1. The problem statement, all variables and given/known data If the magnitude of the drift velocity of free electrons in a copper wire is 7.84×10-4 m/s, what is the electric field in the conductor? (Also gives chart that states that the resistivity of Cu is 1.7×10-8 Ωm) 2. Relevant equations vd=(qEτ)/me (where τ is avg. time between collisions) ρ=1/σ=me/(nq2τ) 3. The attempt at a solution first I solved for τ in the second equation: τ=me/(nq2ρ) Then I put this value in for τ in the first equation: vd=(qE(me/(nq2ρ))/me Simplify: vd=E/(qnp) When I put in values: 7.84×10-4=E/(1.6×10-19)(1.7×10-8)(n) I didn't know how to get n (number of e- per m3), so I googled the density of copper (8.96 g/ml) and did some conversions to get n=8.475×1028, which gave me a correct answer of E=.18V/m, but I don't think I was supposed to use google, and no density chart is given in the book. Is there another way to do this that I overlooked?