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. A

    What is the Magnetic Flux through a Loop with Opposite Magnetic Fields?

    Homework Statement Homework Equations Flux = DeltaB * Area The Attempt at a Solution : Since the magnetic fields are going in opposite directions through the loop, I assumed that they would have different signs, so I chose 2.0 T to be positive and 1.0 to be negative, so when calculating the...
  2. E

    Calculating Local Heat Flux in a Pipe: Is h = Nu*(k/x) the Correct Formula?

    I am a little unsure how to get started with a homework question. Essentially, I have to calculate the local heat flux at a distance 1.2m (x) along a pipe. I have the fluid's properties and have calculated the Reynolds number, for which I've determined the flow to be turbulent and therefore do...
  3. F

    Exploring the Effects of Lenz' Law and Magnetic Flux: Is Ferromagnetism the Key?

    Why is it that the induced emf opposes the change in magnetic flux? Is it to follow the law of conservation of energy?
  4. P

    Calculating Mass Flux and Mass Fractions in CO2 and H2 Injection Experiment

    I am working on a experiment that injects CO2 and H2 at a specified mass flux. The mass fraction of each is 0.5. Given the total mass flux of the combined species, how would I find the mass flux of each individual specie? I was thinking it would just be a simple halving since the mass fractions...
  5. H

    Resulting magnetic flux in the core of a transformer

    In a transformer, let's say we have: I1, I2 - currents through the primary and secondary winding V1, V2 - voltages N1, N2 - number of turns F1, F2 - magnetic fluxes through core, produced by the currents I1 and I2 (they are opposing...) R - the reluctance of the core We have V1/V2 = N1/N2...
  6. P

    Neutron flux in coolant and fuel pin in PWR

    In PWR, fast neutron produced from fission in fuel has been moderated into thermal neutron by the a series of collisiion with coolant,i.e. H2O. So the multi-group neutron flux in coolant and fuel pin has much diffenrce, e.g. the relative higher fast neutron in fuel pin and relative higher...
  7. J

    Fixing Error: 10 Particles Got Lost in Fast Reactor Model

    Hi I am trying to run a fast reactor model but I cannot figure out what is happening because I get the error: run terminated because 10 particles got lost. I am using the sdef card (with and without parameters) and the model is not running. Hope you can help me to fix any mistake I did. The...
  8. M

    I Voltage Relationships in Diodes: Exploring Bandgap, Temp & Flux

    Hello, does anybody know if there is a connection between the voltage (work) for the bandgap of a diode, the temperature voltage and the flux voltage?
  9. O

    Derivation of neutron flux equation

    Homework Statement reactor consists of nested spheres (sorry, this is my first time posting): Sphere 1 --> Lead target with radius of R0 (Target-region) Sphere 2 --> Actinide Fuel surrounding lead target; has outer radius of R1 (A-region) Sphere 3 --> Reflector surrounding the fuel with outer...
  10. O

    Neutron Flux in a sub-critical reactor

    Hi everyone, I am supposed to derive the neutron flux equation provided for region A of my reactor. Just wondering if anyone can help me out since I stuck on the derivation for [1/r - 1/R2]; S/4πD aspect is very similar to a solving the constant for a point source spherical reactor Here is my...
  11. moenste

    Speed, force, magnetic flux of an ion?

    Homework Statement The diagram shows a mass spectrometer used for measuring the masses of isotopes. It consists of an ion generator and accelerator, a velocity selector and an ion separator, all in a vacuum. In one experiment, tin ions, each of which carries a charge of +1.6 * 10-19 C, are...
  12. DarkBabylon

    I Determining the flux of an arbitrary vector function

    Hello there. I've been working on trying to re-derive a certain physical formula using vector calculus, and came to a conclusion that in order to derive it, I'll need a way to determine the nature of a certain expression. Specifically: ∯f(v)·da - v={x1,x2,x3,...,xn} and f(v) returns a vector in...
  13. moenste

    Calculate the magnetic flux density

    Homework Statement The magnetic flux density in the vicinity of a large air-cored electromagnet is determined by measuring the induced flow of charge in a small coil as the current in the electromagnet is switched on -- see the diagram below. Calculate the magnetic flux density at the...
  14. moenste

    Magnetic flux density between two wires

    Homework Statement Two identical wires R and S lie parallel in a horizontal plane, their axes being 0.10 m apart. A current of 10 A flows in R in the opposite direction to a current of 30 A in S. Neglecting the effect of the Earth's magnetic flux density calculate the magnitude and state the...
  15. moenste

    Flux density expressions at solenoid centre

    Homework Statement A long air-cored solenoid has two windings wound on top of each other. Each has N turns per metre and resistance R. Deduce expressions for the flux density at the centre of the selenoid when the windings are connected (a) in series, and (b) in parallel, to a battery of EMF E...
  16. Aswin Sasikumar 1729

    How the reluctance in a magnetic circuit depends on flux?

    Since reluctance is equal to length decided by product of permeability and area of cross section,how does reluctance change with flux?
  17. mikemartinlfs

    Four Electric Dipoles = What level of electric flux?

    Homework Statement A circle, centered on the origin, has a radius of 1 mm. At each "pole" (1,0), (0,-1), (-1,0), (0,1) is an electric dipole. The positive charge of +10 microCoulombs is inside the circle, the negative charge of -10 microCoulombs is just outside the circle. What is the...
  18. moenste

    Point between two wires at which the flux density is zero

    Homework Statement A long wire (X) carrying a current of 30 A is placed parallel to, and 3.0 cm away from, a similar wire (Y) carrying a current of 6.0 A. What is the flux density midway between the wires: (a) when the currents are in the same direction, (b) when they are in opposite...
  19. G

    I ITER high neutron flux research?

    I remember reading that in addition to the ITER, that they're also building a facility to study the intense neutron flux that is expected from the reactor in order to study how to better protect materials from the flux. Anyone remember the name of the facility? I'm having trouble finding it.
  20. dykuma

    Surface Brightness at any angle

    Homework Statement Here is a picture of the problem https://www.dropbox.com/s/2bps6ga2o4hjpgw/hw4.png?dl=0 For those who don't want to click the link, basically the problem wants me to calculate the surface brightness of a flat surface at any angle if the source function S = B(T), which is a...
  21. M

    Decoding flux of a vector field

    i was going through Gauss law and the chapter started with flux of a vector field.i understand it mathematically but not physically, i have been reading on the net and most common explanation is that it is the amt of "something"(anything) crossing a given surface.fine till here.then i read that...
  22. Blockade

    Need help in Electric Flux within a cube with Gauss' Law

    Homework Statement I need help in figuring out if I have done this problem correctly. From what I understand ∫E * dA = E*A, where E is the electric field and A is the area of a side. My biggest concern is if I can plug in the length "L" for the "x" and "z" variables within "E = -5x * E0/L i +...
  23. F

    Question about magnet flux and saturation in a motor

    There are 2 primary flux paths in a permanent magnet brushless DC motor. One from the north face of a magnet to the stator through the coils/windings then into the south pole of the adjacent magnet. The other flux path would be from the backside of the magnets through the rotor metal they are...
  24. G

    Calculating Induced EMF in a Bent Loop with Changing Magnetic Field

    Homework Statement The figure below shows a closed loop of wire that consists of a pair of equal semicircles, of radius 7.0 cm, lying in mutually perpendicular planes. The loop was formed by folding a flat circular loop along a diameter until the two halves became perpendicular to each other...
  25. O

    Calculate net charge with nonuniform electric field

    Homework Statement In a cubical volume, 1.05 m on a side, the electric field is given by the formula below, where E0 = 1.25 N/C and a = 1.05 m. = E0(1 + z/a) i + E0(z/a) j The cube has its sides parallel to the coordinate axes, see the figure. Determine the net charge within the cube...
  26. D

    Calculating Net Flux of Glucose Molecules Across a Distance of 1um

    Homework Statement Calculate the net flux (moles m^2- s^-1) of glucose molecules across a distance of 1um if the concentration difference is 100 mols m^3- and the diffusion coefficient for water is 5x10^-10 m^2 s^-1 Homework Equations so i used J=D(c1-c2)/DelaX The Attempt at a Solution I...
  27. M

    Half-Life & Flux: Is Decay Formula Relevant?

    Given an initial mass of some isotope subjected to a constant neutron flux, how fast will the mass drop off? Would not the survival curve look exactly like the curve for radioactive decay? Both cases describe a starting mass subjected to a constant transformative force at a rate that depends...
  28. W

    Axisymmetric FEA model for magnetic flux distortion

    Why do axisymmetric FEA models of magnets and their fields make the field farther from the axis appear denser than it really is when the flux line mode is enabled? I'm using the F.E.M.M. system at the moment. All integrals and graphs give correct values, but the depicted lines of flux appear...
  29. I

    Constant heat flux or constant temperature

    Hey all, first time posting! So I'm having trouble with understanding the differences between the constant heat flux and constant temperature condition when not in a textbook. Some research I have begun working on involves a strip of heat tape sandwiched between two aluminum plates which are...
  30. A

    Cogging torque in coreless axial flux PMG (permanent magnet generator)

    Hi to all. I am simulating a "core less axial flux PMG". This PMG has significant cogging torque. I don't know where this torque comes from because this is a core less generator therefor there is no slot in stator ( no reluctance variation).
  31. A

    Calculating Electric Flux Through a Rectangle with Given Electric Field

    Homework Statement Hello, A 3.60cm x 4.50cm rectangle lies in the xy-plane. What is the electric flux through the rectangle if E=(80.0i + 50k) N/C ?Homework Equations Φ = E * A =EAcos(θ) The Attempt at a Solution My attempt: First convert the rectangle units from cm to m. 4.50cm = 0.045m...
  32. A

    How Do You Calculate Electric Flux Through a Rectangle?

    Hello, The problem: A 3.60cm x 4.50cm rectangle lies in the xy-plane. What is the electric flux through the rectangle if E=(80.0i + 50k) N/C ? My attempt: First convert the rectangle units from cm to m. 4.50cm = 0.045m 3.60cm = 0.036m Find the area of the rectangle. A = 0.036m x 0.045m =...
  33. P

    I Which light do we use to measure flux?

    When we record the flux of a light coming to us from outer space, which light do we use? Do we use visible light or X-ray or UV? Or is it all? Or does it depend on what we're looking at?
  34. J

    How Much Flux Passes Through a Square in a Non-Uniform Electric Field?

    Homework Statement Consider an electric field E = 2x i - 3y j. The coordinate x and y are measured in meters and the electric field is in N/C. What is the magnitude of the flux of this field through a square whose corners are located at (x,y,z) = (0,2,0), (2,2,0), (2,2,2), (0,2,2)? Homework...
  35. J

    Apparent Flux and number of stars

    The stars in our Galaxy have luminosities ranging from $L_{\text{min}}$ to $L_{\text{max}}$. Suppose that the number of stars per unit volume with luminosities in the range of $L$, $L+dL$ is $n(L)dL$. The total number of stars per unit volume if clearly $$n = \int_{L_{min}}^{L_{max}} n(L)dL.$$...
  36. entity314

    Flux Density in Mutual Induction Solenoid with Core

    For a standard solenoid, I've found that B=μnI where μ = permeability of the core (4π×10^-7 for free space) n = number of coils I = current Firstly, is the permeability of soft iron 0.08, as I found? Primarily, however, I'm wanting to know if this still applies for a mutual induction apparatus...
  37. P

    B Influx vs. radius equation, mistake in the dimensions?

    The video:
  38. A

    Position of a coil relative to the magnetic flux

    Does a magnet have to penetrate the plane of a coil in order to generate an emf in the coil? Would an emf be obtained if the coil only passes through the magnetic lines of force, without the magnet crossing the plane of the coil? Thank you.
  39. S

    Does Gravitational Field Flux Cause Gravitational Waves?

    As most of know that magnetic field arises due to change in electric field flux over a surface. In the same way, is there any kind of field arising due to gravitational field flux about a surface ? And if yes then does gravitational field and that field cause each other (in the same way electric...
  40. R

    Magnetic Flux Vectors: How Are Flux Scalar?

    how is flux scalar if the magnetic field and area both are vector quantities?
  41. A

    Flux Pinning in a type 2 SC Using an AC Electromagnet

    When a supercooled type two superconductor is subjected to a static magnetic field, the superconductor pins to the flux of the field (the mixed-state meissner effect is apparent). What happens if it is subjected to a continuously changing magnetic field, assuming the superconductivity takes...
  42. W

    Non-uniform electric field flux through a cube

    Homework Statement A cube side length a=2 has one vertice at the origin of the referencial. an electric field is present described as follows: E(x,y,z)= (2xz) i + (x+2) j + (y(z^2-3) k Find the flux through the cube My cube's front face is at (0 to 2, 0, 0 to 2) Homework Equations flux=∫E.dA...
  43. M

    What does the magnetic flux depend on?

    Homework Statement Does the magnetic flux depend on the shape of the surface or on the enclosed current? Or both or neither? Homework Equations - The Attempt at a Solution I have no clue. I guess a change in the enclosed current is a change in the field and thus a change in the flux, but I...
  44. H

    B Current Flux from Alpha and Beta Radiation

    In a smoke detector there is 1 muCi of Am-241. I'm assuming that means it emits (3.7x10^10)*(1x10^-6)=3.7x10^4 alpha particles per second. Each alpha particle has a charge of 2e, so it seems to me that this stream of particles leaving the Am-241 pellet would carry a current of...
  45. E

    Calculating flux density in an air gap

    I am trying to calculate the flux density of an air gap in an electromagnet. I am following this page that calculates the flux density in a C core with an air gap. My confusion is that I am using 50Hz AC instead of DC I have control over the voltage amplitude since I would be using a variac to...
  46. I

    Electric Flux of Two Hemispheres with different radii

    Homework Statement Two hemispherical surfaces, 1 and 2, of respective radii r1 and r2, are centered at a point charge and are facing each other so that their edges define an annular ring (surface 3), as shown. Homework Equations The field at position r⃗ due to the point charge is: E⃗ (r⃗...
  47. F

    Flux integral over a parabolic cylinder

    Homework Statement Evaluate ##\int\int_S \textbf{F}\cdot\textbf{n} dS ## where ##\textbf{F}=(z^2-x)\textbf{i}-xy\textbf{j}+3z\textbf{k}## and S is the surface region bounded by ##z = 4-y^2, x=0, x=3## and the x-y plane with ##\textbf{n}## directed outward to S. The attempt at a solution I've...
  48. E

    How Magnetic Flux Causes Load on Generators

    this might have been answer before. Question is, what in physics or chemistry creates a load on a generator when the demand increases. For example, If no lights are turned on connected to a generator, it will spin freely. but the more lights are turned on the harder is to spin the generator...
  49. V

    Flux Integral of a Fluid Rotating about an Axis

    Homework Statement We have a fluid with density ρ which is rotating about the z-axis with angular velocity ω. Where should a unit square, call it S, be placed in the yz-plane such that there is zero net amount of fluid flowing through it? Homework Equations...
  50. Drakkith

    Magnetic Flux in a Coaxial Cable

    Let's say we have a coaxial cable with a 2d rectangular surface lying between the inner and outer conductors and running the length of the cable. I'm trying to understand why the magnetic flux through this surface only includes the magnetic field generated by the current flowing through the...
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