---
title: "A thin, straight rod of length \\(L\\) carries a net positive charge \\(Q\\) distributed uniformly along its length. An observation point \\(P\\) is located at a distance \\(r\\) from the center of the rod such that \\(r \\gg L\\). Which of the following expressions best approximates the magnitude of the electric field at point \\(P\\)?"
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url: "https://nerd-notes.com/ubq/117941/"
date_modified: "2026-08-04T08:02:38+00:00"
---

# A thin, straight rod of length \(L\) carries a net positive charge \(Q\) distributed uniformly along its length. An observation point \(P\) is located at a distance \(r\) from the center of the rod such that \(r \gg L\). Which of the following expressions best approximates the magnitude of the electric field at point \(P\)?

A thin, straight rod of length \(L\) carries a net positive charge \(Q\) distributed uniformly along its length. An observation point \(P\) is located at a distance \(r\) from the center of the rod such that \(r \gg L\). Which of the following expressions best approximates the magnitude of the electric field at point \(P\)?

![A horizontal thin rod of length L is centered on the origin. The rod is labeled with total charge Q and length L. A point labeled P is positioned at a distance r to the right of the center of the rod along its central horizontal axis. A dashed line indicates the distance r from the center of the rod to point P. No other labels, lines, text, or axes appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1785830558-57wgSL.jpg)

- **A.** \(\dfrac{1}{4\pi\varepsilon_0}\dfrac{Q}{r^2}\)
- **B.** \(\dfrac{1}{2\pi\varepsilon_0}\dfrac{Q}{r L}\)
- **C.** \(\dfrac{1}{4\pi\varepsilon_0}\dfrac{Q L}{r^3}\)
- **D.** \(\dfrac{1}{2\pi\varepsilon_0}\dfrac{Q}{r^2}\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/117941/*