This thread got me thinking some more. Here are some abbreviations and simple formulas to demonstrate the relationship between the different values.
I = Current. Measured in Ampheres or, "Amps"
V = Voltage. Measured in Volts.
R = Resistance. Measured in Ohms.
P = Power. Measured in Watts
V = I x R
P = (I)2 x R
Sorry, that "2" is supposed to be an exponent. I - squared. My old computer used to allow me to make superscripts for exponents.
To simplify, P = I x V
Here's a cool link for a voltage-drop calculator:
http://http://www.electronicsteacher.com/electronics-calculator/voltage-drop-calculator.php
Hope that wasn't confusing. I also hope it explains how an FET modifies current, without changing voltage.
--Doc