[sdiy] Thevenin's and Norton's Theorems

[Dustin Withers]

Ok so I can build kits and read datasheets but I decided to increase my
knowledge of electricity and since I haven't had a class in many years I've
forgotten all the theory.  Anyhow got a book and got through a fair amount
of it until I got to this Thevenin's and Norton's theory along with Voltage
Deviders and Current Deviders.  I figured I won't get very far not
understanding these theories, so what are they used for?  Are they used just
to figure out E-Out off of a tap between to resistors?  I'm sorry this
question is so vague but I rather confused.  It seems to me you could just
use Ohm's law to figure out what needs to be and what doesn't.  Am I wrong?

Thanks :)

-dustin