circuit analysiscircuit-designresistance
Can somebody explain to me how to calculate the total resistance of the circuit in the picture?
I do not understand how to deal with the potentiometer and the red line. Does the current flow over \$R_{2.1}\$, bypassing \$R_{2.2}\$ and going on to \$R_3\$ and \$R_{\text{B}}\$? So would it be \$R_{\text{total}} = R_{2.1} + (R_{\text{B}} \parallel R_3)\$?
the book is pretty correct as the circuit is like this:
simulate this circuit – Schematic created using CircuitLab This circuit would be in series if there were no wires shorting the circuit and then net resistance would be 15 ohm.
I think you can try Y-Δ transform, transform half of the upside or downside 3 resistors to "Y", then it'll be easier to analyze.
Best Answer
Assuming you want the resistance at the two wires, yes, R2.2 is shorted out (in parallel with zero). It's completely bypassed.
Therefore total resistance (when switch is closed) is:
Rt = R2.1 + R3//RB [ // symbol for 'in parallel'] Rt = R2.1 + (R3*RB/(R3+RB))
If you want the resistance across UB, then just ignore R2.1 and work out R3//RB.