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. gracy

    Electric flux through open surface

    I know in such type of questions we should try to enclose the charge completely and symmetrically by as many bodies requires as that of the given body. Let's say if Charge Q is kept at the mouth centre of a hemisphere .Here a hemisphere is given so we know if another hemisphere is placed below...
  2. J

    Finding flux through surface where E field is function of x

    Homework Statement In a region of space there is an electric field E(vector E) that is in the x-direction and that has magnitude E=(663 N/(C*m))x Find flux for this field through a square in xy plane at z=0 and with side length 0.330m . One side of the square is along the +x-axis and another...
  3. xSpartanCx

    Flux through a sphere due to a charge outside of it

    Homework Statement A point charge of +5.00 μC is located on the x-axis at x= 5.00 m , next to a spherical surface of radius x= 4.00 m centered at the origin. [/B] According to Gauss's law, the net flux through the sphere is zero because it contains no charge. Yet the field due to the external...
  4. yango_17

    Manually integrating to find flux through hemisphere

    Homework Statement Basically, I am being asked to calculate the electric flux through the top of a hemisphere centered on the z-axis using "brute force integration" of the surface area. Homework Equations Gauss' Law The Attempt at a Solution Using intuition and Gauss' law, I know that the...
  5. K

    Charge Distribution in Nonconducting Shell System

    Homework Statement A charged particle is suspended at the center of two concentric spherical shells that are very thin and made of nonconducting material. Figure (a) shows a cross section. Figure (b) gives the net flux Φ through a Gaussian sphere centered on the particle, as a function of the...
  6. gracy

    Electric flux calculation in case of a cylinder

    Homework Statement an electric field is uniform,and in the positive x direction for positive x,and uniform with the same magnitude but in the negative x direction for negative x.it is given that vector E=200 I^ (N/C) for x>0 and vector E= -200 (N/C) for x<0 .A right circular cylinder of length...
  7. gracy

    Electric flux calculatio in case of a cube

    Homework Statement the electric field components in the figure below are Ex=800 x^2 N/C ,Ey=Ez=0 calculate the flux through the cube a=assume 0.1 m Homework Equations The Attempt at a Solution here flux of cube =flux through ABCD =800a^2 i^.a^2 i^...
  8. nothing909

    Calculating the Flux: Understanding Mean Radius & Circumference

    Question: The magnetic circuit shown (in the pictures) is constructed with a semi-circular piece of metal and a metal bar. The c.s.a of the metal parts is 10mmx10mm. The coil has 500 turns and a resistance of 10Ω. μr of metal parts = 1500. μo = 4π x 10-7 My attempt: I completely understand...
  9. P

    How Does Electric Flux Calculation Apply to Complex Fields and Geometries?

    Homework Statement 1) A large cube has its bottom face on the x-z plane and its back face on the x-y plane. The corners on the x-axis are at (3.39 m,0,0) and (12.3 m,0,0). The cube is immersed in an electric field pointing in the positive x-direction, and given by: E = (91.2x^2 - 2.9)i, x is...
  10. cnh1995

    How does field rheostat resistance affect the speed of a DC shunt motor?

    Suppose a motor is run at 1500 rpm and field rheostat is at minimum position (say 10Ω). Then the field rheostat resistance is increased to 100Ω and the speed obtained is 1700 rpm. Now the motor is shut down and started again. Will it now run at 1700 rpm? My logic: No it won't, because: the...
  11. Salvador

    Exploring Magnetic Flux Path in Coil Wound on a Solenoid

    Hi, I was wondering about a simple example.take a coil wound on a solenoid, one side of the solenoid core is permanently attached to a permanent magnet S pole, the other end of the solenoid core is not attached to any magnet. Now I take another magnet turn it with the N pole facing the solenoid...
  12. E

    Solving a DC Current Magnetic Flux Problem

    Homework Statement A direct current i=10 A flows in a long straight round conductor.Find the magnetic flux through half of the wire's cross section per one metre of it's length. Homework EquationsThe Attempt at a Solution I have spent quite a while thinking on this problem but I can't think of...
  13. Vinay080

    Newton's view on Line generation

    The following passage has been extracted from the John Stewart's English translated version of the "Sir Issac Newton's two Treatises: Of the Quadrature of Curves, and Analysis by equations of an infinite number of terms" http://archive.org/details/sirisaacNewtons00stewgoog: Here Newton...
  14. F

    Calculate flux from a radiating disk

    Homework Statement Suppose you have a disk of radius r at x=y=z=0 with its normal pointing up along the z-axis. The disk radiates with specific intensity I(\theta) from its upper surface. Imagine the observer plane is at z=Z, where Z is much greater than r. Let I(\theta) = I = constant...
  15. R

    Simulator for Radiometry:Radiosity/Radiant Flux density?

    Hey All, I was wondering if anyone knows of any good simulation software packages that can do quantitative radiometry. I'm thinking COMSOL may have a radiometry suite, but I'm not very familiar with the software or package offerings. Basically, I'm trying to optimize the placement of hundreds...
  16. A

    Heat flux trough non-homogeneous bar

    When you have the both sides of a non-homogeneous bar with thermal conductivities k1 and k2 in contact to 2 different temperatures, can you consider it the same as if there was some flux going through a homogeneous bar with the weighted mean of k1 and k2 as the conductivity?
  17. ulfurh

    Help with electromagnetic musical instrument design

    Hello everyone, For the past 4 years I have been working on a new type of musical instrument that fuses together elements from electronic music into the acoustic realm. The instrument consists of 26 strings inside a wooden enclosure that are actuated (or "bowed") by the use of electromagnets...
  18. Salvador

    Axial Flux Generator: Connecting Coils in Series for Single Phase Output

    Hi, in an axial flux generator if the flux passing through any of the coils at any given time constant is in the same direction , can all the separate coils be connected in series as to create a single phase output? in permanent magnet rotor this would mean that the rotor disc facing from one...
  19. Navin A S

    Wireless Power Transfer: Magnetic Flux?

    If a conductor carrying current has magnetic flux around it,why not a carrier wave that carries current in case of wireless power transfer has a magnetic flux around it?
  20. Zahid Iftikhar

    Why is EMF generated by changing magnetic flux?

    I am fixed to find out the reason what makes the charges get separated in conductor causing an emf leading to induced current. A very good reason exists for motional emf. It can be explained with the help of F=qvBsinΘ.
  21. U

    Heat equation given constant surface heat flux

    How would I go about finding temperature distribution in a thin square plate during the the first few milliseconds (or actually a fraction of a millisecond) after t=0s. Initial temperature distribution throughout the plate is known, there is heat flux to one side = Qinj, while heat flux from all...
  22. E

    Calculate flux in a ferrite bead on a wire

    Suppose that a ferrite bead is put around a cable where a constant current I flows, just like in this image. The coordinate system has the z axis along the cable. Let's evaluate the current through the (x,y) plane: according to the Ampère's law, the only magnetic field component generated by...
  23. L

    Lenz's Law Q: Clockwise or Counterclockwise?

    Homework Statement A long, straight wire lies on a table and carries a current I. As the drawing shows, a small circular loop of wire is pushed across the top of the table from position 1 to position 2. Determine the direction of the induced current, clockwise or counterclockwise, as the loop...
  24. M

    Is there a resultant holding torque in the rotor?

    Hi, sorry for the title. I struggled to accurately describe my question in a short sentence. I'm trying to understand if there would be a holding torque or not in the following scenario. I'm referring to a motor which has a central stator and two permanent magnet rotor plates on either side...
  25. Z

    Flux is not controllable in Direct Torque Control of IM

    Hi all, I was trying to simulate a direct torque and flux controlled induction motor in simulink. Even though I've managed to control torque within the band, i can't seem to be able to control the flux. It stays for a while within its hysteresis band and escapes after about 0.1 sec and keeps on...
  26. Kerrigoth

    Are induced currents created by motion or change in flux?

    The book I am working through is beginning to dive into induced currents and Lenz's Law. When a conductor is moving perpendicular to a magnetic field, the charge carriers inside will experience a magnetic force; This causes the charges to move. Eventually, the electric field from the charge...
  27. J

    Why Is the Cross Sectional Area of a Coil Used in Calculating Flux Linkage?

    Flux linkage in a wire coil is given by BANcos(theta) with B being flux density, N being the number of turns in a coil and A being the cross sectional area of the coil and theta being the angle between the normal to the plane of the coil and the magnetic field. Is anybody able to explain why it...
  28. Cookiey

    Induced Emf due to changing magnetic flux

    If we have a conducting loop, and a magnet (say North pole first) is pushed into it; that induces and emf and hence a current in the coil due to the changing magnetic flux, right? According to Lenz' law, the direction of the current is such that it opposes the change. So from the side the magnet...
  29. R

    How to find the magnetic flux of this magnet?

    I am looking to find the magnetic flux of a cylindrical magnet as it passes through a coil. I am aware of the complexity of magnetism, however, i am only looking for a conservative approximation of the magnetic flux. I found the formula ΦB = B · A, but is my understanding that the magnetic...
  30. P

    Design 1.5 A Solenoid & Charge 1.5 V Battery

    Hey All, I'm trying to design a solenoid that would generate about minimum 1.6 A of current in order for me to charge up a 1.5 A 1.5 V battery. I already designed one which is about 10CM in length and unknown number of turns (as I used a drill to wind the coils around it. so I would guess its...
  31. seo_andromeda

    Transforming FERMI SMARTS data from magnitude to flux

    I'm using data from the FERMI SMARTS website, which gives the emissions of blazers. The data has been calibrated using differential photometry (dividing by the average magnitude of a number of reference stars.) "The raw photometry of comparison stars in the field of the blazar was calibrated...
  32. R

    How do you calculate magnetic flux for maxwells equation?

    Flux is defined as (Area Perpendicular to field) x (magnetic field). If a magnet is traveling through a coil of wires. How do you figure out the area perp to the field?
  33. G

    Flux linkage in inductance calculation for single wire.

    Hello. Maybe this is the one of the most typical example in Electromagnetism textbook. There is a single round wire carrying current I (in D.C) with radius of R and length is infinity. From Ampere's law, the B field inside the wire is B = μIρ/2πR2 aθ where ρ is radial distance from...
  34. N

    How Does Coil Orientation Affect Mutual Inductance Calculation?

    Homework Statement A rectangular coil is composed of 150 turns of a filamentary conductor. Find the mutual inductance in free space between this coil and an infinite straight filament on the z axis if the four corners of the coil are located at Homework Equations B = (phi-hat) μoI/2πr dS =...
  35. S

    Equation for flux in reflected slab reactor

    So, I've been at this for a while now. I am using my textbook (Introduction to NE, Lamarsh) and I cannot find a solution to calculate the thermal and fast fluxes in the reflector of a critical slab reactor. I have only been able to find solutions for the spherical shape, even online. As I...
  36. Nile Anderson

    How does one calculate the flux density B at end of solenoid?

    Homework Statement I came across a recent problem that asked me to calculate the flux density at the end of a solenoid. I was given the current 3 A , the number of turns per unit length , 12 cm-1 and the using the permeability of free space as 4π × 10^-7 Homework Equations The equation I used...
  37. magnetpedro

    Magnetic Flux Through a Tilted Medium

    Imagine a ferromagnetic medium shaped as a cylinder (a ferromagnetic fiber) with a magnetic relative permeability of μr, tilted with an angle a, as shown in the picture. I would like to prove analytically that the sum of the inductances measured along the x-axis (angle is a) and y-axis...
  38. W

    Momentum Flux Correction Factor

    I'm a bit confused about the momentum flux correction factor which shows up in the conservation of linear momentum equation for fluids. What I am confused about is when the factor is used. The linear momentum equation has its general form and then a simplified form where the momentum flux...
  39. J

    Faraday disk/ how is the magnetic flux changing?

    i can not seem to figure out how is the magnetic flux is changing and thus the current is induced , "A "is constant (same disk is spinning ) and "B" is constant and does not change , so how is the current induced ? and more specifically how is the change of magnetic flux is happening ? thanks...
  40. alex.pasek

    What is the total flux of F across the given surface S?

    Homework Statement Considering the vector Field F(x,y,z))(zx, zy, z2), and the domain whose boundary is provided by S=S1∪S2 with exterior orientation and S1={(x,y,z)∈ℝ3 : z=6-2(x2+y2), 0≤z≤6}, S2={(x,y,z)∈ℝ3 : z=-6+2(x2+y2, -6≤z≤0}. Compute the total flux of F across S. Homework Equations...
  41. lulzury

    Photon Flux vs. Intensity: Which equation should be used to solve this problem?

    Homework Statement A sodium lamp emits light at the power P = 130 W and at the wavelength λ = 570 nm, and the emission is uniformly in all directions. (b) At what distance from the lamp will a totally absorbing screen absorb photons at the rate of 1.00 photon /cm^2s? Homework Equations 1...
  42. B

    Understanding Flux: Does it Have a Unit?

    Flux is the no. Of electric field lines per unit area..how can it have a unit
  43. T

    Magnetic Moment and permeablity

    Hi, I understand that magnetic flux is like electric current and will take the path of least resistance, but I really don't like the current analogy and here's one question where it doesn't help: Say you've got a piece of Ferro Iron where the magnetic moments are not lined up, you put a...
  44. E

    Calculating Magnetic Flux and EMF in a Circuit with Changing Current

    Consider a straight infinite wire that carries a current I. Suppose you place a square circuit near the wire such that the circuit and the wire lie on the same plane. The length of the sides of the circuit is l`. The nearest side of the rectangle is at a distance d from the wire. question is...
  45. Hardik Batra

    Electric flux linked with spherical shell having a hole?

    How much electric flux linked with the spherical shell having a hole?(consider the charge is outside the shell) I knew the flux linked with spherical shell is zero.(because it is closed loop.)
  46. M

    Flux Integral Evaluation Problem: Check My Workings and Get Advice

    Homework Statement Hello, So I've got to evaluate a flux integral, but I get 0. Could someone please, check my workings and give me advice. Please find my workings and the problem attached here as an image. Thank you very much!
  47. O

    Fluids - Squeezing flow - How to find force, work, and flux

    Homework Statement The initial separation of the pistons is 2cm. They are submerged in water at room temperature. I need to calculate the work required to have two pistons touch, find the volumetric flux of the water as a function of time, and the force at a given time Homework Equations...
  48. ZARATHUSTRA

    Magnetic Flux Φ and Moving Bar ζ: Investigating the Change

    consider the graph below, the bar of length ζ moving to the right with speed v in a uniform magnetic field B going out the page. i don't understand why does the textbook say that there is a change in the magnetic fluxΦ? i think the area doesn't change, although it's moving. the original...
  49. T

    Projected Area of a Cone in Electric Field Calculation

    Homework Statement Homework Equations Flux = ∫E.ds The Attempt at a Solution I need to get the projection of cone on a plane perpendicular to the electric field . The area thus obtained when multiplied by electric field would give the flux . I am not able to imagine the projected area...
  50. K

    What area does the flux formula refer to?

    I've been studying em induction and in my book it was explained by considering a metal rod of length l moving through a magnetic field and cutting through the field lines at a constant speed. So in time dt it moves through ds and they showed e=BA/dt, where A = l x ds(the area that the rod...
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