electromagnetic induction Definition and Topics - 51 Discussions

Electromagnetic or magnetic induction is the production of an electromotive force across an electrical conductor in a changing magnetic field.
Michael Faraday is generally credited with the discovery of induction in 1831, and James Clerk Maxwell mathematically described it as Faraday's law of induction. Lenz's law describes the direction of the induced field. Faraday's law was later generalized to become the Maxwell–Faraday equation, one of the four Maxwell equations in his theory of electromagnetism.
Electromagnetic induction has found many applications, including electrical components such as inductors and transformers, and devices such as electric motors and generators.

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  1. J

    Solenoid pendulum frequency

    The flux enclosed by the loop consisting of the solenoid, wires and conducting rod at an angle θ is Φ = blBsinθ, then using small angle approximations and differentiating the induced emf can be found. I know that there must be some torque opposing the motion but am unsure how to proceed.
  2. patric44

    I What is the origin of Lorenz force?

    hi guys one of my friends asked me about the origin of the electromagnetic induction, I know somehow that its related to the Lorenz force as the electrons in the conduction band of say the coil interact with the magnetic field ,which results in separation of electrons and positive ions which...
  3. Narayanan KR

    A Question on Skin Effect and Eddy Currents

    When you try to create time varying magnetic fields in solid metals, there is severe heating due to eddy currents, when you increase the frequency, just like in NDT(non destructive testing) the magnetic field is pushed away from the core to the periphery due to eddy currents opposing the field...
  4. Narayanan KR

    Interesting Links Between Faraday's EM Induction and EPR

    Imagine a magnet moving up and down so that its flux 'B' cuts the copper rod to produce an alternating emf, suppose if the movement is fast enough such that its frequency equals to the electron spin resonance frequency given by F = B x 2.8 Mhz per gauss, neglecting skin effect, more copper...
  5. Narayanan KR

    Orientation of Electric Fields in a Bucking Coil Setup

  6. Narayanan KR

    An Interesting Question on Faraday's Law of Electromagnetic Induction

    On examining Maxwell's third equation which is about time varying magnetic fields (Faraday's electromagnetic induction) we find that time varying magnetic fields produce loops of electric fields in space irrespective of whether a coil is present or not, if any coil is present then these loops of...
  7. L

    Maximum Induced Voltage of an AC Generator

    I would like to ask a question about the induced voltage of an AC generator. So, according to a graph I found on Google, the maximum induced voltage is reached when the loop is parallel to the loop. (The graph shown below.) Then I was wondering, what if the loop is initially (when it is at 0...
  8. C

    Is there a difference between Faraday’s induction experiments?

    Faraday first demonstrated his law of induction by showing that when he created a current in one wire coil it created a second current in a second coil. Another experiment showed the same effect. When he moved a magnet through a wire coil, it created a current in the coil. My question is this...
  9. KarlsShwarzschild

    Electromagnetic induction (finding ΔΦ).

  10. nomadreid

    E-M fields mutual induction in E-M radiation

    In electromagnetic radiation, the electric field and the magnetic field mutually induce each other: but my impression is that it would be better to say that they are two aspects of the same wave, so that there is no time between them. However, an alternative would be that there would be that...
  11. I

    Electromagnetism EMF induction calculations

    A square conducting loop of side length a is in a non-uniform magnetic field. The loop occupies the first quadrant of the xy plane, i.e. the space between the origin (x, y) = (0,0) and the point (x,y) = (a, a). The magnetic field is in the +z direction. Develop an expression for the magnitude of...
  12. U

    Current induced from a changing magnetic field

    This question is motivated by Problem 7.12 in Griffiths Electrodynamics book. I have not included it in the homework section, because I have already solved it correctly. However, I question whether my solution which agrees with the solution's manual is correct. Relevant Equations: $$\Phi =...
  13. Physics lover

    Amount of magnetic energy stored in a cylinder

    I first calculated Magnetic field at a distance x using Ampere's law.Then i took an element and wrote its inductance using L=Flux/Current. Then i integrated from a to b. But i arrived at nothing. Help.
  14. TOUHID11

    Constructing an equation for the induced EMF in terms of the radius of the circular loop

    In order to calculate for the curl of the induced electric field for a loop moving in a uniform magnetic field, and using the cylindrical coordinate system for a curl, it's my understanding that since the B field is in the 𝑧̂ direction, then so is the partial time derivative of B, and therefore...
  15. christang_1023

    Understand Faraday's Law and Lenz' Law

    Above is an example figure. 2. When a ring in a changing magnetic field is not complete (i.e. open circuit with a small gap), how to analyze the emf of the ring? According to the general form of Faraday's law, ## \oint \vec{E} \cdot d \vec{s} = -\frac{d \Phi}{dt} ##, I deduce that although it...
  16. N

    Challenging question about electromagnetic induction

    Homework Statement I have been stuck on this for weeks Homework Equations ∫E.dl = -dφ/dt The Attempt at a Solution Total EMF (V) = -dφ/dt (Where φ is the magnetic flux through the loop) ⇒V = -A(dB/dt) (Since Area remains constant) ⇒V = -Ax (x=dB/dt) ⇒V = -2xl^2 I do not know how to proceed.
  17. J

    The direction of induced current and magnetic field produced

    Homework Statement The figure below shows a small circular loop of wire in the plane of a long, straight wire that carries a steady current I upward. If the loop is moved from distance x_2 to distance x_1 from the straight wire, what will be the direction of the induced current in the loop and...
  18. T

    Difference between Vav and Vrms

    Homework Statement [/B] I encountered this problem during my exam. A coil of 50 turns, each with area 0.02m2 is rotated in a uniform magnetic field of magnitude 0.4T. The coil is rotated at a frequency of 60Hz. Given the average power generated is 50W, what is the resistance of the wire...
  19. Y

    Why does Fleming's right hand rule apply for induced current

    I know that the right hand rule applies for induced currents, and the left hand rule is for motors, but why? It doesn't seem to connect with any other physics laws and is very counter-intuitive that the current will flow in one direction rather than the opposite direction if both are...
  20. S

    Electric Field induced by a Magnetic Field inside a Solenoid

  21. S

    I Phase differences in Transformers

    How is the phase difference between the current in the primary coil and induced e.m.f. in the secondary coil be 90*??
  22. V

    Doubt in electromagnetic induction

    Homework Statement suppose a coil is placed in a changing magnetic field and the circuit is not closed will the current induce in the coil Homework Equations The Attempt at a Solution What I thought was that the current flows only in a closed circuit because it needs a potential difference...
  23. Pushoam

    Induced electric field

    Homework Statement Homework Equations The Attempt at a Solution The emf gets induced due to the changing flux. The flux through the rod remains 0. So, there is no induced emf. I don’t know how to calculate induced electric field. But as there is no induced emf, so there is no induced...
  24. A

    Magnetic/electromagnetic induction

    Suppose there is a coil around a C-shaped iron core with a dipole magnet in the gap as shown in the dynamo below. As the magnet is spinning, in order to oppose the force, a changing pole is produced in the iron. (Eg. As N-pole approaches the iron core, a north pole is induced to oppose the...
  25. Toby_phys

    The slowing down of a Farady disc

    Homework Statement A homopolar generator consists of a metal disc of radius ##a## and a central axle which has radius ##a/4##. The disc has resistivity ##\rho## and thickness ##t##. It is rotated in a uniform magnetic field ##B## about an axis through the centre, which is parallel to ##B## and...
  26. F

    Electromagnetic induction

    Homework Statement We have a coil with cross-sectional area of 2.4m^2. Magnetic flux density is of 0.29T Number of turns are 1. Initially the coil is parallel to magnetic field lines. (Coil's normal vector is perpendicular to field vector) Calculate the change in magnetic flux when coil is...
  27. C

    Flux through rim created by moving circuit and induced EMF

    In Purcell- Electricty and Magnetism book, in the chapter on electromagnetic induction, I found the following explanation regarding the magnetic flux through a circuit of area ##S##. Consider the circuit in figure, moving in a time ##dt## in a magnetic field ##B##, constant in time (but not...
  28. A

    B EMF in a straight conductor

    I just read in my text book that it is impossible to harness electricity from the induced emf if the velocity of a conductor is parallel to its straight length. Let me elucidate further: a magnetic field goes into the page and a straight conductor is moved straight down or up (perpendicular to...
  29. hackhard

    Graphite electromagnetic induction

    since graphite conducts. if spiral shape is drawn with pencil on the wall (thick , dark lines) will a voltage difference appear between inner and outer end of the spiral when a varying magnetic field is switched on, normal to wall
  30. mikemartinlfs

    Electromagnetic Induction (Long straight wire above circulua

    Homework Statement A circular loop of wire is placed next to a long straight wire. The current I in the long straight wire is increasing. What direction is the current that's induced in the circular loop? Homework Equations The Attempt at a Solution I'm aware that the answer is clockwise...
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