---
title: "Three point charges are held fixed in a line: Charge 1 has charge \\(+2q\\), Charge 2 has charge \\(-q\\), and Charge 3 has charge \\(+q\\). A closed surface \\(S\\) encloses Charge 1 and Charge 2, but leaves Charge 3 outside.  Which choice correctly pairs the net electric flux \\(\\Phi_E\\) through surface \\(S\\) with the net flow of electric field lines across surface \\(S\\)?"
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url: "https://nerd-notes.com/ubq/117920/"
date_modified: "2026-08-04T08:02:35+00:00"
---

# Three point charges are held fixed in a line: Charge 1 has charge \(+2q\), Charge 2 has charge \(-q\), and Charge 3 has charge \(+q\). A closed surface \(S\) encloses Charge 1 and Charge 2, but leaves Charge 3 outside.

Which choice correctly pairs the net electric flux \(\Phi_E\) through surface \(S\) with the net flow of electric field lines across surface \(S\)?

Three point charges are held fixed in a line: Charge 1 has charge \(+2q\), Charge 2 has charge \(-q\), and Charge 3 has charge \(+q\). A closed surface \(S\) encloses Charge 1 and Charge 2, but leaves Charge 3 outside.

Which choice correctly pairs the net electric flux \(\Phi_E\) through surface \(S\) with the net flow of electric field lines across surface \(S\)?

![A horizontal layout showing three point charges in a line. On the left is a small filled circle labeled q_1 = +2q. In the middle, separated by a short horizontal distance, is a small filled circle labeled q_2 = -q. On the right is a small filled circle labeled q_3 = +q. A dashed oval contour labeled Surface S encloses q_1 and q_2 completely, but leaves q_3 outside on the right. No other lines, arrows, or text appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1785830554-aZ3KiA.jpg)

- **A.** \(\Phi_E = -\dfrac{q}{\varepsilon_0}\) ; Net inward flow of field lines
- **B.** \(\Phi_E = +\dfrac{q}{\varepsilon_0}\) ; Net outward flow of field lines
- **C.** \(\Phi_E = +\dfrac{2q}{\varepsilon_0}\) ; Net outward flow of field lines
- **D.** \(\Phi_E = 0\) ; Equal inward and outward flow of field lines

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/117920/*