Effect of the internal temperature of a conductor on the accuracy of determining its electrical resistance

Conclusions

• 1. When the resistance of homogeneous cylindrical conductors of 6.5 mm diameter for copper and 3.3 mm for manganin are determined at a current density of 1.5 amp/mm², the error of measurement due to temperature differences inside the conductor and at its surface can be ignored owing to their small values.

• 2. When the resistance of cylindrical conductors with diameters greater than 6.5 cm for copper and 3.3 cm for manganin are determined, the errors due to the above-mentioned cause must be corrected according to formula (27).

• 3. Formula (27) holds for sufficiently long homogeneous cylindrical conductors with a temperature coefficient whose sum of higher-power terms is not larger than the first term.