What is Flux density: Definition and 144 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. B

    Magnetix flux density & Zero scalar potential

    Hi Can anybody tell how I can prove that the magnetic flux density is perpendicular to external boundaries with imposed zero magnetic scalar potential? Thanks Bag
  2. M

    Magnetic fieldstrength, magnetic flux, magnetic flux density

    I have a problem understanding magnetic fieldstrength, magnetic flux, magnetic flux density. Some questions that answered may ease my understanding: Is it true that the magnetic field strength B in the core caused by a current in a wire wound on a the same torodial magnetic core is...
  3. S

    Normal/Tangential magnetic flux density problem

    [PLAIN]http://img232.imageshack.us/img232/7172/60746674.png Homework Statement The picture attached to this question shows a magnetic slab with μr = 50. A thin conducting film (with μr = 1) lies on top of the slab and carries a surface current of 1.0[A/mm] directed out of the page. If...
  4. L

    Calculating Magnetic Flux Density in a Hollow Cylindrical Conductor

    π²³ ∞ ° → ~ µ ρ σ τ ω ∑ … √ ∫ ≤ ≥ ± ∃ · θ φ ψ Ω α β γ δ ∂ ∆ ∇ ε λ Λ Γ ô Homework Statement An arbitrarily long hallow cylindrical electric conductor shown carries a static electric current density J=\hat{z}J0. Determine the magnetic flux density B in the hallow region of radius a. Your result...
  5. R

    How Does Copper Wire Shape Affect Magnetic Flux Density?

    A 1mm-diameter copper wire is shaped into a square loop of side = 4cm. It is placed in a plane normal to a magnetic field increasing with time as \vec{B}=1t\hat{z}Wb/m2. Calculate the magnetic flux density at the center of the loop. I found that the magnitude of the induced current is...
  6. S

    How to Calculate Flux Density in a C-Core with an Air Gap?

    Homework Statement A "c" core has a 500 turn coil carrying 1.5 A, wound around it and a conductor carrying 25A is placed in the air gap. If the air gap has the dimensions: L= 125mm D= 20mm and a reluctance of 250,000 at/wb determine a) the flux B) the flux density c) the force...
  7. C

    Magnetic flux density vs magnetic flux

    i'm having trouble distinguishing between magnetic flux and magnetic flux density...can someone please explain to me? also why is it sometimes used interchangeably?
  8. K

    Determine Flux Density to Induce 1V at 6000rpm

    1. A loop of wire is placed between the poles of a magnet. The magnetic field can be assumed uniform between the poles. The formed by the loop within the field of the magnet is 20cm2. (i). Determine the magnitude of the flux density required to induce a maximum voltage of 1V when the loop is...
  9. K

    Magnitude of Flux Density

    1. A loop of wire between the poles of a magnet, the magnetic field is uniform between the poles. The are of the loop of wire within the field is 20cm sqaured. Determine the magnitude of flux density required to induce a mx voltage of 1v when the loop is rotated at 600rpm 2. B= Flux x A...
  10. S

    Electromagnetism, flux density Vs. field size

    With a set coil if you increase the electric flow does the flux density increase And/or the magentic field decrease/ maintain/ increase in size..? Thanks once again, Sem.
  11. B

    Find Flux Density On One Side of Dielectric Boundary Given Boundary Conditions

    Homework Statement A dielectric interface is defined as 4x + 3y = 10 m. The region including the origin is free space, where D1 = 2ax - 4ay + 6.5az nC/m2. In the other region, εr2 = 2.5. Find D2 given the previous conditions. Homework Equations an12 = ± grad(f)/|grad(f)| D2n = D1n =...
  12. L

    Inverse relationship - neutron flux density with sunspot cycle

    Just over half-way down this page:- http://www.embedded.com/columns/technicalinsights/220301380?cid=RSSfeed_embedded_news it says:- "These sunspot counts show variation on a cycle of roughly 11 years. By overlaying Oulu neutron measurements with sunspot count data since 1964, we see that...
  13. Z

    Electric Flux Density / Electric Field Intensity

    Hey people, I'm struggling to understand exactly what Electric Flux Density D and Electric Field Intensity E are. So far, my understanding is that D depends on relative permittivity, while E depends only on the permittivity of free space. Also, I understand that D reflects only the free...
  14. Y

    Why is the unit of flux density different from the unit of electric flux?

    The unit of Electric flux is N.(m^2)/C. But how is it , that the Flux density(which is nothing but flux per unit area) has a unit of C/(m^2).? Also , I have a book in Electromagnetic Engineering which states that "'electric displacement' and 'electric flux' are the same thing and both are...
  15. L

    Magnetic Flux Density in a Circular Loop

    Homework Statement A current flows in a circular loop consisting of a single turn.If the same wire is bent into a circular loop of 2 turns and the same current is passed through the loop,the magnetic flux density at the centre will change by a factor of ...? (ans: 4 ) Relevant equations B...
  16. Nabeshin

    CMB Flux Density: Deriving For Present Cosmology

    Does anyone know where I can find numbers (or how to derive) the CMB flux density (W/m^2)? I'm only really interested in our present cosmological time, so a solution may assume the CMB to be at a constant temperature.
  17. C

    Find Flux Density in Iron Ring: 1A Current, 5cm Length, 200 Turns, 1mm Gap

    an iron ring of mean length 5 cma has an air gap of 1mm and a winding of 200 turns. If the permeability of iron is 300 when 1A current flows through the coil find the flux density. its answer is 94.2 mWb/m^3 kindly help how I would drive it
  18. R

    No Such Thing As Magnetic Flux Density

    I would like to put this out for argument that there is no such thing as magnetic flux density. Since magnetism is a wave like on water's surface, it is continuous. Is there a 'water wave density?" I think not. Unless you mean the distance between wave peaks. But flux lines are only arbitrary...
  19. J

    Why Does Divergence of Electric Flux Equal Volume Charge Density?

    Question: Can someone remind me why the divergence of the electric flux is equal to the volume charge density, \nabla \bullet \vec{D} = \rho_{v} (where \vec{D} is the electric flux density). Thoughts: The divergence measures the flow of a field out of a region of space. The del operator takes...
  20. J

    Flux density of solenoid beyond the pole

    I’m making a solenoid and I’m trying to work out how much force it exerts on an object X meters away from it. I’m using F=BIL to get the force but I don’t know the equation for getting the magnetic flux density of the solenoid other than B=(uNI)/L but that’s just for the centre and I need it for...
  21. D

    Electric flux density a direct measuer of E?

    Temp message This is what a book says - “The number of lines per unit area through a surface perpendicular to the lines is proportional to the magnitude of the electric field in that region. Thus, the field lines are close together where the electric field is strong and far...
  22. A

    Magnetic Flux Density at different points about a solenoid

    Homework Statement For my physics investigation I am required to first find the theoretical magnetic flux denisty at different points about a solenoid. The points are outside the solenoid: along the axis but past the ends and; perpendicular to the centre of the solenoid but outside. So far...
  23. O

    Flux Density and Capitance relationship?

    Is there a way to relate flux Density with capacitance (Parallel plate capacitor). Yes/ No... I will be thankful if you tell me the equation is there is a relationship. In case we cannot relate them, then is there a way to relate any electromagnetic parameter with parallel plate...
  24. Z

    Specific Intensity, Flux, Flux Density, Radiative Transfer

    Hi, I'm new to the technical aspects of astronomy and I'm having trouble quantifying what the definitions of some of these terms are. I can find equations that relate most of them, but I'm not sure how to use any of them. The terms are specific intensity, flux, flux density, and monochromatic...
  25. L

    Flux Density at Certain Point?

    Homework Statement Someone else posted up this image on yahoo answers and my question is very similar except the numerical figures are different really. http://s3.supload.com/free/Picture_258.jpg/view" How can i solve for for the flux density at the point using the 3-A current...
  26. L

    Calculate Flux Density of Current Loop

    Homework Statement Loop like an "O" with current moving to the left Diameter = 8cm Current = 15A FIND THE FLUX DENSITY OF THE CURRENT LOOP IN THE PLACE OF THE LOOP? Homework Equations B(flux density)=F(magnetic flux)/A(area) B=H(magnetic field strength)*Permeability H(magnetic field...
  27. 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...
  28. A

    What is the flux density at point p?

    Homework Statement 1) What is the flux density at point p in Fig "see link below". due only to the 3-A current in the portion of wire 2 shown? 1) 1.64 x 10^-5 Wb/m^2 2) 2.45 x 10^-5 Wb/m^2 3) 3.11 x 10^-5 Wb/m^2 4) 3.65 x 10^-5 Wb/m^2 2) In which direction does the flux at...
  29. R

    Quick question about the flux density through a solenoid.

    Homework Statement the flux density through a solenoid is given by B=\mu_o n I Where n is the number of turns per unit length. The number of field lines per unit area is proportional to B. I am assuming that at or near the centre of the solenoid the number of field lines per unit area...
  30. 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...
  31. S

    How Does Current and Magnetic Field Affect the Force on a Power Line?

    Homework Statement A power line runs along the Earth's equator where the magnetic flux density, B, points from south to north and has a strength of 50*10-6T. The current in the line is 500A flowing from west to east. Find the magnitude and the direction of the fore acting on eath kilometer...
  32. R

    Calculating Energy Flux Density and Candle Power

    Homework Statement A standard candle has radiant intensity equal to 1/683 W/sr. [The unit of measurement is watts per steradian. The steradian (sr) is the standard unit for solid angles: If a patch on the surface of a sphere of radius r has area A, then the solid angle subtended by the...
  33. 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...
  34. M

    Researching Torque, Current and Flux Density

    Homework Statement For this question you must research, to help you with working out your answer a) A dc motor develops a torque of 600Nm when its armature carries a current of 30 Amperes. Predict the torque that will be developed when a 12% increase in flux density has taken place and the...
  35. 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...
  36. O

    Solving for Flux Density in a Flat Matter-Dominated Universe

    Homework Statement A population of sources in a flat matter-dominated universe has a number-density n_0 at the present epoch and a monochromatic luminosity P(\nu) \propto \nu^{-\alpha} at frequency \nu. Show that the flux density S(\nu_0) observed at the present epoch from a source at redshift...
  37. S

    The Physics of Electric Flux Density Vector (D)

    Why is D called the "electric flux density vector"?
  38. 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...
  39. V

    Infinitisemal magnetic flux density

    These Q's are probably simple for those of you who have/completed a course in Vector Calculus. But I'm only a higschool/secondaryschool student, so I haven't. 1. I'm not sure how the infinitisemal magnetic flux density d\textbf{B} from a wire element d\textbf{l} with a current I, which is...
  40. E

    Calculating electric field from radiant flux density

    Hi, The problem is stated as follows: "A laser provides pulses of EM-radiation in vacuum lasting 10^{-12} seconds. If the radiant flux density is 10^{20} {\frac{W}{m^2}}, determine the amplitude of the electric field of the beam." So far, I figure that the period of one wave is...
  41. B

    Magnetic flux density and Hall probe

    I'm planning an investigation on how magnetic flux density midway between opposite poles of 2 bar magnets varies with separation of the bar magnets (using a Hall Probe). [simply as shown in attachment] To do this, I'll need to calibrate a hall probe (which I think is done by working out the...
  42. C

    Calculating neutrino flux density

    Third and final A2 Physics paper tomorrow. Currently struggling with one of the articles we have been given to study before the exam. It's all about neutrinos. I've been given some questions to try, educated guesses by teachers on what could come up on the exam paper. "If the Sun is 150 Gm...
  43. M

    Magnetic Flux Density and the Relationship to Force and Units

    My physics teacher today taught my class the formula with magnetic flux density... Force on a wire in a magnetic field F = BILsin(theta) the part i am enquiring about is the B in which he explained to be B is the magnetic field strength (measured in Tesla's) He also said 1T =...
  44. J

    Solving a Flux Density Problem: Explaining E and B Field Amplitudes

    I have no ideal how to do this problem. Can someone explain it to me? What formula would i use? An isotropic quasimonochromatic point source radiates at a rate of 100 W. What is the flux density at a distance of 1 m? What are the amplitudes of the E and B fields at that point?
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