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This is a circuit that I have on a problem set. enter image description here

I believe that, starting from a, the diagonal resistor is in parallel with the leftmost resistor. From there, the equivalent resistance is in series with the bottom resistor, and this whole equivalent is in parallel with the rightmost resistor, giving me a resistance of 12kOhm, however a classmate found it to be 8kOhm.

Can someone help me determine the correct resistance?

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  • \$\begingroup\$ Hello and welcome. You'll find that labelling your diagram (R1 etc) might really help. Alternatively, try drawing what your text describes and comparing with the original. Another thing to try is use the simulator here on EE.SE, which will show you which is right, and then you can try to work out why. \$\endgroup\$
    – jonathanjo
    Jul 17, 2023 at 20:28

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Your approach is correct; here is the circuit redrawn as you have described it.

schematic

simulate this circuit – Schematic created using CircuitLab

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  • \$\begingroup\$ Thank you - my TA is gonna get it haha \$\endgroup\$
    – big_yoshi
    Jul 17, 2023 at 20:38
  • \$\begingroup\$ 8k Ohm; is the value from top right to bottom left. \$\endgroup\$
    – jonathanjo
    Jul 17, 2023 at 20:40
  • \$\begingroup\$ So if b was placed at the bottom left, instead of where it is, then the value would be 8kOhm? \$\endgroup\$
    – big_yoshi
    Jul 17, 2023 at 20:48
  • \$\begingroup\$ @cole_prutzman indeed. You can see why the other person made that mistake. par(par(20,20), ser(20, 20)) = par(10, 40) = 1/(1/10 + 1/40) = 1/(4/40 + 1/40) = 1/(5/40) = 40/5 = 8. \$\endgroup\$
    – jonathanjo
    Jul 17, 2023 at 21:02

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