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. P

    Surface flux through a single finite element

    Hi, I'm facing a real-life problem and I don't what specific mathematics topic it's related to. Homework Statement I know the value of the components of a vector field in three points of space and I have to find the flux of this vector field through the surface defined by those...
  2. T

    How does wireless power transfer produce magnetic flux?

    From what I learned, for an electric current to be induced in a wire, there must be a magnetic flux. On youtube, there are lots of videos showing wireless power transfer to a lightbulb or LED. However, the light is constant. How is the magnetic flux changing in such a setup?
  3. O

    Electric flux - Area vector question

    This is my first post here. I have a problem dealing with Electric flux. According to Gauss's Law, to find electric flux we use equation: ψ=∫D dot dA, both D(Electric flux density) and dA(super small area normal to the surface) are vector quantity. Now this is what I confused, how...
  4. A

    What is the difference between Surface and Flux Integrals?

    Hi, so this is my first time on this forum and I've just gotten very frustrated with trying to understand this one problem. I got part A by using divergence theorem but I don't know how go about computing part B. Suppose F⃗ (x,y,z)=⟨x,y,5z⟩. Let W be the solid bounded by the paraboloid...
  5. Einj

    Deep inelastic scattering: quention on the Hand convention for the flux.

    Hi all. I'm studying deep inelastic cross section in parton model. In particular I'm referring to Halzen-Martin's "Quarks and leptons" section 8.5, but I think this is a quite generale procedure. In studying the deep inelastic scattering by e- on proton it cuts off the electron part and work...
  6. P

    Problem: flux through prism faces

    I need help regarding a practical problem I'm facing. It's not a homework/coursework, It's a real-life problem. I have the values of a vector field (wind) given in six coordinates in 3D space. Those coordinates are the vertices of a triangular right prism (looks similar to my problem...
  7. N

    Flux through a cube at an angle

    Homework Statement A uniform electric field with a magnitude of 600 N/C is shown pointing in the y-z plane, at 30 degrees from the +y axis and at 60 degrees from the +z axis. This electric field passes through a cube, with each side of length 2.0cm and oriented with faces in the +x, +y, and +z...
  8. I

    Trying to increase the magnetic flux density

    Hello all, long time follower, first time poster. (Also feel free to move this if it's not in the right section.) Basically I have this mechanism pictured here: You can imagine that the drawing is of a top view of a section cut of the total mechanism. This is the radius view, the full diameter...
  9. C

    Which Gaussian surfaces have an electric flux of +q/εo through them

    Which Gaussian surfaces have an electric flux of +q/εo through them? I think is b since in c, +q and -q cancel each other out, d is only -q is that the right approach? thanks!
  10. E

    Making Flux Negative in a Constant Vector Field Help

    Homework Statement I know I posted a question yesterday also, but this homework is getting on my nerves. My prof isn't the best out there. So basically the question is as follows: http://img812.imageshack.us/img812/8130/problem6.png Homework Equations Not sure, I sort of answered the...
  11. W

    Axial Flux PMG Testing for 100W Wind Turbine - William

    Hey everyone. I've been working on a axial flux permanent magnet DC generator to use on a 100W wind turbine(small I know), to charge 12v batteries in low wind speed areas. Now that it's complete, I'd like to determine the full power curve at different rpms. So far I've been running it on NO...
  12. W

    Axial Flux PMG Testing for 100W Wind Turbine - William

    Hey everyone. I've been working on a axial flux permanent magnet DC generator to use on a 100W wind turbine(small I know), to charge 12v batteries in low wind speed areas. Now that it's complete, I'd like to determine the full power curve at different rpms. So far I've been running it on NO...
  13. D

    Understanding Flux Between Two Magnets

    I know that when there's a magnet next to a piece of iron, the former's flux density just travels across the air gap between them provided it's small enough. But what happens when there's two magnets next to each other? I know B follows the superposition principle, so do their flux densities...
  14. M

    Magnetic Flux Quanta - Definition & Animation

    What is "Magnetic flux quanta"? is there any animation describing this subject?
  15. alv

    EMF v time graph vs change in flux v time

    I'm actually a teacher and I can't explain this problem from the 2007 HSC. I've attached a copy of the question and the two graphs. The question shows a graph of change in magnetic flux vs time and asks you to choose which graph of induced emf best fits it. I don't understand why the induced emf...
  16. I

    Electric flux through a closed surface

    [EDITED] Why is the electric flux through a closed surface zero? My book based the reasoning from a uniform electric field. I understand that for a uniform electric field, the electric field doesn't diminish in magnitude as we move away from the source, and if we construct a box-shaped closed...
  17. C

    FEM tools like MAXWELL , FLUX , MOTOR CAD

    Hi all, I want to learn tools like MAXWELL 2d 3d , MAGNET, FLUX etc. I want to know if I'll need to know CAD and FEM Analysis to learn the above mentioned tools. Thankyou, Chaitanya
  18. Z

    Understanding Griffiths' Flux Rule Derivation for Motional EMF

    Hi, the attached picture should show Griffiths derivation of the flux rule for motional emf. To refresh your memory it says that minus the rate of change of the magnetic flux equals the emf: -d\Phi/dt = \epsilon Now, I need some help in understanding the attached derivation. Griffiths...
  19. J

    Iron rod - will flux link with disk above it

    If an aluminium disk is placed above a COMPLETELY vertical current carrying iron rod will any flux link with the aluminium disk... Firstly, does it matter if the current is AC or DC. I presumed not as the only difference is that the magnetic field will vary in one case and stay constant in...
  20. P

    What is measured in a fast reactor for power calculation : fast neutron flux or

    What is measured in a fast reactor for power calculation : fast neutron flux or overall ( fast + thermal) neutron flux ? My doubt is : The fission chambers used for measuring neutron flux undergo chemical reactions due to which type of neutron : fast or thermal ?
  21. DryRun

    Evaluating Normal Outward Flux of Vector Fields

    Homework Statement Vector field ##\vec F= 4x \hat i+4y \hat j +3 \hat k## Let S be the open surface above the xy-plane defined by ##z=4-x^2-y^2## a. Evaluate normal outward flux of F through S. b. Use Stokes' theorem to evaluate the normal outward flux of ##∇ \times \vec F## through S. c...
  22. B

    Is My Magnetic Flux Homework Solution Incorrect?

    Homework Statement Please let me know whether it's wrong for my attached solution. Homework Equations i = (d∅/dt)/R The Attempt at a Solution In part (d), does it calculate wrong?? In part (e), where has the dissipated energy? is it for heat energy?? Thanks!
  23. B

    Calculating Magnetic Flux: A Troubleshooting Guide

    Homework Statement Please let me know whether it's wrong for my attached solution. Homework Equations magnetic flux = BAcosθ The Attempt at a Solution I don't know how to calculate the part (c) as attached file, please advise!
  24. N

    Magnetic Flux inside a Transformer

    I have read that when the secondary of a transformer has current flow, it will reduce the magnetic flux in the core. This then reduces the back-emf on the primary, causing a increase in current to reestablish the magnetic flux to what it once was. What I want to know is when the secondary...
  25. R

    Calculating moleculalar flux from deposition rate.

    I have deposition rate of Silicon dioxide as 1000A/minute. I need to calculate molecular flux to the surface. First I tried to use ideal gas theory but since SiO2 is not ideal gas therefore my answer was completely wrong. I am disoriented. Can anybody help. I know the answer is 3.8E15...
  26. I

    Will a Knotted Flux Tube in a Plasma Tend to Move?

    Suppose I have a plasma. Inside the plasma is a knotted flux tube in an electric field. Will it tend to move? Is this there a better forum for this question?
  27. J

    Compute the flux of vector field through a sphere

    Homework Statement Compute the flux of the vector field F(x,y,z)=(z,y,x) across the unit sphere x2+y2+z2=1 Homework Equations I believe the forumla is ∫∫D F(I(u,v))*n dudv I do not know how to do the parameterization of the sphere and then I keep getting messed up with the normal vector.*...
  28. Z

    Problem with calculating magnetic flux for a single coil of wire.

    Homework Statement This is more of a general question about magnetic flux in a uniform magnetic field, but I think this is the correct place to post it. I understand that magnetic flux through an area A is the product of the magnetic flux density B and the projection of area A onto a surface...
  29. A

    Why isn't the magnetic flux of a loop infinite?

    If B~1/r2, then if we have a simple loop, B near the inner edge of the loop will be infinite (or close to it). Why then, would our flux not be infinite? I also get infinity if I take ∫ ∇ X A *da =∫B*da =∫(closed)A*dl Since A ~1/r and r~0 at the limit of our surface integral. I know I am...
  30. G

    Flux through loop around solenoid

    Homework Statement A simple loop of 5 cm radius encompasses the middle turns of a long coil. The coil has 2500-turns, is of length 1 m and radius 1 cm, and carries a current of 10 Amps. What is the magnetic flux through the single loop? Homework Equations B=μIN/L with L=1: B=μIN...
  31. P

    What is the flux through one face of the cube? Is my answer correct

    Homework Statement A point charge Q is placed at the center of a cube of side L . What is the flux through one face of the cube? Express your answer in terms of some or all of the variables Q ,L and appropriate constants. The Attempt at a Solution I'm getting Q/6e0 , is this...
  32. D

    Question about changing magnetic flux

    Homework Statement A 200-loop coil of cross sectional area 8.5 cm2 lies in the plane of the page. An external magnetic field of 0.060 T is directed out of the plane of the page. The external field decreases to 0.020 T in 12 milliseconds. What is the magnitude of the change in the external...
  33. B

    Magnetic Flux Through Wire Loop

    Homework Statement A wire loop with radius R is located a distance d from a long straight wire carrying a current I. Find the flux through the loop. Homework Equations B = \muI/(4\pi) Magnetic Field above wire \phi=B*da*cos\vartheta The Attempt at a Solution Somehow you have to...
  34. P

    Question About Flux of Surfaces: Need Explanation

    I have attached a file with my question. From what i see the flux for both surfaces will be 0. I am unsure and need a little of explaining
  35. C

    Flux of a Vector Through a Surface: x²+y²=8, z-x²-y²=0

    Homework Statement The velocity of a fluid is given, in cartesian coordinates (x, y, z), by \vec{v} = v_{0}x\hat{z} being a constant with velocity dimensions. a) Calculate the flux of this vector through the closed surface composed by z-x²-y²=0 and by the plan z=8 limited by the circle with...
  36. I

    Flux tubes in a Type II Superconductor

    What would happen if a magnetic field is generated inside of a Type II superconductor? Would there be flux tubes?
  37. 1

    Flux through a spherical surface

    Homework Statement Calculate the flux of vector field F = -3r through sphere radius 5 at the origin. Homework Equations The Attempt at a Solution Since the orientation is always exactly opposite of the orientation of the surface, I expect a negative answer. Also, since they...
  38. A

    Flux integral over a closed surface

    So we recently began electrostatics and here you encounter Gauss' law saying that the flux integral of an electric field E over a closed surface is only dependent on the charge confined within the surface. Now for a sphere that's pretty obvious why. Because since the field gets weaker...
  39. Z

    Understanding Electric Field Flux: Explained with Physical Interpretation

    Can anyone tell me the physical interpretation of the flux of an electric field through a closed surface. I think I do understand what flux is: Like in a water pipe a flux integral over the surface of the pipe would be the volume of water passing through the surface per second. What is the...
  40. M

    Factors that would increase magnetic flux through a coil?

    24. A square coil is perpendicular to a uniform magnetic field. Which one of the following would increase the magnetic flux through the coil? A. Decreasing the area of the coil. B. Increasing the number of loops in the coil. C. Removing the coil from the magnetic field. D. Increasing the...
  41. S

    Finding the flux of an electrix field

    Homework Statement A charge q sits in the back corner of a cube, as shown in the attachment. What is the flux of E through the shaded side? Homework Equations The Attempt at a Solution I know that I need the surface integral of E over the shaded area, but the problem is with...
  42. C

    Magnetic Flux Q&A: Can Length Contraction Alter Quanta?

    Can I alter the quanta of magnetic flux using length contraction of the source creating the B field. Like for example could I get half of the flux by moving relative to the B field. Or some other fraction of it. The unit of flux is like \frac{h}{2e}
  43. T

    Motional emf, Gaussian flux, and lenz's law help

    Homework Statement Two bars, each 30cm long, and each having a resistance of 2-ohms, are connected to a 1,500 volt battery. The bars are attached to each other with 3 insulating springs, each having a spring constant of 9N/m. The two bars are initially at rest, 4cm apart. The switch is...
  44. T

    How Does Gauss's Law Apply to Oscillating Bars in an Electrical System?

    Question about Gauss flux?? Homework Statement Two bars, each 30cm long, and each having a resistance of 2-ohms, are connected to a 1,500 volt battery. The bars are attached to each other with 3 insulating springs, each having a spring constant of 9N/m. The two bars are initially at rest...
  45. K

    Energy flux versus temperature change

    If I have two spheres of the same radius, they can still have different temperatures. However: What if the colder sphere is closer to the ideal of being a blackbody than the hotter sphere? http://en.wikipedia.org/wiki/Emissivity In an open system without internal energy generation, both...
  46. B

    Magnetic Field Induced by Nonuniform Electric Flux

    Homework Statement During the design of a new doppler radar unit, you have two circular plates with radius R = 3 cm and a plate separation of d = 5 mm. The magnitude of the electric field between the plates is given as: E = (700 V/(m sec2))*(1-r/Rp)*t 2 where Rp is the radius of the plates...
  47. M

    When is the magnetic flux on a section of a closed surface equal to zero?

    Homework Statement When is the magnetic flux on a section of a closed surface equal to zero? A. When the magnetic field is in the direction opposite that of the section’s area vector. B. When the magnetic field is in the direction of the section’s area vector. C. When the magnetic field...
  48. M

    Which describes the magnetic flux through a section of a loop?

    Homework Statement Which describes the magnetic flux through a section of a loop? A. It is a vector that is directed outward through the section. B. It is a vector that is directed inward through the section. C It is a vector that is tangent to the section. D. It is a scalar...
  49. S

    Help needed in calculating Flux of point source (NucEng)

    Homework Statement A 2 \mug sample of {}^{47}Ca is encased in a lead sphere. What is the photon intensity 5 cm from the source? Use some of the tables in your book to find the required information. Homework Equations Flux/Intensity of photons from a point source...
  50. I

    Exploring Magnetic Flux Tubes: Current, Composition, and Buoyancy

    Does a magnetic flux tube always have a current flowing in it? Where is the current? Electrons on the surface and protons inside? Why are flux tubes magnetically buoyant? That is, why is there a difference in pressure inside and outside the tube. As far as these questions go, is...
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