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Let's say I am trying to calculate and measure the resistance of a wire that I know the cross-sectional Area and length. Does the excess part as seen in the image effect the length? And should it be taken in to consideration when doing the calculations? Or because there is no current passing through, can it be omitted? This is a noob question I know, but i need to be sure.

schematic

simulate this circuit – Schematic created using CircuitLab

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    \$\begingroup\$ No, it plays no part in the circuit. I was tempted into sarcasm but fought the urge. \$\endgroup\$ – Finbarr Feb 23 '18 at 22:55
  • \$\begingroup\$ It will if it touches something else like the chassis... \$\endgroup\$ – Solar Mike Feb 23 '18 at 22:56
  • \$\begingroup\$ All wire has resistance. Even the unused part. The only significance to a IR drop in voltage. \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Feb 23 '18 at 23:00
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    \$\begingroup\$ As pictured, no. But if you have current flowing in the completed part of the circuit at radio frequencies (rather than DC as depicted) and the stub has a length that is a meaningful fraction of a wavelength, then it may start to behave as an antenna, and the resistance of an antenna theoretically matters. Additionally, adding an antenna does alter the behavior of the rest of the circuit. \$\endgroup\$ – Chris Stratton Feb 23 '18 at 23:02
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    \$\begingroup\$ I'd worry about the loop being a short circuit with infinite current from an ideal source and wire. \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Feb 24 '18 at 0:42
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It has no effect on resistance calculation.
However, depending on the circuit, an "unused" piece of wire can have effects, as it could function as an antenna.

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    \$\begingroup\$ yes, or as a heatsink. \$\endgroup\$ – Jasen Feb 24 '18 at 0:07

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