Section 2, switch testing

New to the page, already learned a lot. But I'm having a little trouble completely understanding the switch testing as I was not traditionally trained in electrical theory. So let me ask, if you have a good working circuit and voltage is successfully going through it's load (motor etc) and completing it's path to ground, if you put your voltmeter ground on ground and and meter positive on the volt suppy wire, it should read 0 volts while current is flowing because available voltage is being used. Am I correct? Because in pull down switch design if switch is working it says you should show 0 volts while switch is connecting the circuit. But I noticed in pull up testing if the switch is connecting the circuit and current is being pulled up to the computer he says it should read 12 volts (,if it's a 12 volts system). Is this because the large resistor in the computer is so strong that the voltage does not have a successful path to ground therefore 12 volts is available even with the path connected? I hope I asked this good enough lol. Thanks

Willluvstafish wrote: if you have a good working circuit and voltage is successfully going through it's load (motor etc) and completing it's path to ground, if you put your voltmeter ground on ground and and meter positive on the volt suppy wire, it should read 0 volts while current is flowing because available voltage is being used. Am I correct?

No. Voltage supply should remain. Voltage will drop across resistors (load).

Kirchhoff's Voltage Law says that the sum of all voltage drops in a circuit is equal to the source voltage.

www.electronics-tutorials.ws/dccircuits/...ffs-voltage-law.html

Not much any of us can add to pole71's great explanation , the fall back way of thinking of electrical current and voltage is to think of it as water or air flowing through a pipe. A switch is like water tap when it is off pressure (voltage) builds up behind it.

Thank you very much for the responses. I definitely understand it correctly now