What is Magnetic induction: Definition and 81 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. D

    Magnetic induction by hammering

    Magnetism may be induced in iron rods by orienting them with the geomagnetic field and hammering (thus realigning their magnetic domains), according to Gilbert and others. If the rod has not been properly oriented towards the geomagnetic field, however, there must be a corresponding failure to...
  2. M

    What is the derivation of Maxwell's 4th equation for a static electric field?

    In my derivation of Maxwell's 4th equation from the empirical Biot Savart law, for a static electric field, I have that the curl of B is equal to the magnetic permeability times the current density. Now, the source coordinates (i. the circuit) are given by R_1 ( R is a vector). The field...
  3. Z

    Magnetic Induction Homework: Find Displacement FA

    Homework Statement A beam of electrons accelerated by a p.d. of 100V flies into a homogeneous magnetic field applied perpendicular to the plane of the paper towards the observer. The width of the field OP=L1=2cm. In the absence of m.f. the electron beam produces a spot at a point F on...
  4. Terocamo

    Transformer concepts (magnetic induction)

    Homework Statement The transfromer equation is given by\frac{Vp}{Vs}=\frac{Np}{Ns} for an ideal transformer. This equation is correct only if there are perfect flux linkage, the resistance of both primary and secondary coil is small and carries negligible current. The notes mention here if the...
  5. Terocamo

    Which Rod Rotation Induces EMF in a Magnetic Field?

    Homework Statement Which of the following action would cause and e.m.f. induced in the conductor? 1. The rod is rotating about an axis parallel to the B field through one end of the rod. 2. The rod is rotating about an axis perpendicular to the B field through one end of the rod. 3. The rod...
  6. K

    Can Faraday's Law of Magnetic Induction Lead to Anti-Gravity?

    Hi everyone... While going through some texts.. At one place i found that in faraday's law of magnetic induction, >a time varying magnetic field induces an electric field.. And, >a spatially varying electric field induces a magnetic field.. Which one of these is correct? I know of...
  7. S

    Writing the Magnetic Induction Eq. for a Rotating Magnetic Field

    Hello everybody, I have a question about the magnetic induction equation. I am interested in the non ideal case, i.e. when there is a non negligible diffusivity, however as regards my question I think that this is not relevant. I first ask the question and then give additional explanations...
  8. A

    Magnetic Induction at Point on Conductor: Biot-Savart Law

    Homework Statement What is the magnetic induction at a point on a current carrying conductor itself according to biot -savart law? is it zero, infinity? Homework Equations The Attempt at a Solution
  9. Y

    How to calculate the magnetic induction of ferromagnet

    1. There is a small ferromagnet,so it could product the magnet field. parameter:lenth 3mm; width 2mm ;thick 1mm magnetic susceptibility:2. 2.question If there is a position in three-dimensional space(x,y,z) . This position's magnetic induction is ?How to get it? I need...
  10. S

    Magnetic Induction Experiment Suggestion

    Hello, I am looking for ideas to demonstrate magnetic induction. There are a couple I've found, but I'm having trouble finding something with a little more excitement. The two I've seen are lighting a bulb with a changing magnetic field and launching an object by closing a switch connecting a...
  11. M

    Magnetic Induction In terms of Creating Charge

    Hi, I'm an industrial designer and I was wondering if there is a way to charge a battery through magnetic induction. I have heard that the way some stop lights work is there are coils below the road, and when the steel body of a car goes over it, it creates a change in charge in those coils...
  12. J

    Is the magnetic induction line closed

    It is said that every magnetic induction line is closed.but recently I happended to find one which isn't. Consider the magnetic field generated by a ring form circuit, the magnetic induction line which I have found is not closed is the one that go through the center of the circuit,which is...
  13. S

    EM: Magnetic induction at a point due to a line of current, or square coil.

    Hi everyone, (nb: I posted this in the introductory physics section, but maybe it should be here? I'm not exactly sure how to divide physics into introductory and advanced. I hope this isn't against the rules - it's only my second post!) I am trying to understand my EM course again, and I...
  14. A

    Magnetic Induction: Exploring Voltage Peaks, Flux & Magnet Orientation

    [b]1. In lab, we used a 400-turn coil test apparatus, mounted on an adjustable stand so a bar magnet could be dropped through it from different distances above it. In addition to the apparatus, we also used a voltage sensor and the Pasco interface used to display a graph of the induced voltage...
  15. R

    Deriving the equation for magnetic induction

    Homework Statement We have a straight wire with radius R. What is the magnetic induction through point A at a distance of r? In other words, derive the equation B=\frac{\mu_{0}i}{2\pi r} by using d\vec{B}=\frac{\mu_{0}i}{4\pi r^2}(d\vec{l} \times \vec{u_{r}}) Homework Equations...
  16. C

    Electro magnetic Induction problem. Simple one, but check wehre I am wrong.

    Electro magnetic Induction problem. Simple one, but please check wehre I am wrong. Homework Statement A magnet moving down, goes through a coil and exits it below. Plot the graph showing variation of induced emf in coil with time. Homework Equations emf = - Flux/Time The Attempt...
  17. B

    Explaining Magnetic Induction - Hello World!

    hello *We are able to explain why current is induced when piece of wire inside MF is pulled with force F[pull] ( wire is thus moving perpendicular to MF or at some angle ): *We can also explain why even if piece of wire is at rest, but instead MF is moving, a current...
  18. S

    A magnetic induction question

    Homework Statement A square of edge a lies in the xy plane with the origin at its center. Find the value of the magnetic induction at any point on the z axis when a current I' circulates around the square. Homework Equations B=u/4pi * lineint[(I'*ds' x R)/R^3)] The Attempt at a...
  19. S

    Magnetic Induction: Exploring Induced EMF & Faraday's Law

    induced emf! Hello, I am studying magnetic induction, induced emf, and faraday's law, that sort of thing. My book gives an example where the magnitude of a B-field is increasing at constant rate through an axis of a circular coil with N number of turns and a certain radius r, find the...
  20. J

    Magnetic induction in toroidal transformers

    Hello, If I take a small toroidal transformer and rotate a magnet over the top of it with the magnet's poles at 90 degrees to the coils, how does the presence of the permiable core affect the Lenz forces that are exerted on the magnet? Would the lenz forces be very small since the magnetic...
  21. S

    Another Faradays Law of Magnetic Induction

    A piece of copper wire is formed into a single circular loop of radius 12 cm. A magnetic field is oriented parallel to the normal to the loop, and it increases from 0 to 0.55 T in a time of 0.45 s. The wire has a resistance per unit length of 3.3*10^-2 ohms/m. What is the average electrical...
  22. D

    Calculating Magnetic Field to Overcome Friction in Metal Wire Setup

    Ok there are two plastic rails over which a metal wire is kept , the wire is kept prependicular to both plastic rails , over the rails.. The coefficient of friction is 'n' between the metal and the plastic . The mass of the plastic wire is 'm' , Calculate the magnitude of the Magnetic field B ...
  23. V

    Magnetic induction, Faraday's law and the likes

    Recently I started "studying" electromagnetic induction (O.K. that might be a bit of an overstatement, but I am interested in it, so it's just as well) and I came to the following important "discoveries": - one of the Maxwell's equations states (Faraday's law if my memory serves me correct)...
  24. A

    Magnetic forces aon currents and magnetic induction

    HELP ME PLEASE! Given B=0.80 T, a square coil with a single loop with length of each side of 20 cm, a current of 5.0 A where there is an external constant uniform magnetic field, what are the size and the direction of the magnetic force on just the lower section of the loop due to the 0.80 T...
  25. R

    Understanding Magnetic Induction Field B on Circular Coil Axis

    Just a quick question about finding the magnetic induction field B on the axis of a circular coil shown on page 7 on http://www.physics.gla.ac.uk/~dland/ELMAG305/Elmag305txt5.pdf I understand why the field must be along the x-axis but why does (dlxr )x become dlrsin(alpha)? alpha doesn't seem...
  26. J

    Magnetic Induction Problem

    An apparatus has two batteries in a row (negative-positive negative-positive is how the batteries go..the negative part is above the positive one in two consecutive batteries.). There is a switch after the two batteries, the wire holding the batteries is conected to conducting rails on both...
  27. M

    Questions on Magnetic Induction

    1.Why must you use insulated copper wire for the coils of an electromagnet? 2. How does the strength of a wooden core electromagnet compare with that of the iron electromagnet? 3. How does the magnitude of the current affect the strength of the electromagnet? 4. How does the number of turns...
  28. F

    Exploring Magnetic Induction: Horseshoe Magnets & Line Formation

    how are lines of induction formed due to 2 horseshoe magnets that are placed side by side but no contact? Are there websites that would show me about it?
  29. V

    Magnetic Induction vs. Field Strength

    What is the difference between the meanings of the terms magnetic induction and magnetic field strength? thanks in advance...
  30. A

    Magnetic Induction: Solving 3 Formulas

    Hello everybody and thanks so much for your help, (I know I have to improve my English) here is my big problem concerning 3 formula's : (It's just the beginning) -first at all,we have a magnetic field B created by the circulation of a current I into a spire (with a spoke a) on a point at a...
  31. R

    Can Rewinding Primary Coils Boost Low RPM Ignition in Modified Motorcycles?

    I am at the very end of my pitiful little rope and I do need some serious help with my electric/magnetic induction problem. About Me: I am a machinist and a motorcycle rider/racer, I know nothing about electricity or terms used other than I have found it rather unpleasant to use my body as a...
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