What is the resistance between the ends of the welded bar at 20 oC ask?
Two cylindrical bars, each with diameter of 2.40 cm, are welded together end-to-end. One of the original bars is copper and is 0.370 m long. The other bar is aluminum and is 0.195 m long. What is the resistance between the ends of the welded bar at 20 oC ?
Resistance of a wire in Ω
R = ρL/A
ρ is resistivity of the material in Ω-m
L is length in meters
A is cross-sectional area in m²
A = πr², r is radius of wire in m
resistivity Cu 17.2e-9 Ω-m
resistivity Al 28.2e-9 Ω-m
Calculate the resistance of each section and add them (assuming they are in series, "end to end" is a bit vague)
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