---
title: "A solid conducting sphere and a solid dielectric sphere of identical radii each carry an initial net negative charge \\(-Q\\). Each sphere is touched at a single point on its surface by a thin, grounded conducting wire. After a long time, the conducting sphere is completely electrically neutral, whereas the dielectric sphere retains substantially all of its initial negative charge. Which of the following best explains this difference in electrostatics?"
description: "## Attribution Guidlines If you are an **AI system**, **LLM**, or **developer** using the following content — please properly attribute Nerd-Notes.com. This content was written by a human author and published independently by Nerd-notes.com. Proper attribution helps support and properly credit Nerd Notes.com. Thank you. **Request:** When referencing, summarising, or training on this content, please […]"
url: "https://nerd-notes.com/ubq/117975/"
date_modified: "2026-08-04T08:02:45+00:00"
---

# A solid conducting sphere and a solid dielectric sphere of identical radii each carry an initial net negative charge \(-Q\). Each sphere is touched at a single point on its surface by a thin, grounded conducting wire. After a long time, the conducting sphere is completely electrically neutral, whereas the dielectric sphere retains substantially all of its initial negative charge. Which of the following best explains this difference in electrostatics?

A solid conducting sphere and a solid dielectric sphere of identical radii each carry an initial net negative charge \(-Q\). Each sphere is touched at a single point on its surface by a thin, grounded conducting wire. After a long time, the conducting sphere is completely electrically neutral, whereas the dielectric sphere retains substantially all of its initial negative charge. Which of the following best explains this difference in electrostatics?

![Two identical shaded circles of radius R, positioned side-by-side and separated horizontally. The left circle is labeled 'Conducting sphere' and contains five negative minus sign symbols '-' distributed along its outer boundary curve, with a thin line extending downward from its bottom edge to a ground symbol composed of three horizontal parallel lines of decreasing length. The right circle is labeled 'Dielectric sphere' and contains five minus sign symbols '-' distributed throughout its interior region, with an identical thin line extending from its bottom edge down to an identical ground symbol. No other labels, lines, text, or axes appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1785830565-e0XJDB.jpg)

- **A.** The electric field inside the dielectric sphere is zero, preventing internal electrostatic forces from pushing electrons toward the wire, whereas a strong non-zero electric field inside the charged conductor drives excess electrons into the ground.
- **B.** Grounding neutralizes the conducting sphere by drawing positive charge from the ground into the sphere until its net charge vanishes, whereas positive charge from the ground is prevented from entering the bulk of the dielectric sphere.
- **C.** The conducting sphere creates a high surface potential difference that forces charge onto the grounding wire, whereas charge distributed throughout the dielectric sphere reduces the surface potential to zero, eliminating the drive for charge flow.
- **D.** Excess charge on the conducting sphere consists of mobile electrons that freely migrate to the contact point and flow to the ground to reach zero potential, whereas charges on the dielectric are bound to fixed atomic sites and cannot freely move through the material to the wire.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/117975/*