---
title: "A solid conducting sphere of radius \\(a\\) carrying an initial net charge of \\(+2Q\\) is positioned concentrically inside a thin spherical conducting shell of radius \\(b\\) (where \\(b > a\\)) carrying an initial net charge of \\(-Q\\). A thin conducting wire with an open switch connects the inner sphere to the shell. The switch is closed until electrostatic equilibrium is reached, and then reopened. Which of the following options correctly identifies the final net charge on the inner sphere and the final charge on the outer surface of the shell?"
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url: "https://nerd-notes.com/ubq/117934/"
date_modified: "2026-08-04T08:02:37+00:00"
---

# A solid conducting sphere of radius \(a\) carrying an initial net charge of \(+2Q\) is positioned concentrically inside a thin spherical conducting shell of radius \(b\) (where \(b > a\)) carrying an initial net charge of \(-Q\). A thin conducting wire with an open switch connects the inner sphere to the shell. The switch is closed until electrostatic equilibrium is reached, and then reopened. Which of the following options correctly identifies the final net charge on the inner sphere and the final charge on the outer surface of the shell?

A solid conducting sphere of radius \(a\) carrying an initial net charge of \(+2Q\) is positioned concentrically inside a thin spherical conducting shell of radius \(b\) (where \(b > a\)) carrying an initial net charge of \(-Q\). A thin conducting wire with an open switch connects the inner sphere to the shell. The switch is closed until electrostatic equilibrium is reached, and then reopened. Which of the following options correctly identifies the final net charge on the inner sphere and the final charge on the outer surface of the shell?

![A cross-sectional diagram showing a solid shaded inner circle of radius a labeled +2Q at its center. Concentric with this inner circle is a thin outer circular ring of radius b labeled -Q. A thin black line representing a wire extends from the outer surface of the inner circle to the inner edge of the outer ring, interrupted by a open switch symbol S. No other labels, lines, arrows, or text appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1785830557-pUup2w.jpg)

- **A.** Charge on inner sphere: \(+2Q\) | Charge on outer surface: \(-Q\)
- **B.** Charge on inner sphere: \(+\dfrac{1}{2}Q\) | Charge on outer surface: \(+\dfrac{1}{2}Q\)
- **C.** Charge on inner sphere: \(0\) | Charge on outer surface: \(+Q\)
- **D.** Charge on inner sphere: \(-Q\) | Charge on outer surface: \(+2Q\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/117934/*