I'm trying to understand why the voltage across parallel circuit elements is the same. I keep finding the answer "because they are both connected to the same voltage source." Why is it the case, in a physical sense, that voltage MUST be the same across, say, capacitors that are connected in parallel to the same voltage source? How does this physically dictate the same potential difference existing across each capacitor in parallel? I have other questions about voltage and circuits, but I will hold off on them and see where this example takes us. Thanks for any help!