3
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The book (Principles of Electric Circuits by Thomas Floyd 9th edition, International edition) says it's 1.955k Ω.
When I calculate I get (R1 || R2) + (R3 || R4) + R5 = 3.38k Ω.

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    \$\begingroup\$ Between which two points? \$\endgroup\$ – stevenvh Sep 25 '12 at 14:53
  • \$\begingroup\$ What reasoning did you use when you decided to place R3 and R4 in parallel? Also why R5 in series, if R1 and R2 are in parallel? \$\endgroup\$ – AndrejaKo Sep 25 '12 at 14:55
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    \$\begingroup\$ These kinds of problems are fairly easy to attack by reducing parts of the circuit successively to Thevenin equivalents. If you only care about the resistance, not the voltage, then you can consider all voltage sources as shorts to make things even simpler. To walk thru a solution, we need to know which two nodes you are trying to find the effective total resistance between, as Steven already mentioned above. \$\endgroup\$ – Olin Lathrop Sep 25 '12 at 15:09
6
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I assume the total resistance is requested from the + output of the 2V supply to GND. That gives:

(((R4 || R5) + R3) || R2) + R1 = 1.95498k

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    \$\begingroup\$ Actually, that works for either supply. If you swap the two right-hand arms of the circuit, you'll see the symmetry. \$\endgroup\$ – Dave Tweed Sep 25 '12 at 15:41
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    \$\begingroup\$ Thank you so much! I can't believe what I was thinking... did tons of exercises like these, then suddenly today I just... went full retard... \$\endgroup\$ – IQlessThan70 Sep 25 '12 at 19:55
  • \$\begingroup\$ @IQlessThan70 - Well, with an RTIQ (Room Temperature IQ) you can't help it, I guess... :-) \$\endgroup\$ – stevenvh Sep 27 '12 at 15:47
  • \$\begingroup\$ I'm surprised Steven didn't make a remark on the 6 significant digits... :) \$\endgroup\$ – Johan.A Dec 13 '13 at 13:33

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