get help?
Let's not get deep into the Electrical Engineering stuff. Be pragmatic if you can.
Look in the American Electricians's Hand book by Terrell Croft, John Watt and Wilford Summers. It eliminates most of the vagaries of electrical principles that you may find in most Electrical Engineering Test Books.
This Handbook is often called The Electrician's Bible. A respected reference by Master Electricians. It also helps a lot for those wannabees.
Look it up yourself on division 3-10. Peruse the division in the article ...and that will really help you.
Lay back on Google and WIKI. It will make you "fat" metaphorically that is...and not to mention getting misguided and confused.