---
title: "A long, straight wire lies along the x-axis and carries a constant current \\(I\\) in the positive x-direction. An electron is located on the positive y-axis at a distance \\(d\\) above the wire and is moving with speed \\(v\\) in the positive x-direction.  | Choice | Direction of magnetic field \\(\\vec{B}\\) | Direction of magnetic force \\(\\vec{F}_B\\) | | :— | :— | :— | | (A) | Into the page | Toward the wire (\\(-y\\)-direction) | | (B) | Into the page | Away from the wire (\\(+y\\)-direction) | | (C) | Out of the page | Away from the wire (\\(+y\\)-direction) | | (D) | Out of the page | Toward the wire (\\(-y\\)-direction) |  Which row in the table correctly indicates the direction of the magnetic field produced by the wire at the electron’s position and the direction of the magnetic force exerted on the electron?"
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url: "https://nerd-notes.com/ubq/118501/"
date_modified: "2026-08-04T08:11:06+00:00"
---

# A long, straight wire lies along the x-axis and carries a constant current \(I\) in the positive x-direction. An electron is located on the positive y-axis at a distance \(d\) above the wire and is moving with speed \(v\) in the positive x-direction.

| Choice | Direction of magnetic field \(\vec{B}\) | Direction of magnetic force \(\vec{F}_B\) |
| :— | :— | :— |
| (A) | Into the page | Toward the wire (\(-y\)-direction) |
| (B) | Into the page | Away from the wire (\(+y\)-direction) |
| (C) | Out of the page | Away from the wire (\(+y\)-direction) |
| (D) | Out of the page | Toward the wire (\(-y\)-direction) |

Which row in the table correctly indicates the direction of the magnetic field produced by the wire at the electron’s position and the direction of the magnetic force exerted on the electron?

A long, straight wire lies along the x-axis and carries a constant current \(I\) in the positive x-direction. An electron is located on the positive y-axis at a distance \(d\) above the wire and is moving with speed \(v\) in the positive x-direction.

| Choice | Direction of magnetic field \(\vec{B}\) | Direction of magnetic force \(\vec{F}_B\) |
| :--- | :--- | :--- |
| (A) | Into the page | Toward the wire (\(-y\)-direction) |
| (B) | Into the page | Away from the wire (\(+y\)-direction) |
| (C) | Out of the page | Away from the wire (\(+y\)-direction) |
| (D) | Out of the page | Toward the wire (\(-y\)-direction) |

Which row in the table correctly indicates the direction of the magnetic field produced by the wire at the electron's position and the direction of the magnetic force exerted on the electron?

![A horizontal black line represents a long straight wire extending left to right, with a rightward arrow labeled I directly below it. A distance d directly above the middle of the wire, a small circle containing a minus sign represents an electron labeled e^-. A horizontal vector arrow labeled v starts at the electron and points to the right. A coordinate axis indicator in the lower corner shows the positive x-axis pointing to the right and the positive y-axis pointing upward. No other labels, lines, text, or axes appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1785831065-wErY58.jpg)

- **A.** Field: Into the page; Force: Toward the wire (\(-y\)-direction)
- **B.** Field: Into the page; Force: Away from the wire (\(+y\)-direction)
- **C.** Field: Out of the page; Force: Away from the wire (\(+y\)-direction)
- **D.** Field: Out of the page; Force: Toward the wire (\(-y\)-direction)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/118501/*