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.

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  1. Rahulx084

    Transport Phenomenon: Drag Coefficient & Friction Factor

    My book states that when a flow around object is considered, Non dimensional momentum flux is defined as the drag coefficient In case of flow through tubes it states The non dimensional momentum flux is defined as the friction factor What do these statements mean? What do they practically...
  2. CDL

    Electric Flux through the Face of a Cube

    Homework Statement Griffiths' Introduction to Electrodynamics problem 2.10, Homework Equations Gauss' Law, ##\int_{S} \textbf{E}\cdot \textbf{dS} = \frac{Q_{\text{enc}}}{\epsilon_0}##[/B]The Attempt at a Solution It seems reasonable that the flux through the shaded surface and the front...
  3. Wrichik Basu

    Finding electric flux using Gauss' Law

    Say you have a hollow cylinder, whose one side is open. Now, you pace a positive charge ##Q## at the centre of this open end (such that it is just inside the cylinder). How much should be the flux coming out from the closed end? I just thought of this problem. In order to use Gauss' Law, we...
  4. M

    Flux with an infinitely long surface cutting through a sphere

    Homework Statement Bildschirmfoto 2018-06-19 um 18.50.50.png In the y-z plane there is an infinite long surface with charge density ##\sigma## that slices through a sphere with radius R. Determine the Flux.The Attempt at a Solution I have solved the problem but am stuck at the last part. I used...
  5. Gene Naden

    Flux between two current-carrying wires

    Homework Statement Two long, parallel copper wires of diameter 2.5 mm carry currents of 10 A in opposite directions. Assuming that their central axes are 20 mm apart, calculate the magnetic flux per meter of wire that exists between those axes. What fraction of this flux lies inside the...
  6. L

    I Shock crossing probability for isotropic particle flux

    Hi there, I am currently trying to understand the theoretical frame work of diffusive shock acceleration. I am having trouble understanding a step in the derivation given by drury 1983 (http://www.oa.uj.edu.pl/user/mio/Ast-Wys-En/Literatura/drury.pdf). In the derivation of eq. 2.47 it is stated...
  7. K

    A How is the Neutrino Flux Measured in Accelerator Neutrino Experiments?

    How does the neutrio flux can be measured by a near detector of the accelerator neutrio experiments,such as T2K? As I know neutrino interactions with the matter in the near detector is too low,and so how they can count the neutrino flux by counting the produced particle from the interaction?
  8. DariusP

    I Flux pinning in type 2 superconducotrs

    I'm wondering if for example YBCO superconductor (which is considered type-II superconductor) that exhibits flux pinning effect is a bulk or some substrate with YBCO film on top of it? I always thought that YBCO which exhibits flux pinning is a bulk in all of demonstration videos but it struck...
  9. P

    How do I find out the flux for an air core inductor

    How do I find out gauss from air core inductor 36mohm pumped with ~130amps 9ms long? http://www.parts-express.com/erse-25mh-14-awg-perfect-layer-inductor-crossover-coil--266-380 Greatly appriciated.
  10. A

    Is Solenoid Inductance Proportional to Turns Squared?

    Homework Statement In Solenoid, is emf E= N. d(phi)/dt, or is it simply d(phi)/dt? Some books contain the latter one. It was not a big deal until i gave a thought about it. Since increasing the N, we are actually increasing the value of n, thus increasing B= (mu) .n.I So, by placing N in front...
  11. R

    Electric Flux Through Spherical Surface Centered at Origin

    1. A uniform linear charge density of 4.0 nC/m is distributed along the entire x axis. Consider a spherical (radius = 5.0 cm) surface centered on the origin. Determine the electric flux through this surface. Homework Equations L=2rπ φ=Q/ε λ=Q/L The Attempt at a Solution I found the charge by...
  12. H

    What is the Magnetic Field and Flux at Point O?

    Homework Statement [/B] There is lead XY shaped as straight wire. Next to it, circular lead with radius 0.10 m. They are in the same plane. XY to center of circle, O is 0.20 m. Curent flowing through XY is 15.7 AHomework EquationsThe Attempt at a Solution 1) find magnetic field (B) at O[/B]...
  13. R

    X-ray Flux density and a differential equation for photon scattering

    Homework Statement Consider interactions of a X-ray beam at a depth, x, within a material. The flux density is: density flux = $$\frac{I}{A}$$ where I is the intensity of the beam that cross a unit area A at right angles to the beam. Let dx be a small slice at the depth x and let dI(x) be the...
  14. J

    Electromagnet -- changing flux and a ring

    Homework Statement Homework EquationsThe Attempt at a Solution If an observer stands between A and B then he/she sees current flowing in clockwise direction in A .Now if current in A increases , flux linked with B also increases .From lenz law current should flow in clockwise direction (from...
  15. Pratik007789

    Homework Help: Find the Electric Flux Through a Hole In a Sphere

    Homework Statement [/B] An uncharged nonconductive hollow sphere of radius 10.0 cm surrounds a 20.0 µC charge located at the origin of a cartesian coordinate system. A drill with a radius of 1.00 mm is aligned along the z axis, and a hole is drilled in the sphere. Calculate the electric flux...
  16. C

    How many Amp turns around the Earth for this flux density?

    Someone is asking me how much current in a loop of wire the diameter of the Earth to make the same level of magnetism the Earth has? I hope I am asking this correctly. TIA Clark
  17. A

    Calculating flux with a magnet and a coil

    Homework Statement [/B] Hey, I'm having some difficulties with my physics project and I hoped someone could help me out. We have to calculate the magnetic field, but first we need to know the flux. This is the setup we got: We have to let a magnet fall through a PVC tube. The tube has a coil...
  18. N

    How to calculate magnetic flux from voltage?

    I understand that magnetic flux density is measured in Teslas or Weber’s per square meter and that voltage or emf is measured using faraday’s law of induction which is E= - N dφ/dt Where N= number parallel fields Φ = magnetic flux (Wb) E= emf (V) What I don’t understand is the time function...
  19. O

    Calculating Flux: Homework Statement

    Homework Statement Let S be the surface of a solid R , which lies inside the cylinder: ##x^2+y^2=16## and between the plane where x=0 and z=5 There is also defined a vector field F by: ##\begin{align}F(x,y)=(-x^3i-y^3j+3z^2k)\end{align}## (a) Calculate : $$\iint_{T} F.\hat n\mathrm...
  20. P

    Calculating the flux from a flashlight

    Can you use the flux-luminosity relation, f=L/4*pi*d^2 to calculate the flux of a flashlight at a distance d? As I understand, we can use the relationship given above for a star since we assume that it emits radiation uniformly in all directions, we take the total energy emitted and then divide...
  21. DariusP

    Are flux vortices predictable?

    What I mean by that - is it possible to model a system and somehow obtain them as a result? (in FEMM 4.2 or Comsol for example) Or is their forming still not yet explored enough?
  22. F

    Induced voltage in a coil in a three phase permanent magnet axial flux generator

    I am currently designing a three phase permanent magnet axial flux generator, but have a question regarding the voltage induced in the copper coils. Faraday's law defines this voltage as the number of turns in the coil, times the change in flux (external magnetic field times area of coil) over...
  23. A

    Magnetic flux in a white dwarf

    Homework Statement The sun has a rotational period of 25 days. Finding the rotational period if it can shrink to form a white dwarf (##R_{WD}=10^3Km##). Knowing that the density of magnetic flux of the Sun on the surface is ##1 Gauss##, finding the magnetic flux of the white dwarf. Homework...
  24. T

    Electric flux of a cube due to a point charge

    Homework Statement Homework Equations Gauss's Law The Attempt at a Solution I simply used logic and observed the symmetry of the cube. If the charge is placed on the middle of the cube, the flux would simply be Q/∈0. The face of the cube itself can be split into 4 squares, with the charge at...
  25. mertcan

    Consistency of interpolation in terms of flux at node sides

    Hi, first of all I am aware of the fact that QUICK SCHEME used in computational fluid dynamics has consistent slope at the sides of node elements (for instance at the left side of node 3 in my attachment same slopes exist) as you can see in my picture/attachment. But I must express that I can...
  26. F

    Net electric flux through a cylinder's surface

    Homework Statement Homework Equations ΦE = ∑Q enclosed / ε ∑Q enclosed = λh The Attempt at a Solution ΦE = ∑Q enclosed / ε ∑Q enclosed = λh ΦE = λh / ε
  27. F

    Electric flux through a wedge shaped block

    Homework Statement Homework Equations - The Attempt at a Solution Flux on opposite sides = 0 The answer is (E) , right ?
  28. Cardinalmont

    Inducing EMF Through a Coil: Understanding Flux

    Thank you for reading my post. I can understand why a change in magnetic flux through a conducting surface would induce an emf, but how does this work when inducing an emf through a coil? How does the flux through the empty space between the wires have an effect on the electrons in the wire...
  29. Cardinalmont

    Flux in a Uniform Magnetic Field

    Thank you for reading my post. I was thinking about induced emf and magnetic flux and I realized I have a huge misunderstanding, but I don't know exactly what it is. Below I will list 4 statements which I logically know cannot all be simultaneously true. Can you please tell me which one(s) are...
  30. O

    Thermal neutron flux distribution in reflected core

    Hi, The figure given below was taken from "Nuclear Systems" by TODREAS and KAZIMI. it shows the effect of neutron reflector on the thermal neutron flux radial distribution. Is this correct? Because it does not show the extrapolated distance. It seems to me that the reflector, somehow...
  31. P

    How Do You Calculate Luminous Flux in a Projected Solar Image?

    Homework Statement What diameter will have an image of the Sun (α=32’) projected in the focal plane of a f/7 lens with a focal length of 40 cm? What will be the luminous flux in the image? Homework Equations image diameter = α×f focal ratio = f/D 1 radian = 206265’’ The Attempt at a Solution...
  32. Mayan Fung

    I Flux pinning effect and hysteresis loop

    I am taking an experimental course which requires us to conduct experiments by ourselves. One of the tasks is to demonstrate the flux pinning effect of a type II superconductor YBCO by magnetic levitation. The professor asked me to discuss the effect by using the hysteresis loop (magnetization...
  33. C

    What is the direction of the current in the given image?

    Homework Statement In the picture 20.40, what is the direction of the current induced in the resistor at the instant the switch is closed.[/B]Homework Equations Right hand rules- Point thumb in direction of current and your fingers will curl in direction of magnetic field. Lenz's law. The...
  34. W

    The magnetic flux density at point P between parallel wires

    Homework Statement In the picture at points A and B are two thin parallel wires, where traveling currents are 15 A and 32 A to opposite directions. The distance between wires is 5.3 cm. Point's P distances from A and B are the same. Calculate the magnetic flux density at point P. Homework...
  35. F

    Flux with a non-uniform electric field

    If the electric field is uniform, the electric flux passing through a surface of vector area S is , where E is the electric field (having units of V/m), E is its magnitude, S is the area of the surface, and θ is the angle between the electric field lines and the normal (perpendicular) to S...
  36. SHANKARALINGAM

    Heat Flux Calculation for Titanium & Aluminum

    Hello sir, How to calculate the heat flux of titanium and aluminum?What are the essentials for doing the calculation?We are undertaking a project of multilayer coated cutting tool inserts..So we are in the need of this. Regards, Shankaralingam.
  37. F

    Electric Flux in a Closed Space: Volume, Area & Benefits

    I believe the electric flux within a closed space can be found with the equation phi = Q/ε0. Can this be used for volume and area, or just volume? Also what good does this do. Why would I want to know the electric flux of something?
  38. J

    Integral Neutron Flux: Getting Results with MCNP - Juan Galicia-Aragon

    Hello everyone I am trying to obtain the integral neutron flux based on the results obtained with MCNP (neutron spectrum calculation) for each energy bin (51 neutron energy bins). I have seen in many papers the calculation of the differential neutron flux multiplying the neutron flux results of...
  39. rishi kesh

    Engineering Resultant magnetic flux in a 3-phase induction motor

    Homework Statement I have some attachements below from my textbook. According to it the value of resultant flux is constant in magnitude and 1.5 times the maximum value of flux. But i have a doubt regarding how it is proved. The magnetic flux waveforms are 120° apart from each other and at...
  40. F

    Calculate Electric Flux from Point Charge to Plate:

    Homework Statement A ##10 cm## (on y axis) by ##10 cm## (on z axis) flat plate is located ##5 cm## away (on x axis) from a point charge ##q##. Calculate the electric flux from the point charge to the plate. Can somebody solve it using surface integral using both spherical and cartesian...
  41. LeInvertedPenguine

    I Antiproton flux and cross-sections in antideuterium production

    Hello! I`m currently reading an article about antideuterium production and dark matter detection. The article often uses the term cross-section, like for example: “Assuming an annihilation cross section into a particular Standard Model Channel” and “Probe scattering cross sections through the...
  42. Const@ntine

    Gauss' Law: Charged Rod & Sphere (Electric Flux)

    Homework Statement A charged, straight line/rod of infinite length has a Discrete uniform distribution of charge, has a linear density of λ and is at a distance d from a sphere with a radius of R. Find the entirety of the Electrical Flux that is caused by this charged rod, which passes...
  43. Pushoam

    Flux through an infinite plane due to a point charge

    Homework Statement A point charge q is located a distance d meters from an infinite plane. Determine the electric flux through the plane due to the point charge. [/B] Homework EquationsThe Attempt at a Solution I consider another infinite plane at a distance d in the opposite direction. Now I...
  44. Pushoam

    Elec. flux through the top side of a cube with q at a corner

    Homework Statement Find the electrix flux through the top side of a cube. The cube's corner is on the origin, and is 'a' units on length. The charge 'q' is located at the origin, with the corner of the cube. Homework Equations Gauss's law and symmetry The Attempt at a Solution I take 8 cubes...
  45. Pushoam

    Flux of a point charge through a circle

    Homework Statement Homework EquationsThe Attempt at a Solution I will try to choose the correct option using the common sense instead of solving it. As d decreases, the flux should increase. For R>>d, only option (a) and (d) satisfy this condition. Now, for choosing between (a) and (d)...
  46. R

    Surface Element Conversion for Flux Through Uncapped Cylinder

    Homework Statement In the attached image. Homework Equations Gradient(x, y, z) * <f, g, h> = <fx, gy, hz> The Attempt at a Solution Because the cylinder's not capped, I know that all the flux will be in the radial direction. So, I can find a normal vector by finding the gradient of the...
  47. T

    Wire loop falling out of a magnetic field

    Homework Statement Here is a link to the problem: https://imgur.com/a/0T9sF I am having trouble finding the time it takes the loop to leave the field in part a. Homework Equations ## emf=-\frac{d \Phi}{dt} ## ## \Sigma F=ma=mg-BIl ## ## \frac{dv}{dt}-\gamma v=g ## where ##...
  48. R

    Magnetic field and Poynting Flux in an Inductor

    Hi everyone, Lately I have been studying the Poynting Flux and I am familiar with the classic examples of how it can be used to describe the power being dissipated by a resistor and the energy flowing into a capacitor, but I have never come across a similar analog for how the Poynting flux...
  49. 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...
  50. 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...
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