It means that the point (i.e., node) labelled + is [to be] regarded as being at a voltage more positive than is the one labelled -LongApple said:Labeling + or - on random point on circuit- What does it mean in this link?
CWatters said:I believe the + and - signs your first and second circuits are trying to convey different things.
In the first circuit it looks like the +ve and -ve terminals are the +ve and -ve terminals of a battery or similar voltage source. I say this because both the 30V battery and the 25 Ohm resistor are between the +ve and -ve symbols. It appear they are trying to say that the 25 ohm resistor is an internal resistance.
Inthe secondboth circuits the +ve and -ve symbols near resistors are to define the direction of the corresponding voltage drop across the resistor (eg what BvU said).
The basic procedure to follow when solving circuits like this is to first mark up the circuit with either +ve and -ve symbols like this or use arrows to indicate which end of any voltage you define to be +ve. It doesn't matter if you are wrong. The important thing is to be consistent when you convert your definitions into circuit equations (eg KCL, KVL).
So for example take a look at the 6R resistor on the right. For whatever reason the person that labelled the circuit choose to define V3 such that the bottom end is +ve. Now if you solve the circuit equations and find V3 turns out to be a positive number then the bottom end of the 6R resistor will indeed be +ve with respect to the top end. However if V3 turns out to be a negative number that means the top end of the 6R resistor will be +ve with respect to the bottom end. Neither is "wrong" although one appears slightly odd.
I suggest you work out V3 as an exercise.
The labeling of + or - on a random point on a circuit is to indicate the polarity of the voltage or current at that point. This helps to identify the direction of flow and can assist in troubleshooting and circuit analysis.
The + and - labels on a circuit are typically assigned based on the direction of current flow. The point where current enters the circuit is labeled + and the point where it exits is labeled -. This is known as the conventional current flow direction.
There are no universally accepted standards for labeling + or - on a circuit. However, the most common convention is to label the positive end of a voltage source as + and the negative end as -. This convention is also used for labeling the terminals of resistors and other circuit components.
No, + and - labels cannot be interchanged on a circuit. The labels are assigned based on the direction of current flow and switching them would result in incorrect analysis of the circuit.
No, not all circuits require + and - labels. Simple circuits with only one source of current or voltage may not require labeling. However, for more complex circuits with multiple sources, labeling + and - can be helpful in understanding the circuit's behavior.