Question on Gauss law & charged disks

Click For Summary

Discussion Overview

The discussion revolves around the application of Gauss's Law and Coulomb's Law in calculating the electric flux density of a charged disk. Participants explore the limitations of Gauss's Law in this context and the challenges of using Coulomb's Law for deriving general formulas versus point calculations.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants suggest that Gauss's Law is typically applicable in highly symmetric situations where a Gaussian surface can be constructed, making it easier to calculate electric flux.
  • Others argue that while Coulomb's Law can calculate the electric field at any point, deriving a general formula for the electric flux density near the disk is complicated due to the lack of symmetry.
  • A participant mentions that calculating the electric field at points off the axis of symmetry may lead to more complex solutions, potentially involving infinite series.
  • There is a contention regarding whether Coulomb's Law can be considered a general formula for calculating the electric field, with differing interpretations of its applicability in this scenario.

Areas of Agreement / Disagreement

Participants express differing views on the applicability of Gauss's Law and Coulomb's Law, indicating that there is no consensus on how to approach the calculation of electric flux density for a charged disk.

Contextual Notes

The discussion highlights limitations related to symmetry in the application of Gauss's Law and the complexity of using Coulomb's Law for general cases, but does not resolve these issues.

mazen_zone
Messages
17
Reaction score
0
hey everyone...

i want to know why can't we use Gauss law to calculate the electric flux density of a charged disk?

and how to calculate it "everywhere"? as coulomb's law calculates it at a certain point only...
 
Physics news on Phys.org
mazen_zone said:
hey everyone...

i want to know why can't we use Gauss law to calculate the electric flux density of a charged disk?

You need to realize when Gauss's Law are typically used - in highly-symmetric situation where you can construct a Gaussian surface that will have an electric flux that is either a constant, or zero. When you can do that, then using Gauss's Law will be quite easy. If not, it is seldom solvable in closed form mathematically.

and how to calculate it "everywhere"? as coulomb's law calculates it at a certain point only...

That's not right. You CAN use Coulomb's law to calculate the field at any point - it doesn't mean you can solve it EASILY. Again, because of the lack of symmetry, calculating at field points off the axis of symmetry will make the solution more involved (you will end up with an infinite series since there may be no closed form of the solution). When you get to a graduate level E&M course using texts such as Jackson, you WILL learn how to solve this using "Coulomb's Law", i.e. using Green's function technique to solve the Poisson's equation.

Zz.
 
yeah i know coulombs law can calculate the electric flux at any point, i meant i can't use it to derive a general formula to calculate the electric flux density at any point near the disk like Gauss law, but i have to remake the calculations at every point that i want the flux at...

correct me if I'm wrong...
 
mazen_zone said:
yeah i know coulombs law can calculate the electric flux at any point, i meant i can't use it to derive a general formula to calculate the electric flux density at any point near the disk like Gauss law, but i have to remake the calculations at every point that i want the flux at...

correct me if I'm wrong...

I have no idea what you just said.

Coulomb's Law IS a "general formula" to calculate E-field.

Zz.
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 9 ·
Replies
9
Views
3K
  • · Replies 7 ·
Replies
7
Views
1K
  • · Replies 83 ·
3
Replies
83
Views
5K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 29 ·
Replies
29
Views
2K
  • · Replies 30 ·
2
Replies
30
Views
3K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 17 ·
Replies
17
Views
2K