One can put together a little kit to experiment with the equilibrium condition and see how it is affected by changes using the simplified circuit below.
It's easier to deal with resistances and one can derive similar formulas for the equilibrium condition and its changes. The relative change formula is approximately true also. The slight difference in formulas is due to the fact that in the electrical circuit both resistances affect the flow of electrons.
Pushing the button approximately doubles VB which rapidly returns to normal when it is released. Note the difference in the RC time constants for charging and draining the capacitor. The subscripts for the resistors stand for "source" and "drain".