What is Flux: Definition and 1000 Discussions

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.

View More On Wikipedia.org
Recent contents Top users
  1. guyvsdcsniper

    Magnitude of the flux through a rectangle

    I have attached the work to this problem and although it has different parameters than what I have listed in my post the basis to solving the problem is the same. I am confused on why this rectangle in this problem is considered to b in the j unit vector direction. Is it because its face will...
  2. rudransh verma

    B Understanding Flux: The Measure of Field Lines Passing Through a Surface

    Phi= int(E.da) through a surface S is a measure of “number of field lines” passing through S. I put this in quotes because of course we can only draw a representative sample of field lines. The total number would be infinite. But for a given sampling rate the flux is proportional to the number...
  3. bboo123

    I Exploring the Impact of Dielectrics on Electric Flux Density

    In the 7th edition of the book "Elements of Electromagnetics by Matthew N. O. Sadiku" On page 190 the author goes on to say: "We now consider the case in which the dielectric region contains free charge. If ##\rho_v## is the volume density of free charge, the total volume charge density...
  4. rudransh verma

    Flux of a non-uniform E field through the face of a cube

    Phi = int of (3xi^ + 4j^).vector dA = 3 int of(xdA) Now we put x= 3 and we get at last 36 N m^2/C. I am getting confused why E is a fuction of x. How can that be? How can we represent the E and position x on the same coordinate system. Is it right ? Because we know distance is inversely...
  5. V

    Electric flux through ends of an imaginary cylinder

    When I look at this question, I can see two possible values of electric flux depending on how I take the normal area vector for either ends ##A \text{ and } A^{'}##. What is wrong with my logic below where I am ending up with two possible answers? The book mentions that only ##2E\Delta{S}## is...
  6. rudransh verma

    I What is Electric Flux and How is it Calculated?

    Gauss law relates between E at some point on guassian surface with the net charge enclosed by that surface. Using gauss law is like being able to tell what (ie charge)is inside a gift box by just looking at the wrapper(electric field). There are two types of problem. Sometimes we know the charge...
  7. berserkhealr

    Need help with Axial flux generator

    I am sure axial are used in wind turbines so i will use it as my example. Say you are using the wind turbine to generate power but its getting to windy and you want to slow down the turbine to bring it to a stop. What i want to know is ... If you can cut off the power that's been generated...
  8. Shreya

    Flux density and Divergence of Electric field

    I think Flux density is flux/Volume. Or is it flux/ Area Please be kind to help
  9. Shreya

    Need Help Understanding Electric Flux and Electric Flux Density

    I don't understand the exact meaning of flux. Please be kind to help.
  10. P

    A Representing flux tubes as a pair of level surfaces in R^3

    I am trying to see if Vector fields(I am thinking of electric and magnetic fields) without sources(divergence less) can be represented by a pair of functions f and g such that the level surfaces of the functions represent flux lines. I am trying to solve this problem in ## R^3 ## with a...
  11. adamaero

    Engineering How to calculate rotor flux of the three phase squirrel cage induction motor?

    Three phase squirrel cage induction motor with given parameters (stator winding connected in delta) nominal power: Pn=22.4kW nominal stator voltage: Vsn=230V nominal stator current: Isn=39.5A nominal stator frequency: fsn=60Hz nominal speed: nn=1168min−1 number of pole pairs: 3 stator...
  12. V

    Find the net outward flux through the surface and the charge density

  13. J Silva

    Is the magnetic flux density B constant?

    Summary:: Is the magnetic flux density B constant? Is the magnetic flux constant? I am working on a project design for Uni and I am stuck. In a magnetic circuit is either the magnetic flux or the magnetic flux density B constant? This magnetic circuit has all different cross section areas and...
  14. GhostLoveScore

    Calculating flux density of radio telescope

    Hello I've made a small program that does FFT, Fast Fourier Transform on a signal from radio receiver (RTL SDR), and parabolic antenna. Of course, the output is amplitude depending on frequency. I want to use it to detect and measure 1420MHz radiation from space. But I'm not sure on what's the...
  15. Hamiltonian

    Electric flux through a square lamina

    taking origin at the centre of the square. ##d\phi = \vec E.\vec{da}## $$d\phi = \frac {kqa}{(x^2 + y^2 + a^2)^{3/2}} da$$ $$\phi = \int_{-a/2}^{a/2}\int_{-a/2}^{a/2}\frac{kqa}{(x^2+y^2+a^2)^{3/2}}(dx)(dy)$$ on evaluating this double integral i get $$\phi = (q/\pi{\varepsilon}_0...
  16. B

    Superconductor Flux pinning/Meissner effect with electromagnets?

    I was reading about high temperature superconductors expelling magnetic fields (Meisner effect). I was curious if this only works with permanent magnets or is there similar effects with electromagnets. I assume since the magnetic waves would be similar there would be a similar reaction, but...
  17. A

    I How do I properly plot the solar spectrum and handle the flux of Arcturus?

    I'm trying to plot the solar spectrum (Wavelength versus Flux) from a table of values I'm given. I'm given 3 columns; Solar Flux Arcturus Flux Wavelength Plotting Solar Flux versus Wavelength gives me a graph (below) that is very difficult to resolve. There are 21,000 data points as well. If...
  18. A

    I Coude Spectrograph vs Cassegrain?

    What is Flux Throughput? Explain how there can be a flux throughput advantage in using a coude spectrograph compared to a Cassegrain spectrograph? I'm confused on what this actually means when comparing the two. Is it asking what are the seeing advantages in terms of resolving powers of a...
  19. P

    Rate of heat flux from from hot gas in a pipe to water outside

    I have solved the first 2 parts. For the 3rd part, I have obtained the equation: T(x) - T0 = (T1 - T0)e^(-Φx/fc), where f = fm in the question. How do I obtain that expression for H? Thank you!
  20. Z

    EMF induced by a magnet falling through a coil

    I've been told that if you drop a magnet through a coil the induced emf and flux graphs would look like this: I understand that when the bar magnet is in the middle of the coil the emf induced is zero as flux change in top and bottom is in opposite directions but why is effective flux maximum...
  21. A

    PPMT, Magnetic Flux Switch, electro-permanent magnet generator

    Ok so here is something that made me scratch my head and I still can't come to a final conclusion. The basic idea is seemingly simple. You have permanent magnets attached to a core, the field lines close on both magnets through the core, so far so good. but the core also has electromagnets , put...
  22. H

    Magnetic Flux: Why Does it Stay the Same?

    I calculated in this way as attached and got the correct answer. However I still wonder why the magnetic flux is the same in both coils, or this presumption is not right.
  23. SimoneC618

    Evaluating the results of a Lax-Wendroff scheme on 1-D flux

    Hi everyone, i'm very new to the forum so i hope I've used the correct form to write my question. Anyway, i need some help to evaluate the result of my last analysis: I'm studying the flux flowing inside an ICE aspiration manifold in a very simplified way (1D flux, ideal gas, compressible...
  24. 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?
  25. Y

    How does the saturation flux density affect magnetic field strength?

    So I'm confused what the Saturation Flux Density is referring to. Defintion says it is when you no longer get an increase in H-field when increasing external B-field. So, does the satuation flux mean the core can only create fields UP TO that saturation flux, or that it can make a stronger...
  26. Incnis Mrsi

    I Infrared energy flux from the Moon

    I am interested in energy flux density from the Moon at Earth’s surface, specifically in infrared (albeit most of it comes in infrared anyway). Physics.SX (boyfarrell) gives an estimate 89 mW/m². I doubt it for several reasons. 400 K (as effective mean) on Moon seems to be unrealistically hot...
  27. L

    Magnetic Flux through a Closed Surface and Maxwell's laws

    Hi everyone, I have a question about Maxwell's laws. According to Maxwell the magnetic flux of a magnetic field through a close surface is 0. But his third law says the circuitation of an electric field depends from magnetic flux variation. I can't understand how this can be possible since...
  28. cestlavie

    Magnetic flux given magnetic field and sides (using variables)

    I know the answer is ##ka^3/2##. I got ##ka^2## and I don't know how to get the right answer. I saw an explanation using integrals, but my class is algebra-based. My attempt: ##Flux=ABcos\theta##. I figure ##cos\theta## is 1 becuase the angle between the magnetic field and the normal to the...
  29. E

    Determining the direction of current due to a change in magnetic flux

    This is supposed to be very basic, where the loop is held there is a declining magnetic field in direction (-z), therefore the current is supposed to be clockwise. However in the answers it is said the the current is anti clockwise. That doesn't make sense to me. Is there a mistake in the answers?
  30. L

    Equivalence of various forms of flux linkage

    Hello all, Apologies if this has already been asked before, but I tried researching this question for a while with no results. I was reading Grainger's Power System Analysis' derivation of the inductance of a single wire and got confused by his definition of magnetic flux linkage. He seems to...
  31. AHSAN MUJTABA

    Electrodynamics flux calculation question

    I don't really know how to find it mathematically as I am really confused in finding the normal vector and finding the electric field as well. pls help
  32. T

    MTW Ex 21.23 Poynting Flux Vector 'out of the air'

    ##4\pi\mathcal L = -\mathcal e \frac{\partial A_i }{\partial t} - \phi\mathcal E^i{}_{,i} -\frac{1}{2}N\gamma^{\frac{1}{2}}g_{ij}(\mathcal E^i \mathcal E^j +\mathcal B^i\mathcal B^j) +N^i [ijk]\mathcal E^i\mathcal B^j## MTW (21.100) I'm trying to produce the result required by the problem...
  33. bln1230

    Help me find the electric field vector

    I have these equations in my book, but I don't know how I can use them in this problem Electric field of a plane has surface electric density σ: E = σ/2εε₀ Ostrogradski - Gauss theorem: Φ₀ = integral DdS Can someone help me :((
  34. Jy158654

    Calculation of Change in Magnetic Flux Linkage of a moving wire

    Can anyone explain the above answer to me? What does the "change in area" mean?
  35. AN630078

    Solar Panels and Solar Radiation Flux Density Help - Very Confused

    Question 1; a) P=E/t E=5.796*10^7 J energy produced per day during the summer However, I am not certain how to calculate the time period, since although this concerns the energy produced per day, the sun does not shine for the entire duration of this 24 hour period. Also, I am unsure of the...
  36. lelouch_v1

    Magnetic Flux outside of a long solenoid

    I have been reading Griffith's Introduction to Electodynamics and i am currently at the chapter about magnetostatics. There is an example about a long solenoid with n units per length and radius R that shows a way of finding the magnetic vector potential. The magnetic field inside the solenoid...
  37. Kaguro

    Flux in a rotated cylindrical coordinate system

    ##\vec F= 2x^2y \hat i - y^2 \hat j + 4xz^2 \hat k ## ## \Rightarrow \vec \nabla \cdot \vec F= 4xy-2y+8xz## Let's shift to a rotated cylindrical system with axis on x axis: ##x \to h, y \to \rho cos \phi, z \to \rho sin \phi ## Then our flux, as given by the Divergence theorem is the volume...
  38. jaumzaum

    Exploring the Factors Affecting Leakage Flux in Transformers

    Hi! I was wondering why even a real transformer has a very low leakage flux, what makes it be this way way? Is it the ferromagnetic material? If so, why? If the core was made of completely vacuum would the leakage be 100%?
  39. L

    Question：What is the difference between flux and current?

    Guys,I need to calculate the flux and current of neutron by MCNP.So what's the difference between them ,and How to calculate them? Any ideas?
  40. Frigus

    Why is the net flux through a closed surface equal to zero?

    Suppose we have placed a cube in field which varies linearly with z axis so electric field magnitude on coordinates of face ABCD is clearly more than face EFGH and we know area of both faces are equal, So if we calculate flux then it would be non zero but it contradicts with the fact that...
  41. E

    Flux Terminology: Scalar Flux vs. Flux Density in Different Contexts

    Forgive me if a similar thread has been posted before... I was doing some questions and I just noticed an apparent discrepancy in how the term "flux" is thrown around. In the context of surface integrals, the scalar result is usually termed the flux whilst the vector field is termed the flux...
  42. astroYEEET

    Interaction of an astronaut with the CMB flux

    From the density and the mass we can find the volume using d=m/v <=> v=0.06 m^3. Since we consider the astronaut a sphere we find his radius using V(sphere)=4/3*π*R^3 =>R=0.242m. Now we can calculate the surface area with the formula A=4πR^2=0.735m^2. The energy absorbed will be i suppose equal...
  43. G

    Electric field and electric potential exercise

    a) \vec{F}=\vec{E}\cdot q \phi =\oint \vec{E}d\vec{S}=\oint \vec{E}d\vec{S}=\underbrace{\oint \vec{E}d\vec{S}}_{\textrm{FACES } \perp}+\underbrace{\oint \vec{E}d\vec{S}}_{\textrm{FACES } \parallel}=0+\oint EdS\cdot \underbrace{\cos 0}_1= E2S \dfrac{Q_{enc}}{\varepsilon_0}=\phi \left...
  44. Kharrid

    Induced EMF in a moving Loop Conductor

    I am having trouble figuring out if the circular loop has an induced current. One explanation is ∫ E ds = -d Φ / dt. Since flux = B ⋅ A, a change in the magnetic field would require a change in the magnetic field, a change in the area, or change in direction of either vector. Since none of...
  45. P

    Electrix flux through a hemisphere

    My attempt is for part a a. The electric field is into the base of the hemisphere and the area vector is coming out of the base Θ=180 Area of base of the hemisphere is = π * r^2; Hence the electric flux ∅ = ∫ E.dA; ∅ = E*π*(0.0568^2)*cos(180) = -2.5*π*0.00322= - 0.0253N.m2/C; b. For the part...
  46. 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...
  47. Zack K

    Verifying the flux transport theorem

    Let ##S_t## be a uniformly expanding hemisphere described by ##x^2+y^2+z^2=(vt)^2, (z\ge0)## I assume by verify they just want me to calculate this for the surface. I guess that ##\textbf{v}=(x/t,y/t,z/t)## because ##v=\frac{\sqrt{x^2+y^2+z^2}}{t}##. The three terms in the parentheses evaluate...
  48. T

    I Alternate Maxwell-Faraday Equation for Superconductive Flux Pinning?

    In order to flux-pin a piece of type-II superconductor in a magnetic field, the piece of superconductor is held in place within a magnetic field and supercooled. Let's say that Bp is the B-field within the superconductor as it is being pinned. After pinning has been carried out, is it correct...
  49. A

    When is the flux through a coil from a bar magnet zero?

    Suppose I have a finite sized cylindrical bar magnet of radius $a$ and length $b$. It is coaxial with the $x$ axis and moving from $-\infty$ to $\infty.$ A circular closed wire of radius $r>a$ is in the $y-z$ plane with center at the origin. When the bar center of the bar magnet passes through...
  50. LordGfcd

    What is the continuity condition for the heat flux through a boundary?

    Assume there is a boundary separates two medium with different heat conductivity [κ][/1] and [κ][/2]. In one medium, the temperature distribution is [T][/1](r,θ,φ) and on the other medium is [T][/2](r,θ,φ). What is the relationship between [T][/1] and [T][/2] ? Is it - [κ][/1]grad [T][/1]=-...
Back
Top