Thanks, that makes my mental model better. But if I added a resistor to that circuit then the voltage readings would be the same, correct?So if I wanted to vary the voltage to an analog pin depending on the resistance of a wire.How would I then hook it up and calculate the voltage to the pin it?
Ah, then what you want is to look at a voltage divider, where the output voltage (which I guess then becomes your input voltage) depends on the ratio of the two reseistances.In fact, a potentiometer is exactly that, where the "mid-point" actually moves along a long resistor. Pots have 3 connections: the "top" being the input voltage, the "bottom" being ground, and the "moving mid-point" is your variable output. Have a look at this tutorial.
I would be great to have a general rule to calculate the voltage to the input pin. No matter the resistance and the amount of paths the current can flow in.
The reason why I'm confused is that I thought you could only measure voltage between to points and the potential difference between them. But the arduino measures at a specific point; the pin.
no, vOut and GND are at the same level in your drawing.