Electric Field Equation Hollow Cylinder

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Discussion Overview

The discussion revolves around the electric field equation for a hollow cylinder shell of finite length, specifically focusing on the conditions under which it can be calculated and the challenges involved. The scope includes theoretical considerations and mathematical reasoning related to electric fields in different configurations of cylindrical charge distributions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant inquires about an equation for the electric field inside a hollow cylinder shell of finite length.
  • Another participant suggests that a closed formula may not exist for all points, proposing numerical integration or series approximation as potential methods.
  • A request for clarification is made regarding whether the cylinder is conducting or non-conducting, and whether the ends are open or closed.
  • A scenario is proposed where the cylinder is conducting, of finite length, with a uniform charge, and the point of interest is midway between the ends.
  • One participant argues that a conducting cylinder cannot maintain a uniform charge distribution.
  • Another participant agrees and then suggests considering a non-conducting cylinder with a uniform charge distribution instead.
  • A method is mentioned for solving the electric field problem by integrating the field or potential along the axis of a uniformly charged ring.
  • It is noted that while an equation can be derived for the field along the axis, finding a solution off the axis may be significantly more complex, potentially requiring non-standard functions.

Areas of Agreement / Disagreement

Participants express disagreement regarding the uniform charge distribution in conducting cylinders, with some asserting it is impossible while others propose alternative scenarios. The discussion remains unresolved regarding the general case of the electric field in hollow cylinders.

Contextual Notes

Participants have not reached consensus on the conditions under which the electric field can be calculated, particularly concerning the material properties of the cylinder and the configuration of the charge distribution.

n0083
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Hello,
Does anyone know of (or have a link to) an equation for the electric field at any point inside a a hollow cylinder shell of finite length?

thanks,
 
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I've never seen one. I suspect that it's not possible to get a closed formula for all points, and that you'd have to calculate it via numerical integration or using a series approximation of some kind.
 
More detail please. Is it a conducting cylinder kept at a given potential?
Are the ends open or closed?
 
Okay, let's simplify.

Suppose the cylinder is of finite length, and the point is inside the cylinder midway between the two ends. The ends are open. The charge is uniform and kept constant. The cylinder is made of conducting material.
 
That is impossible. A conducting cylinder will not have a uniform charge.
 
True that.

Suppose it is made of non-conducting material such that the charge is uniformly distributed.
 
That problem can be solved by taking the field or potential on the axis of a uniformly charged ring and integrating along the axis.
 
Right, on the axis you can get an equation for the field as a function of position fairly easily. Off the axis it's much more difficult, maybe even impossible, using "common" functions.
 

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