Quote:
Originally Posted by Chris K
I often hear them refer to a resistor "pulling the voltage down" or "pulling this to ground."
What does that mean exactly? I have always thought of resistors well, resisting the flow of voltage that passes through them and restricting the flow of electrons. Why would DC voltage choose to take a path through something that's resistant to flow instead of where it is intended to go? To my brain, it sounds like water being more apt to flow upstream over a dam than downstream. Does a 100K resistor pull voltage to ground more than a 1K resistor and, if so, why?
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Questions in order:
A resistor can divert current to ground, therefore lowering the voltage at a particular point. "Pulling Down" is normally a term used in digital electronics, thought the concept can be used in analog electronics also. The resistor allows current to pass to ground, therefore lowering the voltage at that point. The lower the resistance, the more it allows the current to flow and the lower the voltage becomes at that point with respect to ground. Keep lowering the resistor value, and you have a short which brings that point in the circuit to ground level.
More current will flow through the path of least resistance, ie the lower resistance. It doesn't mean that no current flows thru a higher resistance path at that particular point in the circuit (called a node), it just means less flows. And when you state that you think the current should flow to the intended place, well, that "place" just might have a higher resistance, therefore it has no incentive to flow there, lol, it is following the path of least resistance.
No, a 100k resistor to ground will not lower a point with respect to ground more than a 1k resistor. The 1k will allow much more current to flow, the current takes the path of least resistance. The current always wants to return to ground, or the most negative point in the circuit.