What is Magnetic flux: Definition and 366 Discussions

In physics, specifically electromagnetism, the magnetic flux through a surface is the surface integral of the normal component of the magnetic field B over that surface. It is usually denoted Φ or ΦB. The SI unit of magnetic flux is the weber (Wb; in derived units, volt–seconds), and the CGS unit is the maxwell. Magnetic flux is usually measured with a fluxmeter, which contains measuring coils and electronics, that evaluates the change of voltage in the measuring coils to calculate the measurement of magnetic flux.

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  1. 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...
  2. 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?
  3. 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.
  4. Kerrigoth

    Calculating multiple magnitudes for induced electric field

    Let's say I place two different size conducting loops inside of a uniform magnetic field. For the sake of the diagram I have the loops share a point, but just treat them as though they are not touching. Then I decrease the value of the magnetic field very quickly. \frac{dB}{dt} =...
  5. 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...
  6. 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...
  7. Dvorak

    Magnetic field created without an electromagnetic field?

    Magnetic fields are less harmful than electric field and also a lot safer than being exposed to electromagnetic radiation. If data transfer is possible through magnetic flux then cancers and all those kind of diseases can be avoided. So, the question again is can a magnetic flux(movement of...
  8. 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...
  9. 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...
  10. 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?
  11. 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...
  12. 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...
  13. D

    Exploring the Conservation Law for Magnetic Flux in Superconducting Circuits

    There is a conservation law for superconductors " the flux through a superconducting ring cannot change". This can be shown using Faraday's law: - E.M.F=-d/dt (BA) where B is the measured magnetic field passing through the ring and A is the area enclosed by the ring therefore for a ring...
  14. 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...
  15. Anakrystine

    Magnetic flux. Dont know where to start

    Homework Statement A circular area with a radius of 7.90cm lies in the x-y plane. A. What is the magnitude of the magnetic flux through this circle due to a uniform magnetic field B = 0.223T that points in the +z direction? B.What is the magnitude of the magnetic flux through this circle due to...
  16. N

    How is EMF induced in a pendulum under the influence of Earth's magnetic field?

    Homework Statement A simple pendulum with bob of mass m and conducting wire of length L swings under gravity through an angle 2 theta. The Earth's magnetic field component in the direction perpendicular to swing is B. The maximum potential difference induced across the pendulum is Homework...
  17. LunaFly

    Flux of Circuit made from Metal Bar on Parallel Rails

    Homework Statement [/B] A simple model of a railgun is a metal bar which runs on two long parallel rails. The two rails are connected to a charged capacitor with capacitance C and a resistor with resistance R. After charging, the capacitor can discharge through the circuit. You may assume that...
  18. B

    Stacked magnets with air gaps and the effect on magnetic flux

    I wasn't sure where to put this so mods feel free to move, So this is a problem I'm trying to solve for a masters project and simplified it is this; I essentially have a stack of magnets all separated by 4mm each magnet is identical and produces a magnetic flux of 17.5 gauss at its centre (all...
  19. 3

    Calculating magnetic flux density using Biot-Savart law.

    Hello, all. I have been working on the following problem and was wondering if someone could check my work and provide some valuable input: Here is my work: What do you guys think about my approach to this problem?
  20. 3

    Charge passing through a magnetic field of uniform magnetic flux density

    My reasoning: The magnetic force on charge q is Fm = qv x B B does not change |v|. Therefore, |Fm| is constant at time t > 0 and Fm is always perpendicular to the direction of movement of charge q. Fm behaves as a centripetal force, and thus the charge moves along the circumference of a...
  21. B

    Help me understand magnetic flux linkage

    Magnetic flux linkage = BAN B=magnetic field strength per unit area A=Area of conductor moved through the magnetic field N=Number of coils I don't understand when my physics textbook says the area of a single coil of wire moved through the magnetic field is π×radius of coil^2 as most of the...
  22. M

    Finding magnetic flux density from magnetization vector

    Homework Statement A long cylinder of radius a with magnetization vector M=M_0*(r/a)^2*a_φ. Find the magnetic flux density inside and outside the cylinder. Homework Equations J_m=∇×M J_ms=M×a_n[/B] A=(μ_0/4*π)*(∫(J_m/R)dv+∫(J_ms/R)ds) B=∇×A The Attempt at a Solution Basicly what I thought...
  23. S

    Total Magnetic Flux Density Law Problem

    We know Total Magnetic Flux B = B_0 + B_m Where, B_0 is the external field and B_m is the field inside a material. Now, we get, B = B_0 + μ_0*M (M is the magnetization) My question is - Do I always have to use μ_0 ? If yes then Why? The material isn't free space, is it?& also B =...
  24. B

    Is B more analogous to D or to E (electromagnetism)?

    In the book I'm reading on electromagnetic fields, the authors seem to associate the magnetic flux density B with the electric flux density D, and the magnetic field H with the electric field E. Now, my question is, wouldn't it make more sense to say B is the analog to E? Because E and B are...
  25. J

    Magnetic flux linkage and area as a vector

    Homework Statement A circular coil of diameter 24 mm has 40 turns. The coil is placed in a uniform magnetic field of flux density 85 mT with its plane perpendicular to the field lines. a) i Calculate the area of the coil ii The flux linkage through the coil. b) The coil was reversed in a...
  26. S

    What is the magnetic flux through the prism's right side?

    Homework Statement Now, ignore the lengths given in the photo. Height (y) = .640 meters Length (z) = 1.18 meters Base (x) = .320 meters Magnetic Field (B) = 3.5 Teslas in the +X direction Homework Equations The problem is to find the magnetic flux through the surface of the...
  27. B

    Magnetic flux density calculation for high permeability material

    Hi to all of you, As the Biot-Savart-Law is based on experimentations in air, i like to know how to calculate the magnetic flux density in material with much greater permeability, where the circular like shape of the field distribution troughout the vicinity does not apply. Does anyone has a...
  28. Feodalherren

    Magnetic Flux & Current in a Dropped Magnet & Wire Loop

    Homework Statement A bar magnet is held above the center of a wire loop lying in the horizontal plane, as shown in the figure below. The south end of the magnet is toward the loop. After the magnet is dropped, what is true of the current in the resistor as viewed from above? (Select all that...
  29. P

    How Does Induced EMF Vary Inside a Solenoid?

    Homework Statement The current in a solenoid (you may treat it as a long solenoid of length 2.0 m, turns, and radius 0.5 m) is decreasing at a rate of 1.7 A/s. What is the EMF at a point .35m inside the solenoid? Homework Equations B=N(mu_0*I)/(2a) where B=magnetic field, N=turns per...
  30. 2

    Does Magnetic Flux Remain Constant in Changing Magnetic Fields?

    I know that the equation for magnetic flux is \Phi=\int \vec{B} \cdot dA. It seems to me that this is like integrating the density function a rod with respect to x, which simply gives you the mass which is constant. I was wondering whether the same thing applies here: is magnetic flux a constant?
  31. lonewolf219

    Electric flux versus magnetic flux

    I'm taking E & M II... Would anyone agree that the following statements are true? An electric field changing in time gives rise to a displacement current. A magnetic field changing in time gives rise to an electromotive force.
  32. A

    Finding the resistance, magnetic flux, and current of a loop section

    ...based on the angle. Homework Statement Figure 30-78 shows a wire that has been bent into a circular arc of radius r = 24.0 cm, centered at O. A straight wire OP can be rotated about O and makes sliding contact with the arc at P. Another straight wire OQ completes the conducting...
  33. L

    Magnetic Flux through 1 loop due to current on the other

    The scenario is the following, I am given 2 loops with the same radius, r, a distance of d, and same current of I. In the left loop the current goes counter clockwise, in the right loop the current is clockwise. The two loops centers lie on the same axis which are perpendicular to the plane of...
  34. L

    Magnetic Flux through 1 loop due to current on the other

    The scenario is the following, I am given 2 loops with the same radius, r, a distance of d, and same current of I. In the left loop the current goes counter clockwise, in the right loop the current is clockwise. The two loops centers lie on the same axis which are perpendicular to the plane of...
  35. J

    Faraday's Law and Magnetic Flux

    Homework Statement Hi, this is not a homework problem per say but I am just struggling with some concepts related to my homework. I am struggling with the concepts of flux linkage and flux cutting. Are these one and the same thing? The following statement in my book is where my confusion has...
  36. J

    Magnetic field strength and magnetic flux

    Hi, please could someone help with my confusion over these two qauntities. In class we recently learned that magnetic field strength (B) is the number of flux lines (measured in Webers) per square metre. The magnetic flux on the other hand is the total number of flux lines (measured in Webers)...
  37. 4

    What is the Magnetic Flux Exiting a Cube?

    Homework Statement Here is the prompt: http://imgur.com/FTFz0fZ Homework Equations Magnetic flux = ∫B dot dA Net Flux for closed surface = 0 The Attempt at a Solution For part a: magnetic flux = (7.74 ^i + 4 ^j + 3 ^k)T * (0.254 m)^2 ^i = 7.74 T *...
  38. Solibelus

    Difficulty understanding EMF due to a changing magnetic flux

    Hello everybody, I'm studying classical electrodynamics and I'm having a difficulty grasping the concept of EMF. I'll try to explain what causes my confusion. Say I've got a conducting loop, an electrical wire, with some resistance R which contracts (or expands) with time. Let's put that loop...
  39. A

    > Why Change Of Magnetic Flux Induces Current In It?

    Why change of magnetic flux with the time through a coil induces current in it? Please tell me that what happen to charge in the coil if the magnet or electromagnet wave around this? Also, why a constant magnetic flux does not induces current?
  40. baby_1

    Find magnetic flux density(B) via vector potential(A)

    Hello As you know we can find the flux density (B) via vector potential with this equation So with this equation and solution at first i try to find vector potential completely then use above equation Problem: Solution: my approach: now we use curl A to find B we find that but it...
  41. T

    Magnetic Flux through a Closed Surface

    Homework Statement Using the divergence theorem, evaluate the total flux of a magnetic field B(r) across the surface S enclosing a finite, connected volume of space V, and discuss its possible dependence on the presence of an electric field E(r). Homework Equations ∇.B=0 The...
  42. D

    Magnetic flux of sliding bar on rails

    Homework Statement "A metal bar which runs on 2 long parallel rails are connected to a charged capacitor with capacitance C and a resistor with resistance R. Assume no friction and perfect conductors. The rails are cylindrical of radius R separated by distance d. The bar is a distance x...
  43. M

    Calculating Magnetic Flux in Spool Coil with Air Gap - Formula and Example

    Homework Statement The attached picture shows a spool coil on a iron core with an air gap measuring 2.5mm. The spool is coiled by 0.5mm2 with rho cu = 0.0175 Ωmm2 /m. The average winding diameter for the spool is 3.18cm. Compute the magnetic flux in the spool. Homework Equations...
  44. P

    Magnetic Flux: Does Direction Matter?

    Homework Statement So this is more conceptual than anything. Say there is a wire loop on the x,y axis and a permanent bar magnet above it on the z axis. I understand according to Faraday's law that as the north end of the bar magnet moves towards the loop the magnetic flux is increasing...
  45. V

    Finding Magnetic Flux Through a Wire Frame

    Homework Statement A square wire frame,in the x-y plane, carrying a current 'I' and with side length 'A' is kept at a distance 'A' from the y-axis . Find the magnetic flux through the other half of the plane(not containing the square loop).Homework Equations The magnetic field due to line...
  46. R

    What Causes Delay in Magnetic Flux Propagation?

    Hey all, I'm working on a project now where I am using a solenoid driven at a 10Hz AC current to create a magnetic field on a solid piece of low carbon iron, and then using a smaller solenoid to capture the magnetic flux coming from the iron. By measuring the phase of the resulting waves...
  47. Entanglement

    What is the relationship between magnetic flux and coil wire?

    Magnetic Flux= BA is A the surrounding area affected by the flux or the area of the coil itself that is affected by the flux
  48. B

    Help with theory about magnetic flux loops and tornados

    hi i have some crazy ideas about tornadoes,lightning and storms emitting magnetic flux loops interacting with the Earth's own magnetic properties and do not have enough electrical schooling to know if it is even a possibility. i was hoping i could get a more learned opinion. the thread is...
  49. N

    Magnetic flux through triangular ring

    Homework Statement Very long wire carrying current I is surrounded by a brass ring of a triangular cross section. (figure attached) Show that ψ = μ° I h ------ (b - a ln ((a+b)/b) 2∏b Homework Equations A = (μ°I/2∏ * ln x) az (according to one of the solutions, where x is the...
  50. 2

    Magnetic flux pinning sometimes there and sometimes not.

    Hello. As far as I know about superconductors, if you put a superconducting material in a magnetic field and then cool that material below its critical temperature, the material should lock to that magnetic field (magnetic flux pinning). Now I have seen videos where the locked magnet/material is...
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