[Coda]

Originally Posted by Potironette

Oh, so voltage is a measurement. Err, so at one point of a circuit voltage and potential energy is something. At another point in comparison to that point it might be something else. Voltage is a measurement of potential...but what is potential energy a measurement of?

Not quite. Voltage is a measurement of potential difference. You don't measure voltage at a single point. You measure voltage across two points.

Potential energy as a general concept is a measurement of how much energy could be released if the subject were free move on its own. It is, in a sense, stored energy. You're familiar with gravitational potential energy. The other kinds are no different.

Why is cross-sectional area used to compare with resistivity in R = pL / A? Is circumference ever used?

The cross-sectional area is used because not all wires have a circular cross-section. Obviously for a cylindrical conductor you could use R = pL / (pi*r²), but cross-sectional area is a more general concept.

Ohh, I understand the different now. If there's a comma then the last bit without the comma is what is being described. If there's no comma then all the words after the first word is one thing. Thank-you!

Oh, but that means if someone says "bright yellow sun" it technically(?) means a bright yellow-sun :/ ? What about a bright-yellow sun? Do I just use a dash?

Usually the distinction DOESN'T matter, because "(bright yellow) sun" and "bright (yellow sun)" are both valid parses of the sentence. If the distinction truly matters, then yes, you can use a hyphen (not a dash, they're technically different). Though usually if the distinction matters you just reword the sentence ("The sun was bright yellow as it crossed the sky" instead of "the bright yellow sun crossed the sky").

That said, "bright yellow" is a somewhat unusual case -- technically it ought to be "brightly yellow" if you're treating it as a modified adjective (because adjectives don't modify other adjectives), but instead it's actually a modified noun ("yellow" as a thing instead of a description) being used as an adjective.