Flux Definition and 1000 Threads

Flux describes any effect that appears to pass or travel (whether it actually moves or not) through a surface or substance. A flux is a concept in applied mathematics and vector calculus which has many applications to physics. For transport phenomena, flux is a vector quantity, describing the magnitude and direction of the flow of a substance or property. In vector calculus flux is a scalar quantity, defined as the surface integral of the perpendicular component of a vector field over a surface.

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  1. M

    Understanding The Electric Flux of A Cube Rotated by an Angle Theta

    Hey, all, so I have been studying this problem all morning, and I do not understand two aspects to this example problem. I included a photo of the diagram used in this problem. You will see two cubes, but the diagram which corresponds to the problem below is the one on the right.PROBLEM: Find...
  2. D

    Circulation & Flux: Confirmation Needed | Differentiate1

    Here's my work: http://i.imgur.com/9ik31P5.png I need confirmation that the vector fields I found for parts 1) and 2) are correct. I also need to figure out how to find the flux in part 2) when the problem doesn't give any boundaries to evaluate. For part 1), the answer can be found by...
  3. R

    What Causes Delay in Magnetic Flux Propagation?

    Hey all, I'm working on a project now where I am using a solenoid driven at a 10Hz AC current to create a magnetic field on a solid piece of low carbon iron, and then using a smaller solenoid to capture the magnetic flux coming from the iron. By measuring the phase of the resulting waves...
  4. Entanglement

    What is the relationship between magnetic flux and coil wire?

    Magnetic Flux= BA is A the surrounding area affected by the flux or the area of the coil itself that is affected by the flux
  5. M

    Can someone explain the iron shavings flux line experiment to me?

    In regards to the famous experiment where a magnet is put under a sheet of paper with iron shavings on top, i don't understand why they distribute according to the shape of the magnetic lines of flux. (as seen in the link below)...
  6. zaidtaher

    MCNP Avg. Flux and Assembly Flux

    I want to know the best tally for MCNP Flux (avg and for each assembly) Please help
  7. PsychonautQQ

    Evaluate the Flux with Divergence Theorem

    Homework Statement Evaluate the flux where F = <(e^z^2,2y+sin(x^2z),4z+(x^2+9y^2)^(1/2)> in the boundary of the region x^2 + y^2 < z < 8-x^2-y^2 Homework Equations The Attempt at a Solution So using the divergence Theorem, ∇ dot F = 6 ∫∫∫6r dzdrdθ where z is bounded...
  8. PsychonautQQ

    Calculating Flux Through a Triangular Region with a Velocity Field

    Homework Statement Let v = -j be the velocity field of a fluid in 3 dimensional space. Computer the flow rate through the T of a triangular region with vertices (1,0,0) (0,1,0) (0,0,1) oriented with upward pointing normal vector Homework Equations The Attempt at a Solution So can...
  9. E

    Understanding Flux Density in Coils: Equations and Factors Explained

    Hello, I am looking into magnetic flux density in coils can anyone tell me if there is a general equation that equates flux density to the electric current, the coil's dimensions and number of turns? Any help would be appreciated. Thanks.
  10. Saitama

    Finding flux through a part of infinite disc

    Homework Statement A charge ##(5\sqrt{2}+2\sqrt{5})## coulomb is placed on the axis of an infinite disc at distance ##a## from the centre of disc. The flux of this charge on the part of the disc having inner and outer radius of ##a## and ##2a## will be A)##\dfrac{3}{2\epsilon_0}##...
  11. P

    Flux through oddly shaped cylinder

    Homework Statement Homework Equations The Attempt at a Solution Here are my attempt. The top is when i tried using cylindrical coordinates. Instead of using dA=(cosθ i +sinθj)rdzdθ I used (cosθ i +sinθk)rdydθ since the cylinder is going along the y-axis rather than z. The...
  12. PsychonautQQ

    How Do You Calculate the Flux of a Vector Field Through a Hemisphere?

    Homework Statement F has a vector potential A = <x,y,x^2+y^2>. Find the flux of F through the upper hemisphere x^2+y^2+z^2=1 z≥0 oriented with upward pointing normal vector The Attempt at a Solution So if F has a vector potential A, would you take the gradient of A to get F? in...
  13. S

    Flux in Moderator vs Flux in fuel

    I was reading about different flux shapes, and it depicted the the shape of the fission neutron spectrum to be in the shape of y=e^-x*sinh(sqrt(x)), where y is the spectrum and x is the energy in MeV. note: put that equation into wolfram for easy visualization Then it depicted the slowing down...
  14. G

    Questions on conditions for calculating flux integrals?

    Conditions for calculating flux integrals? [Figured it out] If one uses Stokes' theorem and if two oriented surfaces S1 and S2 share a boundary ∂s then the flux integral of curl(F) across S1 equals the flux integral of curl(F) across S2. However, in general it won't be true that flux integral G...
  15. B

    Help with theory about magnetic flux loops and tornados

    hi i have some crazy ideas about tornadoes,lightning and storms emitting magnetic flux loops interacting with the Earth's own magnetic properties and do not have enough electrical schooling to know if it is even a possibility. i was hoping i could get a more learned opinion. the thread is...
  16. P

    Fraction of incident flux that escapes from a star

    If the flux entering such an atmosphere from the core of the star at a radius is r0 is F0, the flux that reaches radius r is given by F(r)=F0*e^k(r^-2-r0^-2) where k is a constant a) Write down a formula for the fraction of the incident flux that escapes from the star entirely...
  17. P

    Flux that reaches a certain radius in a star

    I know the radiative flux traveling through the atmosphere of a star obeys the equation: dF/dr=-opacity*F*density If we have an isothermal atmosphere the density decreases with radius such that density is proportional to 1/r^2. If the flux entering such an atmosphere from the core of...
  18. I

    Neutron Flux Profile in a Spherical Moderator

    Hello People I need help with the following assignment: It states: Consider an ideal moderator with zero absorption cross section, Ʃa = 0, and a diffusion coefficient, D, which has a spherical shape with an extrapolated radius, R. If neutron sources emitting S neutrons/cm3sec are distributed...
  19. 1

    Which axis does flux pinngin work on?

    i've seen all the super conductors and how it fixes a magnetic field and then levitates, but on which direction does it fixes? for example: if there was a solenoid pointing upwards(the empty middle is vertical) and moving from the axis of -Y to +Y and a ring of super conductor places higher...
  20. V

    Electric flux leaving a sphere

    Homework Statement Within the spherical shell, 3 < r < 4 m, the electric flux density is given as D = 5(r − 3)3 ar C/m2 a) What is the volume charge density at r = 4? b) How much electric flux leaves the sphere r = 4? Homework Equations ρv=Div D Electric flux = ∫sD.ds=∫vρvdvThe Attempt at a...
  21. B

    Calculating Flux through a Sphere using Cylindrical Coordinates

    I was told it might be better to post this here. Homework Statement The trick to this problem is the E field is in cylindrical coordinates. ##E(\vec{r})=Cs^2\hat{s}## Homework Equations ##\int E \cdot dA## The Attempt at a Solution I tried converting the E field into spherical...
  22. B

    Flux Through Sphere: Cylindrical Coordinates

    Homework Statement The trick to this problem is the E field is in cylindrical coordinates. ##E(\vec{r})=Cs^2\hat{s}##Homework Equations ##\int E \cdot dA##The Attempt at a Solution I tried converting the E field into spherical coords and I can find the flux that way but it is a complicated...
  23. V

    Electric flux passing through a plane

    Homework Statement Given a 60-μC point charge located at origin, find the total electric flux passing through the plane z = 26 cm. Homework Equations The Attempt at a Solution Since electric flux lines from a point charge emanate in every possible direction, only a quarter of...
  24. N

    Magnetic flux through triangular ring

    Homework Statement Very long wire carrying current I is surrounded by a brass ring of a triangular cross section. (figure attached) Show that ψ = μ° I h ------ (b - a ln ((a+b)/b) 2∏b Homework Equations A = (μ°I/2∏ * ln x) az (according to one of the solutions, where x is the...
  25. C

    Relationship between radiation flux and count rate of a scintillator

    If the radiation flux is calculated as: F = \frac{L}{2*pi*r^{2}} where L is the luminosity of the source and r is the distance from the source and the count rate of a scintillator \frac{number-of-scintillations}{time} What is the relationship between them? There obviously should be one, as...
  26. J

    Transformers : flux leakage and saturation current

    Can anyone explain why saturation current and flux leakage are not related? saturation current = current where all the magnetic domains are aligned right? flux leakage = flux from the primary that doesn't reach the 2ndary can someone also explain why, flux leakage causes a increase in...
  27. O

    What is the flux through each face of the pyramid?

    Homework Statement base of pyramid is a 6m x 6m square height of pyramid is 4meters. a 52 N/C E field orthogonal to the base of the pyramid Homework Equations EA cos theta The Attempt at a Solution if flux through base = EAcos theta = 52 (36m^2) cos(0) = 1872 N m^2 / C Area...
  28. 2

    Magnetic flux pinning sometimes there and sometimes not.

    Hello. As far as I know about superconductors, if you put a superconducting material in a magnetic field and then cool that material below its critical temperature, the material should lock to that magnetic field (magnetic flux pinning). Now I have seen videos where the locked magnet/material is...
  29. F

    Solving Flux Graphs - Need Help!

    Homework Statement The second picture contains the problem statement. I am having a bit of trouble drawing the graphs asked for. Homework Equations See below The Attempt at a Solution I have drawn what I think is correct. In the first graph, I show the flux of the cart must...
  30. M

    Find Force from Flux: Solar Sail at 3 AU

    Homework Statement What is the flux on a solar sail per square meter, if it orbits the Sun at 3 AU. Flux at 1 AU is 1.36 KW/square meter Homework Equations Flux goes as 1/r^2 The Attempt at a Solution Flux at 3 AU will be 1.36/3^2 = 1.36/9 = 0.15 KW/square meter I can't...
  31. M

    A point charge Q is located on axis.Find flux

    A point charge Q is located on the axis of a disk of radius R at a distance b from the plane of the disk Show that if one fourth of the electric flux from the charge passes through the disk, then R= √3 b I have looked it through all angles possible for me but it seems to evade me. Got...
  32. S

    Analyzing Assumptions for Neutron Flux: Fast & Thermal Groups

    Assumptions 1) a=absorption 2) f=fission 3) ∅=neutron flux 4) time independent 5) group 1, fast neutrons 6) group 2, thermal neutrons 7) All fission neutron are boring in fast group 8) All neutrons created by thermal group, thus vƩf2 exists vƩf2 does not 9) Down scattering occurs but up...
  33. H

    Electric Flux, Gauss's Law Problem

    Homework Statement A proton is a distance d/2 directly above the center of a square of side d. What is the magnitude of the electric flux through the square?Homework Equations 1. Electric flux, \Phi_{net} = \oint \vec{E}\cdot d\vec{A} 2. \Phi_{net} = \frac{q_{enc}}{\epsilon_{0}} 3. \vec{E} =...
  34. Y

    How Do You Calculate Magnetic Field Magnitude for a Specific Flux?

    Homework Statement A horizontal rectangular surface has dimensions 3.10cm by 3.05cm and is in a uniform magnetic field that is directed at an angle of 34.5∘ above the horizontal. What must the magnitude of the magnetic field be in order to produce a flux of 4.5E-4 Wb through the surface...
  35. J

    Calculate Displacement Current from Electric Flux Density

    Homework Statement If electric flux density (D) is given by the vector (xy,yz,xz) then calculate the displacement current density Homework Equations Jd = dD/dt The Attempt at a Solution if you differentiate D, in terms of t, then you just get 0..but that apparently isn't the answer
  36. D

    Electric Flux Density: 4.5Xe + .50MV/m

    Homework Statement Given Xe=4.5 and E=.50 MV/m find the displacement flux densityHomework Equations D=ε0εrE εr=1+XeThe Attempt at a Solution Using the equation above I get (8.85e-12)(5.5)(.50e6)=.000024338 C/m^2 which is not what the answers say they give it in nC which I can't see how they can do?
  37. vmr101

    Calculate the electric flux piercing a cube?

    Homework Statement Consider four point charges q1, q2, q3 and q4, located at r1, r2, r3 and r4, respectively. (a) Calculate the electric flux piercing a cube (with side a and centered at r0 = (0, 0, 0) that contains all of these charges. (b) Calculate the electric field of the four charges...
  38. T

    Comparing Flux of a Closed Cylinder

    Homework Statement A closed cylinder consists of two circular end caps and a curved side. A negatively charged particle is placed outside the left end of the cylinder, on its axis. Compare the flux through the left end of the cylinder with that through the right. 2. The attempt at a...
  39. P

    Electric flux through a surface

    Homework Statement A point charge q is situated a distance d/2 above a square surface of side d as shown (see attached). a) It cannot be determined b) 2q/ε0d c) q/4\piε0 d) q/\piε0d2 e) q/6ε0 Homework Equations \Phi=qenc/ε0=\ointE*dA The Attempt at a Solution Shouldn't the...
  40. D

    Engineering Flux density in magnetic circuit

    Homework Statement Consider the magnetic circuit shown in figure 3 Assuming that the core (μr=1000) has a uniform cross section of 4 cm^2, determine the flux density in the air gap the picture is very small so here are the values L=42cm, Ig=0.1cm, turns=500, and I=0.2A Homework Equations...
  41. C

    Induction, magnetism (flux), and current

    Hi, inductance is the property of a conductor by which a change in current in the conductor "induces" (creates) a voltage (electromotive force) in both the conductor itself (self-inductance). --wikipedia From what I understand, the inducing happens due to the resulting change in magnetic field...
  42. M

    Flux calculation using Gauss’s Theorem

    Qn: A uniform electric field of strength 300 N/C at an angle of 30º with respect to the x-axis goes through a cube of sides 5 cm. (a) Calculate the flux through each cube face: Front, Back, Left, Right, Top, and Bottom. (b) Calculate the net flux through the entire surface. (c) An electron...
  43. Y

    What Is the Net Electric Flux Through Each Closed Surface?

    Homework Statement The three small spheres shown in the figure below carry charges q1 = 4.30 nC, q2 = -7.70 nC, and q3 = 3.40 nC. Find the net electric flux through each of the following closed surfaces shown in cross section in the figure. Homework Equations...
  44. T

    Electic Flux through a cube Why am I getting a value?

    Homework Statement A cubical Gaussian surface is placed in a uniform electric field as shown in the figure to the right. The length of each edge of the cube is 1.0 m. The uniform electric field has a magnitude of 5.0 * 10^8 N/C and passes through the left and right sides of the cube...
  45. I

    Why is this wrong? (gravitational flux)

    in my notes i have.. \Phi = \int \vec{g}\cdotdA = g(4\pir2) = -\frac{GM}{r^2}(4\pir2) which yields \vec{g}=-\frac{GM}{r^2} here's what i did independently.. \Phi = \int \vec{g}\cdotdA = -\frac{GM}{r^2}(4\pir2) but since \vec{g}= -\vec{\nabla}\Phi ie... \vec{g}=\frac{d \Phi}{dr}=\frac{4...
  46. O

    Flux across a plane with varying electric field

    Homework Statement I got home from a test, had an extra credit problem semi memorized and am wondering how I was suppose to solve. http://i.imgur.com/cIOdSvk.png A plane with sides L is at x=3 . An electric field E = α y^2 x i + α z^2 y j passes through (where \alpha is a constant). Find the...
  47. D

    Find the dielectric flux and polarization values

    Homework Statement In a slab of Teflon (εr=2.1), the electric field is E= 6Ux+12Uy-20Uz V/m. Find D and P (BTW εr stands for the relative dielectric constant) Homework Equations D=(ε0)(εr)E P=D-(ε0)E The Attempt at a Solution (a)...
  48. D

    Find Flux Through Cube & Sphere

    Flux through sphere Homework Statement Given \vec{F}=\frac{\vec{r}}{r^2} and unit sphere, find the flux through the surface of the cube. Homework Equations Surface Integral of F dS=volume integral of Div. F d^3r The Attempt at a Solution After the above formula, I do not have...
  49. FOIWATER

    When does the surface charge density equal the electric flux density?

    Homework Statement The electric field intensity in polystyrene (relative permittivity 2.55) filling the space between the plates of a parallel plate capacitor is 10kV/m. The distance between the plates is 1.5mm. Calculate the surface charge density of free charge on the plates, and the surface...
  50. T

    How Does Divergence Relate to Flux in a Rectangular Prism?

    Homework Statement This is a coursework problem. I am having issues understanding the concepts on this one topic - divergence and how it relates to flux. I have attached screenshots that honestly give the best representation of my issue but I will set up the issue I am having...
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