measuring instrument had no effect
on the signal source.
Real signal sources and destinations
are not ideal, but rather have a resistance associated with them,
as shown in the diagram below.
For resons which will soon become apparent,
it's common to refer to the destination of a signal as the
load.
Ordinarilly we assume that 
is negligably small (e.g. 0)
and that 
is extremely high (e.g. 
).
This assumption usually works
but sometimes fails, causing
"anomolous results".