PsySc0rpi0n
- Joined Mar 4, 2014
- 1,755
The voltage source value is positive or negative depending on the way we measure it, I guess. If I place the black probe of a multmeter in the minus side and the red probe at the plus sign, it will read +15V, if I measure it the other way around, it will read -15V.But it isn't. The voltage across the right voltage source is +15 V while the voltage at the top right node (of your schematic with the components swapped) is -15 V due to the orientation of the supply.
I don't know what you mean by wanting to find another "mnemonic" to perform the analysis. If you mean finding better labels, that's a simple matter of just choosing different labels for things that are different (regardless of whether they might numerically have the same value). In this case, call the two voltage sources Vs1 and Vs2 and call the node voltages V1, V2, etc. (or Va, Vb, etc.).
About the mnemonic for nodal analysis, I mean the mnemonic that I use to perform nodal analysis which is:
voltage at the required node minus voltage of branch 'n' over the impedance of branch 'n' equals the voltage at required node minus the voltage of branch 'n + 1' over the impedance of branch 'n + 1' and so on, having in mind the directions of currents I chose.
I say the same... The value of the voltage of the voltage source depends on the way we measure it! At least is this way I think! Anyway, I got the point!The source voltage is the voltage difference between the voltage at the labeled + terminal and the voltage at the labeled - terminal, i.e. V+ minus V-. The voltage of a node is the absolute voltage of a point in the circuit with respect to your chosen reference point, usually a common return or ground. As Bahn said, clearly and separately labeling sources and nodes will reduce confusion and the possibility of conflating the two.