---
title: "An uncharged, isolated spherical conducting shell of inner radius \\(a\\) and outer radius \\(b\\) surrounds a cavity containing a single point charge \\(+q\\) initially at the geometric center. An experimenter moves the point charge to an off-center location within the cavity without allowing it to touch the inner conducting wall. Which of the following correctly describes and explains the effect of this displacement on the electric field in the region \\(r > b\\) outside the shell?"
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url: "https://nerd-notes.com/ubq/121161/"
date_modified: "2026-08-23T04:58:20+00:00"
---

# An uncharged, isolated spherical conducting shell of inner radius \(a\) and outer radius \(b\) surrounds a cavity containing a single point charge \(+q\) initially at the geometric center. An experimenter moves the point charge to an off-center location within the cavity without allowing it to touch the inner conducting wall. Which of the following correctly describes and explains the effect of this displacement on the electric field in the region \(r > b\) outside the shell?

An uncharged, isolated spherical conducting shell of inner radius \(a\) and outer radius \(b\) surrounds a cavity containing a single point charge \(+q\) initially at the geometric center. An experimenter moves the point charge to an off-center location within the cavity without allowing it to touch the inner conducting wall. Which of the following correctly describes and explains the effect of this displacement on the electric field in the region \(r > b\) outside the shell?

![A two-dimensional cross-sectional diagram of a thick spherical shell. The outer boundary is a solid black circle of radius b centered at the origin. The inner boundary is a concentric solid black circle of radius a centered at the origin. The region between radius a and radius b has a light gray solid fill representing the conducting shell material. The hollow circular region inside radius a has a white fill. A small black dot labeled +q is positioned horizontally to the right of the center within the white cavity. A dashed line extends radially from the center to the outer boundary labeled b, and a solid arrow extends radially from the center to the inner boundary labeled a. No other labels, lines, text, or axes appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1787461100-zrSo43.jpg)

- **A.** The exterior electric field becomes stronger on the side nearest the displaced charge because the direct Coulomb field from the closer source charge is not entirely canceled by the inner wall.
- **B.** The exterior electric field remains unchanged and spherically symmetric because the interior conductor maintains \(\vec{E} = 0\), isolating the outer surface and allowing its charge to stay uniformly distributed.
- **C.** The exterior electric field becomes asymmetric because the positive surface charge on the outer boundary redistributes to mirror the localized negative charge on the cavity wall.
- **D.** The exterior electric field drops to zero everywhere because the displaced charge polarizes the neutral shell such that all exterior electrostatic flux is completely contained.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/121161/*