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 ? (They are in a series)
Use R ρ*L/A For copper R 1.72x10^-8*0.370/(π*0.0120^2) 1.41x10^-5 Ω For Al R 2.63x10^-8*0.195/(π*0.0120^2) 1.13x10^-5 Ω Therefore total R 1.13x10^-5 + 1.41x10^-5 2.54x10^-5Ω
How about if you look it up in your textbook .lazy dude?
