Can Gauss' Law Be Applied Here?

In summary, the conversation discusses the use of Gauss' Law and the electric field equation to solve for the electric field at the center of a cup surface source charge. While the electric field equation can be used, there are requirements for using Gauss' Law, including symmetry of the charge distribution and the Gaussian surface. In this case, since the source charge is asymmetrical, Gauss' Law cannot be applied. However, it can still be used to calculate flux from knowledge of the charge distribution or vice versa.
  • #1
Taulant Sholla
96
5

Homework Statement


Capture.JPG


Homework Equations


Gauss' Law: ∫E⋅da = qenc0
E-field: E = kq/r2

The Attempt at a Solution


I solved this using electric field equation, differential elements, and integration. The correct answer is, I think, E=-q/(8πε0R2)

QUESTION: Can this be done via Gauss' Law? The source charge itself is a "cup surface." Here's my attempt...
Picture1.jpg
 
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  • #2
Taulant Sholla said:
I solved this using electric field equation, differential elements, and integration
And which way is that ##\vec E## pointing ? What is the ##R## there ?

The E you calculate using Gauss law, is it the same everywhere ? Pointing which way ?
 
  • #3
Taulant Sholla said:

Homework Statement


View attachment 95494

Homework Equations


Gauss' Law: ∫E⋅da = qenc0
E-field: E = kq/r2

The Attempt at a Solution


I solved this using electric field equation, differential elements, and integration. The correct answer is, I think, E=-q/(8πε0R2)

QUESTION: Can this be done via Gauss' Law? The source charge itself is a "cup surface." Here's my attempt...
View attachment 95495
I know of no way to use Gauss's Law to solve for E at the center. There's not the required symmetry.

What are the requirements for using Gauss's Law for such a purpose?
 
  • #4
There are no requirements to use Gauss' Law. I was wondering if it is possible. I assume since the source charge is asymmetrical, Gauss' Law can't be applied?
 
  • #5
Taulant Sholla said:
There are no requirements to use Gauss' Law. I was wondering if it is possible. I assume since the source charge is asymmetrical, Gauss' Law can't be applied?
If you're calculating flux from knowledge of the charge distribution, or vice versa, then you're correct.

However, if you use it to get the field from the charge distribution, there are requirements, involving symmetry, as well as the Gaussian surface which takes advantage of that symmetry.
 
  • #6
okay, thank you very much!
 

FAQ: Can Gauss' Law Be Applied Here?

Can I use Gauss' Law for this?

Gauss' Law is a fundamental law in electromagnetism that relates the electric flux through a closed surface to the charge enclosed by that surface. It can be used to solve a wide range of problems related to electric fields. However, there are certain factors that need to be considered before using Gauss' Law.

What are the conditions for using Gauss' Law?

Gauss' Law can only be used in situations where there is high symmetry in the distribution of charges. This means that the electric field must have a constant magnitude and direction throughout the surface. Additionally, the surface must be closed and the charge distribution must be static.

Can Gauss' Law be applied to any shape of surface?

No, Gauss' Law can only be applied to closed surfaces. These can be any shape as long as they are closed, meaning that they form a complete boundary without any openings. Open surfaces cannot be used with Gauss' Law.

How is Gauss' Law used to solve problems?

Gauss' Law is used to calculate the electric field at a point due to a charge distribution. The first step is to choose a closed surface that encloses the charge distribution. Then, the electric flux through that surface is calculated. Finally, using the electric flux and the enclosed charge, the electric field at the point can be determined using Gauss' Law.

Are there any limitations to using Gauss' Law?

Yes, there are some limitations to using Gauss' Law. As mentioned earlier, it can only be used in situations with high symmetry and for static charge distributions. Additionally, it is not applicable for situations with changing magnetic fields or for non-stationary charge distributions. In these cases, other laws and principles such as Faraday's Law and Ampere's Law must be used.

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