Two cylindrical bars, each with diameter of 2 cm, are welded together end to end. One of the original bars is copper and is 0.31m long. The other bar is platinum and is 0.175m long. What is the resistance between the ends of the welded bar at 20 degrees C?
Look up the volume resistivities ρ of Cu and Pt. For each bar, R ρL/A, where L is length and A is cross-section area. For this series-connected setup, R(total) is the sum of the two R values.
