Concept explainers
The resistance values in Table 2.4 are calibrated for operation at 20°C. They may be corrected for operation at other temperatures using the relationship6
where T1 = reference temperature (20°C in present case)
T2 = desired operating temperature
R1 = resistance at T1
R2 = resistance at T2
A piece of equipment relies on an external wire made of 28 AWG soft copper, which has a resistance of 50.0 Ω at 20°C. Unfortunately, the operating environment has changed, and it is now 110.5°F. (a) Calculate the length of the original wire. (b) Determine by how much the wire should be shortened so that it is once again 50.0 Ω.
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