Walker, Halliday & Resnick — Current and Resistance: Problem 10

10 Figure 26-18 shows wire section 1 of diameter \(D_1 = 4.00R\) and wire section 2 of diameter \(D_2 = 1.75R\), connected by a tapered section. The wire is copper and carries a current. Assume that the current is uniformly distributed across any cross-sectional area through the wire's width. The electric potential change \(V\) along the length \(L = 2.00 \text{ m}\) shown in section 2 is \(10.0 \text{ μV}\). The number of charge carriers per unit volume is \(8.49 \times 10^{28} \text{ m}^{-3}\). What is the drift speed of the conduction electrons in section 1?