---
title: "Two long, parallel, solid cylindrical conductors are oriented perpendicular to the \\(xy\\)-plane. Conductor 1 has radius \\(R\\), is centered at \\((x, y) = (-3R, 0)\\), and carries a uniform current \\(I\\) directed out of the page. Conductor 2 has radius \\(2R\\), is centered at \\((x, y) = (+3R, 0)\\), and carries a uniform current \\(2I\\) directed into the page. Which of the following diagrams best represents the direction and relative magnitude of the net magnetic field \\(\\vec{B}\\) at points \\(P\\) at \\((-5R, 0)\\), \\(Q\\) at \\((0, 0)\\), and \\(R\\) at \\((+4R, 0)\\)?"
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url: "https://nerd-notes.com/ubq/124980/"
date_modified: "2026-09-28T14:12:30+00:00"
---

# Two long, parallel, solid cylindrical conductors are oriented perpendicular to the \(xy\)-plane. Conductor 1 has radius \(R\), is centered at \((x, y) = (-3R, 0)\), and carries a uniform current \(I\) directed out of the page. Conductor 2 has radius \(2R\), is centered at \((x, y) = (+3R, 0)\), and carries a uniform current \(2I\) directed into the page. Which of the following diagrams best represents the direction and relative magnitude of the net magnetic field \(\vec{B}\) at points \(P\) at \((-5R, 0)\), \(Q\) at \((0, 0)\), and \(R\) at \((+4R, 0)\)?

Two long, parallel, solid cylindrical conductors are oriented perpendicular to the \(xy\)-plane. Conductor 1 has radius \(R\), is centered at \((x, y) = (-3R, 0)\), and carries a uniform current \(I\) directed out of the page. Conductor 2 has radius \(2R\), is centered at \((x, y) = (+3R, 0)\), and carries a uniform current \(2I\) directed into the page. Which of the following diagrams best represents the direction and relative magnitude of the net magnetic field \(\vec{B}\) at points \(P\) at \((-5R, 0)\), \(Q\) at \((0, 0)\), and \(R\) at \((+4R, 0)\)?

![A horizontal axis labeled x passes through the origin marked with a small tick labeled 0. On the left, centered at -3R, is a circle of radius R with light gray fill containing a centered dot symbol labeled I. On the right, centered at +3R, is a circle of radius 2R with light gray fill containing a centered cross symbol labeled 2I. Three points on the horizontal line are marked with solid black dots: point P at -5R, point Q at 0, and point R at +4R located inside the larger circle. A small vertical segment at 0 represents the y-axis, labeled y. No other labels, lines, text, or axes appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1790604748-Moo6ao.jpg)

- **A.** Diagram A
- **B.** Diagram B
- **C.** Diagram C
- **D.** Diagram D

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/124980/*