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. Pushoam

    Solving Flux of Molecules Problem

    Homework Statement Derive the flux of molecules i.e. no. of molecules striking a surface per unit area per unit time. Homework EquationsThe Attempt at a Solution [/B] Let's say that there are n molecules per unit volume. The no. of molecules which will touch the surface in the +ve x...
  2. yecko

    Understanding Flux of Vector Fields: Equations, Solutions, and Common Mistakes

    Homework Statement Example 2:[/B] Homework Equations Flux=integrate -Pgx-Qgy+R of the proj. area on xy plane for z=g(x,y) The Attempt at a Solution Why do my attempt is wrong? The example is using the foundational formula while I use the stock formula from the book, why is there a negative...
  3. D

    Magnetic flux in tap changing transformers

    Hi guys, Non engineer here trying to understand an engineering principle. I think I must be going wrong somewhere in my thought process. 1. Faraday tells us that the EMF generated in the secondary of a transformer is equal to the change in magnetic flux divided by the change in time. 2. The...
  4. A

    MCNPX Mesh Tally Problem: Offset of proton flux at surfaces

    Dear all, we are using MCNPX for the simulation of proton beam interactions at our proton therapy facility. But now we found a very strange behavior within a RMESH1:h flux tally: In an even very simple geometry we see a constriction or rather offset of the Proton flux at surfaces (surface 1118...
  5. O

    Why is differential neutron flux commonly used in nuclear reactors?

    Hi, Below are the neutron flux spectra of a nuclear reactor. In the first spectrum, y-axis is differential flux and in the second spectrum, y-axis is flux (created by multiplying differential flux by energy in MeV). As far as I have seen so far, differential flux is used commonly. I am just...
  6. Y

    Why does the magnetic flux in a solenoid depend on the number of loops?

    In a solenoid of N loops and uniform magnetic field B, the magnetic flux is B*N*A, where A represents the area surrounded by each loop. I see that the N comes from the fact that you have one A for each turn, and you have N turns, so the total "area" is NA, but why do we use this? Why isn't...
  7. M

    Flux induced in a circular loop

    Homework Statement I have a circular loop with a radius of 1 m. The center of the loop is located 2 m away from a infinitely long current carrying wire, with ac current I. Find the flux in the circular loop Homework Equations Φ = ∫ B ds The Attempt at a Solution I've found a lot of examples...
  8. Y

    Why do charges outside surface create no net flux?

    Why do charges outside the surface contribute 0 net flux? The book I'm reading says it's because the flux entering the surface cancels out with the flux exiting the surface. But that means E dot Area must be exactly the same magnitude when entering and exiting to cancel out. But we know E-field...
  9. T

    Understanding Gauss' law: diff b/w E and D flux?

    I noticed the other day something odd in how we use Electric and Magnetic flux. The definitions I refer to are magnetic flux density (B), magnetic flux intensity (H), electric displacement field (D) or Electric field density (D) and electric field (E): B = μH ΦB = B*Area & D = εE ΦE = E*Area...
  10. Physics Dad

    Astrophysics Problem - Effects of cloud on flux density

    Hi, I am attempting the following question: 1. Homework Statement If the extinction in the infrared K-band (filter central wavelength = 2.13 micrometres) is 10 times less than it is in the optical V-band (filter central wavelength = 550 nanometres), what affect would a cloud of Av = 3 have on...
  11. P

    Behavior of inductors -- Why flux linkage does not change instantaneously?

    Why is it that the flux linkage does not change instantaneously ? is it some property of magnetic fields?
  12. T

    Temperature and magnetic flux density

    Hello all; I am new in this forum, currently in High School. For some time now, I have been looking online for a relationship between temperature and magnetic flux density of a ferromagnet; below the Curie point. However, I can't seem to find any relationship or formula. Do any of you know...
  13. Marcin H

    Flux Integral: How to find ds for line integrals in general

    Homework Statement Homework Equations flux = int(b (dot) ds) The Attempt at a Solution I just wanted clarification on finding ds. I understand why ds is in the positive yhat direction (just do rhr) but I don't understand where the dxdz come from. How do we find ds in general?
  14. A

    Negative Sensible Heat Flux at Earth's Surface

    I'm a bit confused as to how to imagine a negative sensible heat flux near the Earth's surface. Negative means that sensible heat is moving towards the surface. My book states that that would mainly occur at nighttime. During day there is a positive sensible heat flux and sensible heat moves...
  15. Marcin H

    What is the relationship between ds vector and theta in flux integrals?

    Homework Statement Part b and e. Homework Equations Flux = surface integral of B (dot) ds The Attempt at a Solution I just want to make sure that I have a good understanding of ds. ds is just the direction of the vector that is normal to our area that we are finding our flux throuhg...
  16. mertcan

    Magnetic flux is the same if we apply the Biot Savart?

    Hi, initially I am aware that magnetic flux is conserved due to divergence of magnetic field is zero and for long solenoid, magnetic field inside is uniform. So magnetic field intensity (B) at point P,Q,S, T,R,U(in the attachment) must be same. But my question is : can we obtain the same...
  17. D

    Electric Flux through Cubical Surface Enclosing Sphere

    Homework Statement A uniform charge density of 700 nC/m3 is distributed throughout a spherical volume of radius 6.00 cm. Consider a cubical Gaussian surface with its center at the center of the sphere. [reference picture] What is the electric flux through this cubical surface if its edge...
  18. A

    Unit Conversion of Flux: Jansky to Erg/s/cm²/Å - Simplified Guide

    Hello, I am struggling a little bit with what I believe to be a simple unit conversion. For this problem, I have many fluxes given in units of Janskys. I would like to convert them from their original units of Jy = 10-23 erg s-1 cm-2 Hz-1 to units of erg s-1 cm-2 Angstrom-1 When I try to do...
  19. T

    Magnetic flux and inductance?

    If a current flows in a straight wire, a certain amount of magnetic flux will be generated around it. Now suppose I put an iron tube around the wire (but don't change the current). I know the inductance will increase, but is that because more total flux is now being generated, or is the total...
  20. C

    A Neutrino flux at event horizon

    Hi, Assuming an average Neutrino mass of 2.0 Electron volts how much mass will a black hole with an event horizon the size of the one at the center of our galaxy accrete in a year? I've seen estimates of how many Neutrinos pass through our bodies each second and it seems like the mas would...
  21. R

    Electric Flux Equation for Rotating Loop?

    Homework Statement A circular loop with radius r is rotating with constant angular velocity w in a uniform electric field with magnitude E. The axis of rotation is perpendicular to the electric field direction and is along the diameter of the loop.Initially, the electric flux through the loop...
  22. M

    Flux Through A Sphere Surrounding A Parallelepiped

    Homework Statement The rectangular parallelepiped with sides ## a > b > c ## is filled with charge of constant density ## \rho ##. A sphere of radius ## 2a ## is constructed with its center at the origin. Find the flux through the surface of this sphere Homework Equations $$ \oint E \cdot...
  23. P

    What Is the Volume Flux for a Hydraulic Jump?

    Homework Statement Problem is given in this image, https://gyazo.com/454370ff9549dcd7c53604ebfe5df105 Homework Equations Continuity or conservation of mass equation: \frac{\partial u}{\partial x} + \frac{\partial w}{\partial z} = 0 Where u is the horizontal velocity and w is the vertical...
  24. V

    How calculate the Heat flux requiered to evaporate sub cool water

    Homework Statement I was trying to validate a calculation I didusing ANSYS fluent, it's about a flow of water that enters a tube, the tube is 16m long and is being heated with a Heat Flux of q'=1077328,47 [W/m^2], now after the simulation runs and I check the results I find out that the steam...
  25. F

    Induction motor - calculating rotor flux angle

    Hello. I'm trying to write my own soft for Field Oriented Control of induction motor. I have finished hardware - 3ph 3kW inverter, controlled by STM32F4, and V/F open loop algorithm to control ACIM - it works. Now I'm trying to implement FOC algorithm. As we know we need to do Clark&Park...
  26. B

    Magnetic Flux Questions from Japanese University Exam Papers

    Hello everyone, This is my first post here Firstly, I'd like to start by saying that it's my best intention to follow the rules on this forum. Therefore, if I've posted this in the wrong section please forgive me, I will try and learn the ropes quickly. One of my students has given me some...
  27. V

    Finding the magnetic flux from a 3 Dimensional Shape

    Homework Statement In Fig. 32-9 there is a + x-directed uniform magnetic field of 0.2 T filling the space. Find the magnetic flux through each face of the box shown. Homework Equations ΦM = B ⊥ A = BA cos θ The Attempt at a Solution My attempt is attached to this post. How do I determine which...
  28. G

    I How does flux density scale with redshift?

    I'm not sure I understand how to correctly scale flux density with redshift. That is, if I observe say 10 Jy at my observing frequency coming from a source at z = 0.3, how can I estimate the flux density I would expect from the same source at z=2? From what I understand, the final scaling is...
  29. W

    Calculating electric flux when given a charge (Gauss)

    Homework Statement A charge Q=5.14 nC is located at the center is located at the center of a Gaussian sphere of radius R=10.0 cm . The sphere lies within a uniform upward electric field E=2100 NC The net outward electric flux through the sphere is What? Second problem (bonus round!) A...
  30. S

    Magnetic Flux vs Temperature Relationship in Ferromagnets

    Hi everyone, I have recently done an experiment testing the effect of temperature on magnetism through measurement of magnetic flux at a constant distance away from the measuring device. I used a range of 0-90 C for neodymium and bar magnets, and found a reasonably linear trend, with a similar...
  31. C

    Is a flux density of 227.6 T realistic for a 5cm bar magnet?

    Flux density of a magnet is about how many T? In an experiment, I obtained the number 227.6 T. Is this a sensible value for a small (5cm long) bar magnet? Thank you~
  32. L

    Magnetic Flux through conductor coil

    Homework Statement Consider a conductor loop which rotates about the y-axis with angular velocity w. The positive y-axis is directed into the paper, the x-axis to the right and the z-axis upwards. There is an inhomogeneous magnetic field along the positive x-axis. Calculate the magnetic flux...
  33. D

    One-dimensional integration - flux

    <Moderator's note: Moved from a technical forum and thus no template.> Calculate flux of the vector field $$F=(-y, x, z^2)$$ through the tetraeder $$T(ABCD)$$ with the corner points $$A= (\frac{3}{2}, 0, 0), B= (0, \frac{\sqrt 3}{2},0), C = (0, -\frac{\sqrt 3}{2},0), D = (\frac{1}{2},0 , \sqrt...
  34. D

    A Determine the flux of the vector field trough the surface

    From my drawings it seems to be half of hemisphere. Am I right? How can I solve this task? Determine the flux of the vector field $$ f=(x,(z+y)e^x,-xz^2)^T$$ through the surface $Q(u,w)$, which is defined in the follwoing way: 1) the two boundaries are given by $$\delta...
  35. Y

    What force does the current carrying coil feel?

    Homework Statement What direction does the force that the current carrying coil feel point to when a magnetic field is turned on? A magnetic field is turned on and points from bottom to top and passes through a current carrying coil that has current passing through it CCW. Here is a diagram...
  36. T

    Relation between current and flux

    So I learned that voltage/emf is proportional to the negative change in flux so the graph of the voltage is the negative derivative of the flux graph. What is the relation between flux and current. In a motor, a change in flux induces a current that creates an opposing magnetic field, and...
  37. Noaha

    Rotor and stator flux in 3 phase Induction motor

    The rotor and stator flux speed are stationary with respect to each other in 3 phase induction motor. What will happen if there is relative speed between them? How these two fluxes interact with each other to develop a torque?
  38. T

    Calculating the mutual coupling coefficient of E cores

    Hi, I can't find my inductance calculations book. Say that you were considering magnetic flux linkage more from a geometric perspective: -Does the mutual coupling coefficient for a series of coils all on the same steel core add up to a maximum total of ~1? Because I tried simulating a three...
  39. N

    Experiment - Flux, Irradiance, wavelength from Temperature

    In my experimental setup I have a purpose built small aluminium tube that has a black layer on the inside to mimic a blackbody. The tube is heated so the inside emits as a blackbody. A separate temperature sensor attached to the tube gives the temperature of the tube. I have a thermopile...
  40. N

    Wavelengths, Flux Density, Irradiance from a temperature measurement

    Homework Statement In my experimental setup I have a purpose built small aluminium tube that has a black layer on the inside to mimic a blackbody. The tube is heated so the inside emits as a blackbody. A separate temperature sensor attached to the tube gives the temperature of the tube. I...
  41. T

    How does mutual inductive coupling affect transformer operation?

    Hi, I have a couple of questions regarding re-wiring a three phase transformer. Say you have a three phase TX with a ratio of 415:22 and you want to use it as a single phase step-up TX (excite it with a variac or something), this is a thought-experiment. If you excited only the middle leg of...
  42. M

    Flux dependant upon the number of turns?

    https://atarnotes.com/forum/index.php?topic=144870.msg953546#msg953546 http://i.imgur.com/XtCj6OP.png (worked solution on left and plain answer on right; they aren't the same and neither take into account the number of turns, which adds to the confusion) Is the book's answer correct? Doesn't...
  43. Sunbodi

    What is the Electric Flux through a Net in a Uniform Electric Field?

    Homework Statement [/B] A butterfly net hangs from a circular loop of diameter 400 mm . You hold the loop horizontally in a region where the electric field is 150 N/C downward, as shown in (Figure 1) . What is the electric flux through the net? Homework Equations k = 9E9 N E = kq/r2 Flux = Q...
  44. AlphaLearner

    Electric Flux Questions (about the definition)

    I can say that Electric Flux is Electric field passing per unit area perpendicular to electric field lines. But the formula came up as Φ = ∫ E⋅dA. Well, take the case of pressure! That is force acting per unit area perpendicular to direction of force. But it's formula came up as P = F/A. Now my...
  45. Asmaa Mohammad

    The magnetic flux and the induce emf in the dynamo.

    Homework Statement Multiple-choice question: Homework EquationsThe Attempt at a Solution I know that the induced emf is maximum when the coil is parallel to the direction of the magnetic flux, so I should choose either B or C, and I have read the the rate by which the coil cut the magnetic...
  46. Pushoam

    Magnetic flux rule for calculating motional EMF

    Homework Statement Griffith ( Introduction to electrodynamics , 3 ed.) says in Problem 7.9: An infinite number of different surfaces can be fit to a given boundary line, and yet, in defining the magnetic flux through a loop, Φ = ∫B.da, I never specified the particular surface to be used...
  47. Baptiste Debes

    Magnetic flux through a rotating bar

    Hello everyone, My question is between theorie and practical (so I'm still wondering if it's the right place). I'm reading Serway and Jewett. There's an example about the magnetic flux through a rotating bar and so and induced emf. I understand this emf will be equal to the the opposite of the...
  48. W

    Why Is It Sin Theta Instead of Cos Theta in Magnetic Flux Calculation?

    Homework Statement I had know that for finding magnetic flux is NBA cos theta. The answer is C though, so why is it sin theta instead of cos theta? I wonder Homework Equations BA cos theta NBA cos theta[/B] The Attempt at a Solution
  49. T

    Magnetic alignment of steel question

    Hi, I have a question about steel, for instance, silicon steel used in magnetic cores. I was wondering about how Iron magnetises: can you align the grains/domains and heat treat it [or anything], so that it responds differently to flux one way then the other direction? For example, say you...
  50. P

    Why Is Magnetic Flux Calculated Using the Solenoid's Area Instead of the Loop's?

    Homework Statement Question asks for the flux through the loop when the loop is both perpendicular and at an angle to the solenoid. solenoid diameter = 2.2 cm loop diameter = 6.8 cm B inside solenoid = 0.22 T Homework Equations ∫B⋅dA = Φ_B The Attempt at a Solution B is constant so can...
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