Deriving Electric Charge: Line, Ring, Cylinder, Cone, Sphere & Shell

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Homework Help Overview

The discussion revolves around deriving the formula for electric charge in various geometrical configurations, specifically focusing on a cylinder, cone, sphere, and shell. The original poster has already addressed several cases, including lines and disks of charge, and seeks assistance in setting up integrals for the remaining cases without using Gauss's Law.

Discussion Character

  • Exploratory, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the use of different coordinate systems for the various shapes, noting the relationships between the parameters in cylindrical and spherical coordinates. There is an emphasis on the setup of integrals for the remaining cases based on the previously derived ring of charge.

Discussion Status

Some participants express confidence in having the necessary information to proceed with setting up the integrals. There is a sense of progress, with acknowledgment of the previous work done by the original poster and others contributing to the discussion.

Contextual Notes

The original poster mentions a constraint of not using Gauss's Law for the derivations, which may influence the approaches discussed. Additionally, there is a reference to viewing a sheet of charge as a limiting case of a disk of charge.

Chris W
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Hi all. I need some help.
Without using Gauss's Law, I have to derive the formula for the electric charge for different cases.
-I already did few cases such as:
1. Infinite line of charge
2. Semi - infinite line of charge
3. Ring of charge
4. Semi - Ring of charge or any arc of charge
5. Disk of charge
6. Infinite Sheet of Charge

-I need to derive:
7. Cylinder of charge
8. Cone of charge
9. Sphere of charge
10. Shell of Charge

I know that the basic "building block" for cases 7-10 is the ring of charge which I already have. Basically what I need is the setup of the integral for cases 7-10.

Thank you

Chris W
 
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It's just an exercise in different coordinates. A cylinder has constant r, varying z and phi/theta in cylindrical coordinate, a cone has varying z, r and phi/theta in cylindricalm a sphere has varying, r, phi, theta in spherical and a shell has constant r, varying phi, theta in spherical
 
Thanks!

Yeah. Looks like I have all I need now I just have to set up the integrals.

Thanks! wow that was quick ... lol


please see what I have so far ... I hope all is good!

Thank you one more time

see attachment
 

Attachments

  • Infinite line of charge.jpg
    Infinite line of charge.jpg
    16.8 KB · Views: 580
  • Semi- infinite line of charge .jpg
    Semi- infinite line of charge .jpg
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  • ring of charge.jpg
    ring of charge.jpg
    17.2 KB · Views: 564
this is the rest of what I have so far

sheet of charge can be viewed as the disk of charge and letting the R go to the infinify
 

Attachments

  • disk of charge page 1of2.jpg
    disk of charge page 1of2.jpg
    17.9 KB · Views: 368
  • disk of charge page 2of2.jpg
    disk of charge page 2of2.jpg
    20.6 KB · Views: 369
  • semi-ring or arc of charge.jpg
    semi-ring or arc of charge.jpg
    20 KB · Views: 354

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