---
title: "Two small charged particles with charges \\(+Q\\) and \\(+4Q\\) are separated by a distance \\(L\\) along a line. A third particle with charge \\(q\\) is placed along the line between them such that the entire system of three particles remains at rest in electrostatic equilibrium with no external forces applied. What is the charge \\(q\\) of the third particle?"
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url: "https://nerd-notes.com/ubq/124560/"
date_modified: "2026-09-28T14:08:38+00:00"
---

# Two small charged particles with charges \(+Q\) and \(+4Q\) are separated by a distance \(L\) along a line. A third particle with charge \(q\) is placed along the line between them such that the entire system of three particles remains at rest in electrostatic equilibrium with no external forces applied. What is the charge \(q\) of the third particle?

Two small charged particles with charges \(+Q\) and \(+4Q\) are separated by a distance \(L\) along a line. A third particle with charge \(q\) is placed along the line between them such that the entire system of three particles remains at rest in electrostatic equilibrium with no external forces applied. What is the charge \(q\) of the third particle?

![A horizontal dashed line represents the line along which three particles lie. On the far left of the line is a small solid black circle labeled +Q. On the far right is another small solid black circle labeled +4Q. A horizontal dimension line with arrows at both ends spans between the center of the particle labeled +Q and the center of the particle labeled +4Q, with the dimension labeled L. Between the two outer particles, a third small solid black circle is located on the dashed line and labeled q. No other labels, lines, text, or axes appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1790604517-NSwOF4.jpg)

- **A.** \(-\dfrac{4}{9}Q\)
- **B.** \(-\dfrac{2}{9}Q\)
- **C.** \(+\dfrac{2}{9}Q\)
- **D.** \(+\dfrac{4}{9}Q\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/124560/*