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. J

    Magnetic flux through smaller coil within solenoid

    Homework Statement A solenoid has 235 turns of wire wrapped along its length of 27 cm. The diameter of the solenoid is 1.5 cm. In the middle of the solenoid is a smaller coil of diameter 1.0 cm with 50 turns of wire along its 2.0 cm length. The two coils are coaxial. A current of 15 A is in...
  2. A

    Magnetic flux through loop inside of solenoid

    Homework Statement A solenoid has 1800 turns of wire and is 125 cm long and 10.0 cm in diameter; see Figure P.14 (attached). A circular wire loop of diameter 5.0 cm lies along the axis of the solenoid near the middle of its length as shown. (a) If the current in the solenoid initially is...
  3. G

    Mystery of Magnetic Flux: Example 6.2 Revealed

    http://img.photobucket.com/albums/v235/gsan_bot/magnetic1.jpg" Refer to example 6.2 shown in the picture, the magnetic flux = -1.2t and the deriative time of magnetic flux should be -1.2, thus, the flux is decreasing and the direction of the induced current should be reverse. but why it say...
  4. I

    Understanding Air-Core Coils and Magnetic Flux Lines

    1. an air-core coil consists of 10 layers, and each layer is 11cm long and has 400 turns. the average radius of the layers is 2.25 cm. the flux density within the coil can be closely approximated by using the formula: B=µIN/2r which of the following best describes this statement? 1) true...
  5. D

    Divergence of magnetic flux density

    Homework Statement This is from my textbook Engineering Electromagnetics by John Buck and William Hayt 7th Edn, pg 238 in the chapter titled "The Steady Magnetic Field": Homework Equations Divergence theorem: \oint_S \textbf{B} \cdot d\textbf{S} = \int_{\mbox{vol}} \nabla \cdot...
  6. S

    Magnetic flux formula confusion

    Hello everyone, In the magnetic flux formula in our textbook it says Ø = BAcosø and somewhere else I saw it as Ø=BAsinø. I don't know which one to use. If F=BIL sinø why does magnetic flux have cos in it formula. If something is perpendicular don't we have to use sine. Any help would be...
  7. R

    Solving for Total Magnetic Flux and Induced EMF

    Homework Statement http://img164.imageshack.us/img164/3313/qqqqo3.jpg Find the total magnetic flux through the coil at t=0 Given that the rate of change of flux at any time,t, is equal to 2 \pi f \phi sin 2 \pi ft, find the maximum instanteous value of the induced emf at any time & the...
  8. L

    How does the wire know the magnetic flux has changed?

    If we have a metal wire and a magnetic field "inside" it, when the flux of the magnetic field changes, then the wire "reacts" by "creating" an induced current. After learning this law, it eventually came to my mind the question: how does the wire know that the magnetic field flux has changed...
  9. H

    Magnetic flux in a coil, find current

    Homework Statement 1.) Problem (exam question that I got wrong and want to figure it out) A circluar coil of radius a=.35m rotates at a frequency of 120 hz in a constant magnetic filed of B=.8T. The axis of rotation is perpendicular to the field the coil has N =340 turns it has a resistance...
  10. B

    Calculating Magnetic Flux from Induced Voltage in Proximity Coils

    Hi All, I have setup a small experiment with a pulsing coil--Coil 1 to produce a pulsed magnetic flux, say we do not know the specifications of this coil like number of turns on the windings, voltage to the coil, flux density etc. There is another coil --Coil 2 of known specifications...
  11. C

    Tough tough question: Calculating magnetic Flux in water

    Hey all, so i have a cylindrical 1.61 tesla magnet with pole orientations (+)_)- being spun at 350RPMs in a cylindrical body of water. The body of water dimensions are 19inches tall, and 13.5 diameter. The magnet is centered in the container of water. Also, the magnet is spinning with a...
  12. manjuvenamma

    Magnetic lines of force and magnetic flux

    "The number of magnetic lines of force passing through any area in a magnetic is known as magnetic flux" So the definition of flux goes. But I find it rather ambiguous and loose. Or is that I am missing some vital point? The magnetic lines of force are not real, they are imaginary lines...
  13. O

    Transformer Voltage Multiplication Factor Calculation

    The output voltage of a 74 W transformer is 13 V, and the input current is 34 A. By what factor is the voltage multiplied? V_{s} ------=? V_{P} Honestly I am not sure exactly where to start in solving this problem.
  14. T

    Magnetic Flux Through a Coil

    Homework Statement A long straight wire on the z-axis carries a current of 3.0 A in the positive direction. A circular loop in the xy-plane, of radius 10 cm, carries a 5.0-A current, as shown. Point P, at the center of the loop, is 25 cm from the z-axis. A circular coil of four turns, 2 cm...
  15. C

    Effect of Changing Magnetic Field on Flux through a Coil

    Homework Statement You hold a wire coil perpendicular to a magnetic field B. If the magnitude of B increases while its direction remains unchanged, how will the magnetic flux through the coil change? Check all that apply: The flux is unchanged because the position of the coil with...
  16. B

    Calculating Magnetic Flux in a Bent Square Loop with a Uniform Magnetic Field

    Magnetic flux...PLEASE HELP! Homework Statement A 13.5 cm × 13.5 cm square bent at a angle 90°. A uniform 0.463 T magnetic field points downward at θ=33° angle. What is the magnetic flux through the loop? (a=6.75 cm, b=13.5 cm, c=6.75 cm.) Homework Equations The Attempt at a...
  17. B

    Calculating Magnetic Flux in a Solenoid-Loop System with Varying Angles

    Magnetic flux...help please! Homework Statement A 2.02-cm-diameter solenoid passes through the center of a 8.62-cm-diameter loop. The magnetic field inside the solenoid is 0.75 T. A.) What is the magnetic flux through the loop when it is perpendicular to the solenoid? B.) What is the...
  18. B

    Magnetic Flux through a Loop Calculation

    Simple Magnetic Flux Prob... Homework Statement What is the magnitude of magnetic flux through the loop? (a=22 cm, b=27 cm, B1=1.2 T, B2=1.7 T.) Homework Equations MF = AB cos theta The Attempt at a Solution MF = AB So wouldn't I just do ((0.2m * 0.2m) * 1.2) + ((0.22m *...
  19. R

    How Does Rotating a Semicircular Wire Loop Affect Magnetic Flux?

    Homework Statement A loop of a wire has the shape shown in the drawing. The top part of the wire is bent into a semicircle of radius r = 0.24 m. The normal to the plane of the loop is parallel to a constant magnetic field ( = 0°) of magnitude 0.75 T. What is the change in the magnetic...
  20. V

    Understanding Magnetic Flux: Visualization & Beyond

    What is the definition of Magnetic Flux? My textbook tells me that it may be 'visualised as the total number of magnetic field lines rather tan their concentration... be aware that this is NOT a definition.' thank you
  21. E

    Magnetic flux between coaxial conductors

    Homework Statement A coaxial conductor has the length L. The inner conductor of radius a carries a current I in the z direction. The outer conductor is very thin and has the radius b. Calculate the total magnetic flux enclosed within the conductors. Homework Equations Magnetic flux...
  22. U

    Magnetic Flux Density: B, \phi, H - True or False?

    magnetic flux density is denoted by the B symbol magnetic flux is denoted by the \phi symbol so why do people use B as if they were referencing to magnetic flux? "magnetic flux density is a measurable quantity indicating the strength of a field" ...this was stated by a teacher of...
  23. P

    Why a magnetic flux in closed surface area is always 0?

    Why a magnetic flux in closed surface area is always 0?
  24. P

    What is change in the magnetic flux (delta B)?

    What is change in the magnetic flux (delta B)? Like on this http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/emfchb.html"
  25. K

    Doubling voltage. Halving amps. Quadrupling wire length and ohms. More magnetic flux?

    So what produces a solenoid's magnetic field? Voltage or Power? Voltage = Current * Resistance Power = Current^2 * Resistance Magnetic field magnitude of a solenoid = magnetic constant * turns * current We can quadruple the turns using the four times of the same type of wire, but that will...
  26. C

    What is the magnetic flux through the solenoid

    [b]1. Magnetic field inside a long solenoid with cross-sectional area A is given by B=(mu)nI where n is the number of turns per unit length and I is the current. Suppose that the current is given by I(t) = I(0)e^(a*t) where t is the time and a and I(0) are constants. What is the magnetic flux...
  27. M

    Understanding Magnetic Flux and Density: Relationship and Comparison

    I read somewhere that increasing the current flowing through a solenoid will increase the magnetic flux density but cannot increase the magnetic flux. From what I gather magnetic flux is the space the magnetic field covers or the range of the magnetic flux lines and flux density is how many...
  28. M

    Magnetic Flux (Induction - Magnet through a coil)

    Is the incoming flux (first peak) equal in magnitude to the outgoing (second peak) flux? Why? A magnet was dropped through a solenoid, this experiment was completed twice, a graph of Voltage (V) vs. Time (t) was made for each experiment. The area under each curve is defined to be equivalent to...
  29. K

    Solve Magnetic Flux from Straight Wire & Rectangular Loop: Wb

    Homework Statement A long straight wire carries a current 36 A. A rectangular loop with two sides parallel to the straight wire has sides 7.5 cm and 15 cm with its near side a distance 3 cm from the straight wire as shown in the figure. The permeability of free space is 4π e -7 T*m/A. Find...
  30. A

    How do magnetic flux lines behave around external defects in steel structures?

    Hi All, Can anyone help with the following problem (see attached image)? The left diagram shows a magnet clamped to a piece of steel (in the example the steel is the wall of a pipeline). The lines of flux are shown to pass through the pipe wall. I am happy with this diagram and what it shows...
  31. M

    How does winding a metal wire into a coil create magnetic flux?

    I was reading there that if you wind a piece of metal wire into a coil it creates a magnetic field. Does this wire have to have current running through it? I know that a changing electric current creates a magnetic field but how does winding a piece of metal wire into a coil create magnetic flux?
  32. D

    Understanding Magnetic Fields: Explaining Magnetic Flux and Flux Density

    Hi. I am having a little trouble grasping the concept of a magnetic field. My book doesn't explain it very well. I understand that any magnet has a magnetic field, which is the space around it in which other magnets are subject to a force due to the magnet. What I am having trouble with...
  33. A

    Find Total Magnetic Flux Through a Wire and Loop

    a) There is an infinitely long wire carrying a current I. There is a square loop with resistance R a distance a from the wire in the same plane. Find the total magnetic flux through the loop. b) There is an infinitely long wire carrying a current I in the z-direction. There is a square...
  34. cepheid

    Magnetic Flux Through a Wire Coil

    Hi, This problem confused me the first time around, but I think I've got it. I just want a confirmation that my reasoning is correct. I know I have the correct answer, but what is important is the method of arriving at it. Homework Statement A wire is being wound around a rotating wooden...
  35. J

    Magnetic flux through metal

    I need help solving this question: The magnetic flux through a metal ring varies with time t according to B = 3( at 3 - bt 2) Tm2, with a = 2.00 s-3 and b = 6.00 s-2. The resistance of the ring is 3.20 . Determine the current induced in the ring at t = 1.00 s. I know that you have to take...
  36. X

    Archived Magnetic Flux through a Cylinder

    Homework Statement A long, straight wire carrying a current of 4.00 A is placed along the axis of a cylinder of radius 0.500 m and a length of 3.00 m. Determine the total magnetic flux through the cylinder. Homework Equations Flux = BA B(long wire) = (((4 * pi) * 10^-7) * I )/ (2 * pi * R)...
  37. D

    How Do You Calculate Magnetic Flux Density on a Solenoid's Axis?

    Homework Statement Determine the magnetic flux density at a point on the axis of a solenoid with radius b and length L, and with a current I in its N turns of closely wound coil. Homework Equations Biot-Savart law: myI/(4pi)integral(dlcross er/R^2) there er is the unit vector in...
  38. A

    Electromagnetism - Magnetic flux between infinite wire and rectangular loop

    Homework Statement The figure shows a rectangular wire loop, around which a current I flows, and and an infinite straight wire. The wire lies in the plane of the loop and is parallel to, and a distance d from, the side AB. (see attachment) Show that the amount of magnetic flux generated...
  39. S

    Understanding Flux Linkage: Exploring Examples & Confusions

    (N.B. All the following assumes that the magnetic fields are in vacuo). I'm having trouble deciding what flux linkage is (as in Faraday's law etc.). What is the proper definition? My textbook gives the example of a coil moving through a magnetic field, tracing out a cylinder - the flux...
  40. N

    How to tell the magnetic flux a certian distance from a solenoid?

    How to tell the magnetic flux a certian distance from a solenoid?? This is about a coursework problem that I've been trying to figure out for the past few weeks. This is my context, for those wanting to know i'm trying to predict the high of the ring, in the jumping ring experiment. For...
  41. Amith2006

    Magnetic flux through a solenoid problem

    Homework Statement In one of the problems dealing with solenoid, they gave the value of flux through the cross-section of the solenoid(say 1.6x10^(-3)Weber). Do they mean that this is the flux through a single turn of the solenoid? I get the answer if i take it this way. Homework...
  42. S

    Magnetic flux thorugh a loop of wire

    Homework Statement Griffiths Problem 7.8 A square loop of wire (side a) lies on a table dsiantce s from a very long straight wire, which carries a current I, as shown in teh figure. Find the flux of B through the loop Homework Equations Flux of B is given by \Phi_{B} = \int \vec{B}...
  43. A

    Component of magnetic flux density - huh?

    hiya If 'b' is the length of a wire, and 'I' current running trough it, then if put a wire inside magnetic field ( not perpendicullary and also not parallel to magnetic field lines, but some angle in between the two ), then magnetic force on a wire will be: F = I * b * B * sin[angle] where...
  44. E

    Magnetic Flux and Induced EMF in a Coil

    In a physics laboratory experiment, a coil with 210 turns enclosing an area of 12.7 cm^2 is rotated during the time interval 3.70 \cdot 10^{−2} sfrom a position in which its plane is perpendicular to Earth's magnetic field to one in which its plane is parallel to the field. The magnitude of...
  45. Y

    How to Calculate Magnetic Flux on a Surface Along a Wire?

    Along a wire (of radius r) a current i is crossed from one. Calculate the magnetic flux through the surface S, inner to the wire. http://img138.imageshack.us/my.php?image=cilindrodb4.jpg I think \phi_b= \int B dS= BS B=\mu_0 i/2\pi r How to calculate S if I have not the length of wire...
  46. A

    What is the relationship between magnetic flux and EMF?

    Hi everyone, Apologise for so many questions within a short period of time. I'm in the midst of my holidays and I can't clarify my doubts in school. For a particular A.C generator, it has a large rotating rectanglar coil rotating at 50 rev per second in a B field strength of 0.29T. It has...
  47. W

    Calculating Magnetic Flux: Understanding the Formula and Variables

    A rectangular loop of wire 24 cm by 72 cm is bent into an L shape, as shown in Figure 23-37. The magnetic field in the vicinity of the loop has a magnitude of 0.034 T and points in a direction = 22° below the y axis. The mangnetic field has no x component. Find the magnitude of the magnetic...
  48. J

    Help Solving Magnetic Flux Question - Can You Assist?

    I have a question dealing with magnetic flux that I cannot seem to get. Please help Question= A 2m conductor is formed into a square and placed in the xy plane. a magnetic field is oriented 30 degrees above the horizontal with a strength of 6T. What is the magnetic flux through the...
  49. A

    Magnetic Flux: Exploring What it Means and Its Units

    I started reading Lectures on Electrical Engineering Vol I, Steinmetz. I thought I should be able to understand most of it, but I don't get the first page! It says that: 'The total number of lines of force issuing from a magnet pole is called its magnetic flux. The magnetic flux, phi, of a...
  50. Reshma

    Magnetic Flux Q: How Is Flux Independent of Surface?

    This question might seem rather naive. We define the magentic flux through a loop by \Phi = \int \vec B \cdot d\vec a. But an infinite number of different surfaces can be fitted to a given boundary line...so how is the flux independent of the nature of the surface used?
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