magnetic flux

  1. asadahmad_7869

    How to find the charge at time = t (at any instant)

    I was not able to derive the charge on the capacitor. But then, I arbitrarily assumed ##\phi=B.A## (Dot product of Magnetic field and Area) Then, proceeding as follows, ##\phi=BA\cos(\omega_0 t)## ##\frac{d\phi}{dt}=−BA\omega_0\sin(\omega_0 t)## Now at ##t=0, \phi=BA\cos(0)=BA## Therefore...
  2. Zack K

    Current induced on a coil by a changing magnetic flux in another coil

    I will first calculate the magnetic flux of the coil in motion. $$\frac {d\phi}{dt} = -\frac {dB_{loop}}{dt}A = -\frac{d}{dt}(\frac{\mu_o}{4\pi}\frac {2\pi NR^2I}{(R^2+z^2)^{\frac{3}{2}}})A$$differentiating in terms of ##z##, we get $$\frac {d\phi}{dt} =(\frac{\mu_o}{4\pi}\frac {6\pi^2...
  3. Andres Padilla

    How to measure the magnetic field/ induced fem in a system

    1. Homework Statement Hello, this is like an experiment of engineering.It is called a induction stove. The system consists of a bycicle, where I am going to pedal. This will turn a disk that have 20 small magnets around its circuference. Once the disk starts to turn, it will produce a constant...
  4. Yousuf Ejazi

    Calculate the induced EMF for angle α

    I have a question in my book and it’s confusing me a bit. I tried to search online for similar solved problems but couldn’t succeed. So here it goes: Calculate the induced EMF in a conductor loop when the angle between \vec{A} ~ and~ \vec{B} ~is~ changed ~from ~{0 °}~ to ~{α °} in 1...
  5. 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...
  6. Cardinalmont

    B Flux through a Coil

    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...
  7. Cardinalmont

    B 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...
  8. T

    B Temperature and magnetic flux density

    Hello all; I am new in this forum, currently in High School. For some time now, I have been looking online for a relationship between temperature and magnetic flux density of a ferromagnet; below the Curie point. However, I can't seem to find any relationship or formula. Do any of you know...
  9. B

    Magnetic Flux Questions from Japanese University Exam Papers

    Hello everyone, This is my first post here Firstly, I'd like to start by saying that it's my best intention to follow the rules on this forum. Therefore, if I've posted this in the wrong section please forgive me, I will try and learn the ropes quickly. One of my students has given me some...
  10. Cocoleia

    Magnetic flux, current and magnetic field confusion

    1. The problem statement Relevant equations: I am confused. When dealing with Ampères law: dl is supposed to be the length element? Like when we have Gauss' law for electric fields and we use a circular Gaussian surface, we have E(4πr^2)=Qenclosed/ε So in this case, when we have a circular...
  11. L

    Magnetic flux between 2 parallel wires

    1. Homework Statement Consider two long parallel wires each of radius a with a separation distance d between them. They carry current I in opposite directions. Calculate the magnetic flux through a section of length l, ignoring magnetic field inside the wires. My confusion lies in trying to...
  12. Y

    Calculating magnetic flux of a rod

    1. Homework Statement B = 0.02T L = 40 cm w = 10 rad/s a: Electromotive force between O and C = ? b: If electromotive force is the same - so what is the velocity? I found 2 ways of solution. See "3. The Attempt at a Solution " 2. Homework Equations φ = BA ε = -dφ(t)/dt 3. The Attempt...
  13. cheapstrike

    Self inductance of a coaxial system of cylinders

    1. Homework Statement A thin hollow cylinder of radius a is surrounded co-axially by another hollow cylinder of radius b, where b>a. An electric current I flows through them (I is into the plane of paper (x) in outer cylinder and coming out of plane of paper (.) in inner cylinder). Find the...
  14. I

    Magnetic Flux Through a Square Loop

    1. Homework Statement A loop of wire in the form of a square 1.50 m on each side, its plane makes an angle of 40.0° with a uniform magnetic field of 0.95 T. What is the magnetic flux through the loop? 2. Homework Equations Φ = BAcosθ A = s^2 3. The Attempt at a Solution I found the area of...
  15. G

    Magnetic flux and current directions of transformer

    Hello. Let's take a transformer picture first. The basic equation explaining how the transformer work is the equation of Faraday's law of induction. \begin{array}{*{20}{c}} {{V_P} = - {N_P}\frac{{d{{\rm{\Phi }}_B}}}{{dt}}\;\;\;\;\left( 1 \right).}\\ {{V_S} = - {N_S}\frac{{d{{\rm{\Phi...
  16. H

    Resulting magnetic flux in the core of a transformer

    In a transformer, let's say we have: I1, I2 - currents through the primary and secondary winding V1, V2 - voltages N1, N2 - number of turns F1, F2 - magnetic fluxes through core, produced by the currents I1 and I2 (they are opposing...) R - the reluctance of the core We have V1/V2 = N1/N2...
  17. moenste

    Find direction of current in a magnetic field

    1. Homework Statement The diagram shows a uniform magnetic flux density B in the plane of the paper. Q and R mark the points where two long, straight and parallel wires carry the same current, I, in the same direction and perpendicular to the paper. The line through QR is at right angles to the...
  18. kamhogo

    Finding the current in a solenoid

    1. Homework Statement A 40-turn, 4.0-cm-diameter coil with R = 0.40Ω surrounds a 3.0-cm-diameter solenoid. The solenoid is 20 cm long and has 200 turns. The 60 Hz current through the solenoid is I = Io sin (2Πft). What is Io if the maximum current in the coil is 0.20A? 2. Homework Equations...
  19. gsmtiger18

    Displacement current and magnetic flux through a wire loop

    1. Homework Statement A long straight wire has a line charge, λ that varies in time according to: λ = λ0e(-βt). A square loop of dimension, a, is adjacent to the wire (at a distance a away from the wire). Calculate expressions for the displacement current at the center of the wire loop and the...
  20. TheSodesa

    Mutual inductance of a long wire and a triangular loop?

    I originally posted this to the advanced homework -section, but maybe this isn't advanced enough to warrant being posted there :oops:. If a mod sees this, feel free to delete the original on the other forum. I'd do it myself, but I can't. 1. Homework Statement Calculate the mutual...
  21. S

    Electromagnet magnetic field strength

    1. Homework Statement 2. Homework Equations ##\oint_{C} Bd\ell = \mu I_{enc}, B_{normal}## continuous across boundary, ##H_{parallel}## continuous across boundary 3. The Attempt at a Solution $$\oint_{C} Bd\ell = \mu I_{enc} \rightarrow B = \frac{\mu NI}{2\pi r}$$ Any help much...
  22. T

    Flux in magnetic core according to special relativity

    Hi, So say you have a magnetic flux in a closed magnetic path circuit (like a TX core). Well I mean we draw arrows and stuff to indicate how the magnetic flux travels, but after watching this: I'm having trouble understanding why there is any flux moving through at all. Can someone please help...
  23. M

    Stern-Gerlach Magnetic Field

    1. Homework Statement For a Stern-Gerlach experiment, there is a apparatus designed to create a magnetic gradient. There is a dipole magnet. The radius of the convex pole is 5 cm, the radius of the concave pole is 10 cm. The convex pole as a 2 T magnetic field along its surface. (The apparatus...
  24. kostoglotov

    Energy dissipated by a loop of muscle in an MRI machine

    edit: turned out to be a calculator typo...mods feel free to delete this thread if you wish, I won't complain. 1. Homework Statement Having issues with part a) imgur link: http://i.imgur.com/4hzLyhb.jpg 2. Homework Equations Resistivity of muscle (from table in text): \rho \approx 13...
  25. pecchiaw12

    Trouble understanding - to + vs + to - current flow

    1. Homework Statement When reading about directions of magnetic flux in relation to current flow on pages 6 to 8 of http://www.free-energy-info.tuks.nl/Non-Ferrous-Magnet.pdf , I found that in figure 11 the current is travelling from + to - terminals, while in figure 12, the current flows from...
  26. 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} =...
  27. 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...
  28. 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...
  29. 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...
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