---
title: "A cylindrical copper wire with radius \\(r_1\\) carries a steady current \\(I\\). A second cylindrical copper wire with radius \\(r_2 = 2r_1\\) carries the same current \\(I\\). If \\(v_{d,1}\\) and \\(v_{d,2}\\) are the average electron drift speeds in the first and second wires, respectively, what is the ratio \\(\\dfrac{v_{d,1}}{v_{d,2}}\\)?"
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url: "https://nerd-notes.com/ubq/121537/"
date_modified: "2026-08-23T05:23:47+00:00"
---

# A cylindrical copper wire with radius \(r_1\) carries a steady current \(I\). A second cylindrical copper wire with radius \(r_2 = 2r_1\) carries the same current \(I\). If \(v_{d,1}\) and \(v_{d,2}\) are the average electron drift speeds in the first and second wires, respectively, what is the ratio \(\dfrac{v_{d,1}}{v_{d,2}}\)?

A cylindrical copper wire with radius \(r_1\) carries a steady current \(I\). A second cylindrical copper wire with radius \(r_2 = 2r_1\) carries the same current \(I\). If \(v_{d,1}\) and \(v_{d,2}\) are the average electron drift speeds in the first and second wires, respectively, what is the ratio \(\dfrac{v_{d,1}}{v_{d,2}}\)?

- **A.** \(\dfrac{1}{4}\)
- **B.** \(\dfrac{1}{2}\)
- **C.** \(2\)
- **D.** \(4\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/121537/*