Question on Gauss law & charged disks

Click For Summary
SUMMARY

Gauss's Law is not applicable for calculating the electric flux density of a charged disk due to the lack of symmetry, which prevents the construction of a suitable Gaussian surface. In contrast, Coulomb's Law can calculate the electric field at any point, but deriving a general formula for electric flux density near the disk requires complex calculations, often resulting in an infinite series. Advanced techniques such as Green's function are necessary for solving Poisson's equation in graduate-level electromagnetism courses, particularly when using texts like Jackson.

PREREQUISITES
  • Understanding of Gauss's Law and its application in electrostatics
  • Familiarity with Coulomb's Law and electric field calculations
  • Basic knowledge of electric flux density concepts
  • Introduction to Green's function techniques in solving differential equations
NEXT STEPS
  • Study the application of Gauss's Law in symmetric charge distributions
  • Explore advanced techniques for solving Poisson's equation using Green's functions
  • Review the derivation of electric field equations from Coulomb's Law
  • Examine case studies involving charged disks and their electric fields
USEFUL FOR

Students and professionals in physics, particularly those studying electromagnetism, as well as educators seeking to deepen their understanding of electric field calculations and the limitations of Gauss's Law.

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
2K
  • · 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
1K
  • · Replies 17 ·
Replies
17
Views
2K
  • · Replies 7 ·
Replies
7
Views
3K