# Does the length of a wire affect its resistance?

Zoey
Hello,

I would think that it would, because if the wire is longer there is more of a chance of their being foreign objects interfering, which could cause resistance, right? Or no?

Mentor
2021 Award
Yes, the resistance is directly proportional to the length.

• Zoey
Zoey
Yes, the resistance is directly proportional to the length.
Thanks! Homework Helper
Gold Member
Just for info... The same applies to thermal resistance. The thicker the insulation the longer the path heat has to travel and hence the higher the thermal resistance.

• Zoey
Zoey
Just for info... The same applies to thermal resistance. The thicker the insulation the longer the path heat has to travel and hence the higher the thermal resistance.
Thank you, that is definitely handy to keep in mind pixel
Just for completeness, the equation for the resistance of a wire is R = ρL/A where

ρ = the resistivity
L = the length
A = the cross sectional area

• Zoey
Zoey
Just for completeness, the equation for the resistance of a wire is R = ρL/A where

ρ = the resistivity
L = the length
A = the cross sectional area

Thanks! A formula is definitely something handy to have on hand Chris1983
No conductor is perfect (yet). The more material that current must pass through, the more resistance.

External factors that increase resistance or impedance are ambient temperature, power quality issues (harmonics, reflected sine waves, phase imbalance), and other electrical conductors and devices. All of these can cause excessive heat.

Generally conductors are run according to a plan, so a longer run is no more likely to encounter external problems than a shorter run if they are both run according to the same plan.

Impedance has nothing to do with the question/topic of this thread 