Do you mean values of the resistors from R1 to R4?In Example (b), the values of the resistors R1-R4 must be known in order to determine the polarity of the voltage across resistor R5.
And sometimes it may be reasonable to assign a polarity that you know is going to end up wrong.Here are two examples where you cannot know the correct polarity of the voltage and current before analysis:
The polarity of the voltage across resistor R1 in Example (a) cannot be determined until the values of the voltages Vs1 and Vs2 are known.
In Example (b), the values of the resistors R1-R4 must be known in order to determine the polarity of the voltage across resistor R5.
In circuit analysis, one can select any polarity to begin. The correct polarity will be ascertained after analysis.
by Jake Hertz
by Aaron Carman
by Jake Hertz
by Aaron Carman