So this is not really a 'solve this problem' question, but, rather, I am trying to understand how they can call ABCDEFA a 'closed loop' even though there is another connection (BE) inside it, and why the equations work.
Keeping in mind that I am still in high school physics, and this is definitely outside the scope of this course (hence I cannot rely on my teachers!), I will attempt to reason it out, using Kirchoff's laws.
The Attempt at a Solution
Why would ABCDEFA be a closed loop? I am assuming that it is because no current can enter or exit the loop?
Could someone explain the actual definition of a closed loop here? If the conductor BE were not present, I would have no problem stating that ABCDEFA were a closed loop. But BE just messes me up!
They use Kirchoff's Second Law to get the first equation (yellow). But up to now I've only encountered single EMF circuits. Could someone direct me to get some intuition about why E2 does not affect this equation?
I can't really reason it out much more... except perhaps the fact that, if we ignore E2 and E3, (hence making it into a single EMF circuit), BE and CD are in parallel, and the voltage drops are the same...
Some help would be much appreciated!