Resistor circuit with two batteries
A learner wrote in with this question as she prepared for a physics final. It’s looks complicated. But there’s a trick!
Created by Willy McAllister. (This is the very first video I made for Khan Academy.)
Open this simulation model of the original circuit. Click on DC to perform a DC analysis to find the current.
Another version of the circuit using the ‘trick’ of adding a wire between the two identical voltage nodes. To make the simulator work you have to remove one of the batteries. Notice $i$ has the same value as the original circuit. Notice all the current flows through the one battery.