My official students are studying electromagnetics this quarter. Last week, they started on capacitors. The moment I learned that, I stopped my student in the middle of her sentence (so rude of me) and said, “Okay, I have something to write out for you. We might not use it immediately, but we will use it soon, and we will keep using it. You will probably use it later in your engineering electronics classes. It will be your best friend.”
What I meant was The Chart. The Chart organizes the basic rules for resistors and capacitors together for reference and reinforcement. I’m usually adjusting it for circumstances, but very little of it really changes.
It wasn’t more than 10 minutes of work before I got to say, “Well, let’s look at The Chart… Oh! There’s our answer!” to which I got the most gratifying reply: “The Chart really is my friend!”
Totally made my day.
The biggest problem people usually have with this is remembering that they have to flip the result of the right side of the “weak” equations. Using and checking units is the main way to fix this. Another way is a shortcut for two capacitors or resistors:
Ceq = (C1 C2)/ (C1 + C2)
You can check this one with units, too: Farads squared on top divided by Farads gives Farads.
That’s all for now. Send me questions and puzzles!