Physics

Problem

## SECTION D - Capacitance ![](https://storage.googleapis.com/diraq-contents/question-bank/question-images/c30d968f6c8d/2025_11_20_9d1bbfa4e2392a3466a4g-52.jpg) 1978E3. A capacitor is composed of two concentric spherical shells of radii

a

and

b

, respectively, that have equal and opposite charges as shown above. Just outside the surface of the inner shell, the electric field is directed radially outward and has magnitude

\mathrm{E}_{0}

. a. With the use of Gauss's law, express the charge +Q on the inner shell as a function of

\mathrm{E}_{\mathrm{o}}

and a. b. Write an expression for the electric field strength E between the shells as a function of

\mathrm{E}_{\mathrm{o}}

, a , and r . c. What is the potential difference V between the shells as a function of

\mathrm{E}_{\mathrm{o}}, \mathrm{a}

, and b ? d. Express the energy U stored in this capacitor as a function of

\mathrm{E}_{\mathrm{o}}

, a, and b. e. Determine the value of a that should be chosen in order to maximize U , if

\mathrm{E}_{\mathrm{o}}

and b are fixed.

Browse the problem library