Gauss Definition and 648 Threads

  1. J

    Derive the relationship between Ricci scalar and Gauss Curvature

    Hi, I'm self-learning some physics topics and came across an exercise to derive the relationship between Ricci scalar and Gauss curvature in 2-surface, ##R=2K##, where ##K \equiv \frac {R_{1212}} {g}##; given the Ricci tensor ##R_{\alpha \beta} \equiv R^\lambda_{\, \alpha \lambda \beta}## and...
  2. tellmesomething

    Find the density of surface charges at the boundary of two conductors with different resistivities

    I tried using gauss law. This is how i set it up: I took a gaussian pill box of same area and very small length dx, the diagram is amplified for obvious reasons. Assuming theres a constant field in the yellow portion ##E_{1}## and a constant field ##E_{2}## in the green portion. I assume the...
  3. kirito

    Electric field of a sphere and a shell

    q encolsed =0 Second case q enclosed q by gauss law At 2r
  4. srnixo

    Gauss' law and the potential V (plane layer case)

    Here is the exercise: And these are my attempts: This is for the first question about the electric field. (I know I'm missing the drawing, which is a drawing of the plane layer of thickness 2e with a cylinder on it as a GAUSS SURFACE ). As for the second question, I'm not sure about it, so I...
  5. TheGreatDeadOne

    Surface Integral of a sphere

    Solving the integral is the easiest part. Using spherical coordinates: $$ \oint_{s} \frac{1}{|\vec{r}-\vec{r'}|}da' = \int_{0}^{\pi}\int_{0}^{2\pi} \frac{1}{|\vec{r}-\vec{r'}|}r_{0}^2 \hat r \sin{\theta}d\theta d\phi$$ then: $$I = \dfrac{1}{|\vec{r}-\vec{r'}|}r_{0}^2(1+1)(2\pi)\hat...
  6. L

    Gauss' Law for a conducting / non-conducting sheet

    The first image is for a conducting sheet (part of it anyway), the second is for a nonconducting sheet. Gauss' law seems to tell me that the electric field strength are different - they differ by a factor of two. Is this true? The charge enclosed in both of them are the same, and my intuition...
  7. S

    I How do I visualize the magnetic field?

    Hi! So my question is this, I have done measurements with an magnetic field meter around a transformer from 0.5 meter away (then measure some points around) and then I moved out 0.5 meters and so on until I reached a nearby building. So my issue now is I want to visualize this to my customer...
  8. M

    Gauss' law in line integral, Q=##ϵ_0 ∮E.n dl=-ϵ_0 ∮∂ϕ/∂n dl##

    I know the Gauss law for surface integral to calculate total charge by integrating the normal components of electric field around whole surface . but in above expression charge is calculated using line integration of normal components of electric field along line. i don't understand this...
  9. R

    Use Gauss' Law to calculate the electrostatic potential for this cylinder

    I solved laplacian equation. and got the solution of V(r, phi) = a. +b.lnr + (summation) an r^n sin(n phi +alpha n ) + (summation) bn r ^-n sin( n phi +beta n)
  10. BnayaMeir

    Surface Current and Electric Field

    Hi everyone! I'm pretty new in this forum, I found the topics here very relevant to my physics course. And here is my question: Given the following drawing, two infinite sheets (in y and z axis) of ideal conductive material. their thickness is infinitesimal (dx->0). The electric field is...
  11. A

    I Trying to derive Gauss' law using a cylindrical surface

    When I try to derive Gauss's law with a straight line of charge with density ##\lambda## through a cylindrical surface of length L and radius R, $$\vec E = \frac{\lambda*L}{4\pi\epsilon*r^2}$$ $$A = 2\pi*r*L$$ $$\vec E*A = \frac{\lambda *L^2}{2\epsilon*r} \neq \frac{q_{enc}}{\epsilon}$$ What am...
  12. J

    Calculating the Electric field inside an infinite planar slab using Gauss' Law

    Draw a Gaussian pill box that starts from 0 (half way between the slab) and extends towards 2 cm.$$A \times \int_{0}^{0.02} \rho dz$$ I'm not sure if I should multiply the integral by A (area) or V (volume) And if area would I multiply by 0.02^2? I'm confused here. Thanks for your help.
  13. J

    Gauss' Law applied to this Charged Spherical Shell with a small hole

    First draw a gaussian shape outside of the sphere (a larger sphere) with radius R. The total charge from the (inner) sphere will be: $$Q = \sigma A$$ $$A = 4\pi r^2$$ $$Q = \sigma 4\pi r^2$$ Use Gauss's Law to derive electric field magnitude $$\oint_{}^{} E \cdot dA = \frac{q_e}{\epsilon_o}$$...
  14. A

    Classical Exploring Gauss Principle of Less Constraints & Gibbs-Apell Equations

    In the usual literature about analytical mechanics, I find very little about the Gauss principle of less constraints and the Gibbs-Apell equations. I think the only treatment I've seen on Gauss is given In Lanczos's The variational principle of mechanics". So, I'm looking for introductory and...
  15. M

    Is Electric Flux Through a Half Sphere Zero According to Gauss' Law?

    Picture : My answer : I guess net electric flux is 0. so electric flux passing through surface 1 = -(electric flux passing through surface 2) and electric flux passing through surface 1 is EA = E(pi)(r^2) Is it correct? Thank you ...
  16. Leo Liu

    I Gauss' law and an object with nonuniform charge distribution

    Gauss' law: $$\iint_{\partial A}\vec E\cdot d\vec A=\frac{Q}{\epsilon_0}$$ Suppose we have a unevenly charged non-conducting spherical shell, in which a Gaussian surface is placed. In this case, is the electrical field on A 0, given that there is no charge inside A? I came up with this example...
  17. bluesteels

    Quick question about which radius to use on Gauss' law problem

    confused on part A/B when I look up they did E= Q/2e(0.8)^2. But why not use the 0.100mm because that is the area of the enclosed. Same with B why did they use 100m and not 0.8m because 0.8 is smaller so it enclosed the charge
  18. bluesteels

    Why Doesn't the E*A Equation Work for Electric Flux in This Case?

    Electric Flux = E*A = 5*6(0.05)^2. when i look up at other sources they use Electric flux = q/ (8.854*10^-12 [this is e]) equation but I am confused on why the E*A equation don't work. The answer is 0.02Nm^2/C
  19. Z

    On which objects can we apply Gauss' Law to find the electric field?

    What am I missing? I also don't get the title of the section: "Charge distributions with enough symmetry for Gauss's Law". I thought Gauss's Law was valid for any closed surface enclosing a charge. I don't understand what "enough symmetry" means in the title above. I get that with symmetry...
  20. E

    Gauss' law and flux concept issues

    Hi guys i have some concept issues about flux. My book says flux is proportional to the number of lines passing through that area. so my question is: first i am thinking that a 2D circle which has a 2r diameter and it is enclosing a 2q charge so its flux should be 2q/Epsilon.then i am thinking a...
  21. rudransh verma

    I Another way of stating Gauss' law?

    Gauss law relates the net flux phi of an electric field through a closed surface to the net charge q that is enclosed by that surface. It tells us that Phi = q/permittivity Can I say it like this : The gauss law states that the net flux of the surface depends upon the net charge enclosed by that...
  22. Leo Liu

    Gauss' law in differential form

    My book claims that the diff. form of Gauss' law is $$\nabla\cdot\mathbf E=4\pi\rho$$ Can someone tell me why it isn't ##\nabla\cdot\mathbf E=\rho/\epsilon_0##?
  23. C

    I Implementation of Correlated Gaussian Random Fields Model

    Hello everyone. I have been recently working in an optimization model in the presence of uncertainty. I have read https://www.researchgate.net/publication/310742108_Efficient_Simulation_of_Stationary_Multivariate_Gaussian_Random_Fields_with_Given_Cross-Covariance in which, a methodology for...
  24. H

    Find ##E_0## and ##k## for ##E= E_0 \sin(k r -\omega t)## using Gauss

    ##\nabla \cdot \vec{E} = \frac{\rho}{\epsilon_0}## ##\vec{E}_0 k cos(kr -\omega t) = \frac{\rho}{\epsilon_0}## ##E_0 = \frac{\rho}{\epsilon_0} / k cos(kr -\omega t)## and ##k^2 = (\arccos{\frac{\rho}{E_0 \epsilon_0}} + \omega t)/r## I don't think it makes sense since I found ##k = \pm...
  25. S

    Gauss' Law: Understand How to Calculate Flux

    Hello everybody To calculate the flux for the electric field I need the gauss law. There are two formula one with the integration over some area and the other is Q/e0. When do I have to use which one?
  26. M

    MHB Nodes and weight of Gauss Quadrature

    Hey! :giggle: Calculate the node $x_0$ and the weight $a_0$ of Gauss Quadrature so that $$\int_0^1w(x)f(x)\, dx\approx I_0(f)=a_0f(x_0)$$ where $w(x)=1+\sqrt{x}$. I have done the following: The Gauss quadrature formula with $(n + 1)=1$ node (i.e. $n=0$) integrates polynomials of degree $2n +...
  27. fluidistic

    Gauss' divergence theorem and thermoelectricity contradiction

    I get a nonsensical result. I am unable to understand where I go wrong. Let's consider a material with a temperature independent Seebeck coefficient, thermal conductivity and electrochemical potential to keep things simple. Let's assume that this material is sandwiched between 2 other materials...
  28. G

    I Problem about the usage of Gauss' law involving the curl of a B field

    I am trying to derive that $$\nabla \times B=\mu_0 J$$ First the derivation starts with the electric field $$dS=rsin\varphi d\theta r d\varphi $$ $$ \iint\limits_S E \cdot dS = \frac{q}{4 \pi \varepsilon_0} \iint\limits_S \frac{r}{|r|^3} \cdot dS $$...
  29. Y

    I How Gauss’ Law is applied to cylinders

    If I understand correctly, Gauss’ Law is (roughly) derived as follows: Part A Electric Flux = EA E = q / (∈4πr^2) A of the surface of a sphere is 4πr^2 They cancel out and therefore EA =q/∈ Line 4 seems to only apply to a sphere, as it is based on line 3. Now, Gauss’ Law is applied to...
  30. cwill53

    Using the solid angle to simplify an integral when deriving Gauss' Law

    I'm a bit confused on the derivation above. I understand what the goal of the derivation is, as it derives Gauss's Law using the solid angle, but i was wondering if someone could kind of fill in the steps the author skipped and explain the use of the solid angle.
  31. wcjy

    Electric field problem using Gauss' law: Point charge moving near a line charge

    F = qE ma = (2*10^-6) * (λ / (2pi*r*ε0) ) ma = (2*10^-6) * (4*10^-6 / (2pi*4*ε0) ) => I am not certain what to put for r ( But I sub in 4 because dist is 4) a = ( (2*10^-6) * (4*10^-6 / (2pi*4*ε0) ) )/ 0.1 a = 0.35950 v^2 = U^2 + 2 a s v = 0 u^2 = -2 a s => Can't sqrt negative so...
  32. R

    Using Gauss' Law to find the field at a point

    Attached is problem 23.03 from Halliday and Resnick. We have a sphere of uniform negative charge Q = -16e and radius R = 10cm. at the center of the sphere is a positively charged particle with charge q = +5e. We are supposed to use Gauss' law to find the magnitude of the electric field at...
  33. F

    I Asymmetry in Stokes' theorem & Gauss' theorem

    Stokes theorem relates a closed line integral to surface integrals on any arbitrary surface bounded by the same curve. Gauss theorem relates a closed surface integral to the volume integral within a unique volume bounded by the same surface. What causes this asymmetry in these 2 theorems, in the...
  34. R

    Does a square shaped line may have a circle shaped Gauss' surface

    Summary:: For finding the electric field at P in the photo below, may I select a gaussian surface circular? [Mentor Note -- thread moved to the schoolwork forums, so no Homework Template is shown]
  35. R

    I This linear system has a solution? (Gauss' elimination)

    I don't know the terms so I'm sorry if the informations at summary above is unclear. But I add a detailed photo of my calculations below. I use Gauss' Elimination laws.
  36. F

    I What is the orgin of Gauss' law?

    Was Gauss' law originally derived from theory or discovered by experiment?
  37. F

    I The 'outer surface' should be redefined when applying Gauss' law?

    Gauss' law dictates that charge will only appear on the outer surface of a conductor. But if there's charge in a conducting cavity, the inner surface of the conductor will accumulate induced charge. So what's outer or inner should be redefined?
  38. E

    Gauss' law for a physical capacitor with finite thickness plates

    In derivations of capacitance it is standard to consider two oppositely charged, infinitely thin sheets. If we construct a Gaussian cylinder across one sheet, we obtain ##E_{1} = \frac{\sigma}{2\epsilon_{0}}## for one sheet, and then we can superpose this field with that from the other at an...
  39. P

    Gauss' Law question about a conducting rod

    This is my attempt, i am confused at some points a. r = 0; The Electric field is 0 b. At r = a/2.00; I verified the answer and it is non zero, but my understanding is that the net charge should be on the surface of the conductor. Hence the charge q1=5*10^-15 C, should go to the surface of the...
  40. M

    Gauss' Theorem - Net Flux Out - Comparing two vector Fields

    Hi, I just have a quick question about a problem involving Gauss' Theorem. Question: Vector field F = \begin{pmatrix} x^2 \\ 2y^2 \\ 3z \end{pmatrix} has net out flux of 4 \pi for a unit sphere centred at the origin (calculated in earlier part of question). If we are now given a vector...
  41. P

    Gauss' law -- Conductor with a cavity

    I really don't understand the theory of the above kind of questions. But from the little theory i understand the Electric field is 0 inside the conductor and all the charge goes to the surface and distributes equally. a. Since the E=0 inside the conductor the point charge distributes outside...
  42. P

    Gauss Law Problem direction of Area

    My attempt is ∅ = ∫E.dA. The direction of E is going out of the net towards +ve i axis. I am not clear on the direction of the Area, it can be either +ve i-axis or -ve i-axis. Which direction should i consider? ∅ = ∫3.dA = 3*∫dA ---->1 ∫dA is the area of the circle. A = π * (0.11)^2 = 0.038...
  43. snoopies622

    I Simple case of Gauss' law for gravity

    i have little experience with the differential form of Gauss's Law, and I've tried three times now to arrive at it for a point mass M (spherically symmetric classical gravitational field) but instead of getting an answer proportional to the mass density I keep getting zero. Is the divergence...
  44. askcr9

    A slab? Infinite area? Electric field? Help please

    The first time I saw this question I had no idea how to do it (as you can see in the figure, I lost a lot of points :s) because I was confused on how to even approach it with area of the slab from all sides being infinity. Right? That's problematic, no? Today, I just tried the problem again for...
  45. The Bill

    Geometry Source for a coordinate-based formula for Gauss from Riemann

    I need a citeable source that gives the formula for the Gaussian curvature at a single point of an intrinsically defined Riemannian or Semi-Riemannian manifold given the intrinsic metric tensor and/or Riemann tensor. I've got sources for this already, but I'm not "allowed" to use them for this...
  46. torito_verdejo

    I Gauss' Law applicability on any closed surface

    I have read multiple threads on Physics Forums, Stackexchange and Quora, as well as the explanation of Gauss Law, but still don't understand the most fundamental aspect of it: its applicability for any kind of surface. More precisely, I don't get how this follows from the fact that...
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