Derive the Analog of Gauss' law

In summary, the conversation discusses a problem involving Gauss' law and the related equations for electric potential and electric field. The person is stuck on part (d) and is seeking help to solve it. They mention that they have basic knowledge of Gauss' law and explain how it is related to the equations for electric potential and field. They also provide the necessary equations and suggest integrating to find the charge contained in the region. They then leave the rest of the solution for the person to work out.
  • #1
KT KIM
24
0
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I am stuck with this (d) all the other (a),(b),(c) were just like
(a) E= −∇φ
(b) ∇ · E= −∇2φ
(c) ∇ × E

I know only very basic about Gauss' law, the problem is not from Electrodynamics course.
I don't know what should I do to solve (d)
 
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  • #2
Gauss' law is:
[tex] \nabla \cdot E = \rho / \epsilon_0 [/tex]
We also know that by definition, potential and electric field are related by
[tex] E = - \nabla \cdot \phi [/tex]
So we then have
[tex] -\nabla^2 \phi = \rho/\epsilon_0 [/tex]

You know the form of phi, so you can just integrate over r from 0 to R to get the charge contained in the region. Since there's no angular dependence, 4pi comes out, and it's just a simple integral over r.
[tex] - 4\pi \epsilon_0 \int \limits_0^R (\nabla^2 \phi) r^2 dr = Q [/tex]

I'll let you work out the rest.
 
  • #3
Thankyou!
 

What is Gauss' Law?

Gauss' Law is a fundamental law in physics that relates the electric flux through a closed surface to the enclosed electric charge. It states that the electric flux through a closed surface is proportional to the enclosed charge, and is also affected by the permittivity of free space.

What is the analog of Gauss' Law?

The analog of Gauss' Law is a similar law that applies to other physical quantities, such as magnetic flux, gravitational flux, and fluid flow. It follows the same principle as Gauss' Law, relating the flux through a closed surface to the source of the field.

How do you derive the analog of Gauss' Law?

The analog of Gauss' Law can be derived using a similar method to Gauss' Law. It involves taking the surface integral of the physical quantity over a closed surface, and relating it to the source of the field using the appropriate constant.

What are some applications of the analog of Gauss' Law?

The analog of Gauss' Law has many applications in various fields of physics and engineering. It is used to calculate the magnetic field around a current-carrying wire, the gravitational field around a massive object, and the flow of fluids through a closed surface.

Are there any limitations to the analog of Gauss' Law?

Like Gauss' Law, the analog of Gauss' Law has limitations and assumptions. It assumes that the physical quantity being considered is continuous and that the source of the field is located at a single point. It also does not account for any boundary or surface effects.

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