On the electric field at the surface of a uniformly-charged cylindrical shell

In some recent papers, I have shown that the electric field at the surface of a uniformly-charged spherical shell (or a conducting sphere, since the charge distribution is the same) evaluates to half the field discontinuity across its surface. For a cylindrical shell, however, only a simple applicat...

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Main Author: Fábio M.S. Lima
Format: Article
Language:Portuguese
Published: Sociedade Brasileira de Física 2025-01-01
Series:Revista Brasileira de Ensino de Física
Subjects:
Online Access:http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1806-11172025000100901&lng=en&tlng=en
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author Fábio M.S. Lima
author_facet Fábio M.S. Lima
author_sort Fábio M.S. Lima
collection DOAJ
description In some recent papers, I have shown that the electric field at the surface of a uniformly-charged spherical shell (or a conducting sphere, since the charge distribution is the same) evaluates to half the field discontinuity across its surface. For a cylindrical shell, however, only a simple application of Gauss’s law for infinitely long shells is found in textbooks, which yields a field that is null inside the shell and, outside it, decays with the inverse of the distance to the central axis. Nothing is said for points located exactly at the shell. For those points, the amount of charge surrounded by a Gaussian surface coinciding with the shell is undefined, which makes the application of Gauss’s law inconclusive. In this note, by treating a cylindrical shell as a collection of identical charged rings, I derive that electric field in terms of elliptic integrals and then I show that, for very long shells, it reduces to half the field discontinuity across the shell.
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issn 1806-9126
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publisher Sociedade Brasileira de Física
record_format Article
series Revista Brasileira de Ensino de Física
spelling doaj-art-1154102870554b84999c7fbcf1ad89232025-01-21T07:35:48ZporSociedade Brasileira de FísicaRevista Brasileira de Ensino de Física1806-91262025-01-014710.1590/1806-9126-rbef-2024-0312On the electric field at the surface of a uniformly-charged cylindrical shellFábio M.S. Limahttps://orcid.org/0000-0001-5884-6621In some recent papers, I have shown that the electric field at the surface of a uniformly-charged spherical shell (or a conducting sphere, since the charge distribution is the same) evaluates to half the field discontinuity across its surface. For a cylindrical shell, however, only a simple application of Gauss’s law for infinitely long shells is found in textbooks, which yields a field that is null inside the shell and, outside it, decays with the inverse of the distance to the central axis. Nothing is said for points located exactly at the shell. For those points, the amount of charge surrounded by a Gaussian surface coinciding with the shell is undefined, which makes the application of Gauss’s law inconclusive. In this note, by treating a cylindrical shell as a collection of identical charged rings, I derive that electric field in terms of elliptic integrals and then I show that, for very long shells, it reduces to half the field discontinuity across the shell.http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1806-11172025000100901&lng=en&tlng=enElectric fieldsGauss’s lawCylindrical shell
spellingShingle Fábio M.S. Lima
On the electric field at the surface of a uniformly-charged cylindrical shell
Revista Brasileira de Ensino de Física
Electric fields
Gauss’s law
Cylindrical shell
title On the electric field at the surface of a uniformly-charged cylindrical shell
title_full On the electric field at the surface of a uniformly-charged cylindrical shell
title_fullStr On the electric field at the surface of a uniformly-charged cylindrical shell
title_full_unstemmed On the electric field at the surface of a uniformly-charged cylindrical shell
title_short On the electric field at the surface of a uniformly-charged cylindrical shell
title_sort on the electric field at the surface of a uniformly charged cylindrical shell
topic Electric fields
Gauss’s law
Cylindrical shell
url http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1806-11172025000100901&lng=en&tlng=en
work_keys_str_mv AT fabiomslima ontheelectricfieldatthesurfaceofauniformlychargedcylindricalshell