---
title: "A point charge \\(q\\) is fixed on the central symmetry axis of a flat, circular disk of radius \\(R\\) at a perpendicular distance \\(d\\) from the center of the disk. Which of the following expressions represents the net electric flux through the disk?"
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url: "https://nerd-notes.com/ubq/117928/"
date_modified: "2026-08-04T08:02:36+00:00"
---

# A point charge \(q\) is fixed on the central symmetry axis of a flat, circular disk of radius \(R\) at a perpendicular distance \(d\) from the center of the disk. Which of the following expressions represents the net electric flux through the disk?

A point charge \(q\) is fixed on the central symmetry axis of a flat, circular disk of radius \(R\) at a perpendicular distance \(d\) from the center of the disk. Which of the following expressions represents the net electric flux through the disk?

![A flat ellipse viewed at a 3D perspective tilt represents a circular disk of radius R lying in a horizontal plane. A vertical dashed central axis line passes perpendicularly through the center of the disk. A single point charge labeled q is positioned on this vertical axis at a perpendicular distance d directly above the center of the disk. A radial arrow labeled R extends from the center of the disk to its right edge. A vertical arrow labeled d extends along the central axis from the center of the disk up to the point charge q. No other labels, lines, text, or axes appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1785830556-ryD0DP.jpg)

- **A.** \(\dfrac{q}{2\varepsilon_0}\left(\dfrac{d}{\sqrt{R^2 + d^2}}\right)\)
- **B.** \(\dfrac{q}{2\varepsilon_0}\left(1 - \dfrac{d}{\sqrt{R^2 + d^2}}\right)\)
- **C.** \(\dfrac{q}{4\pi\varepsilon_0}\left(\dfrac{R^2}{R^2 + d^2}\right)\)
- **D.** \(\dfrac{q}{\varepsilon_0}\left(1 - \dfrac{d}{R + d}\right)\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/117928/*