After Oersted’s discovery that a magnetic field exists around an electric current, scientists began to wonder if a magnetic field could, in turn, produce an electric current.
This current was only observed during the actual closing of the switch and again when the switch was opened. Electromagnetic induction, simply put, is the production of voltage across a conductor situated in a changing magnetic field or a conductor moving through a stationary magnetic field. Induction uses electromagnetic energy to heat cookware made of magnetic material (steel, iron, nickel or various alloys). This entry was posted in Degree, High School, Plus Two, Technical and tagged Electromagnetic Induction, GENERATOR, Induction Cooker, MOTOR, TRANSFORMER by sree. Electromagnetic induction is a process in which a conductor cuts through a stationary magnetic field lines (or conductor placed in a changing magnetic field) causes the production of a voltage across the conductor.
The large generators in power stations generate the electricity we need using this process. In practice, the changes are induced in a coil of wire because the current created is increased by the number of turns of wire in the coil.
This law is named after the German physicist Heinrich Friedrich Lenz (1804–1865), who announced it in 1833.
The law of electromagnetic induction was first presented by Michael Faraday in 1831 and therefore it is also called Faraday’s law of electromagnetic induction. Fleming’s right hand rule helps us to predict the direction of induce current relative to the motion of conductor. Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. Electric fields and magnetic fields are just different components of the electromagnetic field.
Alfred and Sam29 are quite correct, but the Maxwell equations and saying electric and magnetic fields are just different components of one thing, the electromagnetic field, is just a (nicely consistent) way of representing what is observed in nature. Then, all you have to do is see there's no reason to suppose the relationship is one-way only. Then if you supply the magnetic field from outside, if it's two-way, you should see a current, and you do. Take a flashlight battery, and take a short piece of wire connected to one end of the battery, and tap it on the other end.
Again, it may be easier to see that, because of conservation of energy and whatnot, the relationship between current and magnetic field has to be two-way. Then, Maxwell's equations make a beautifully concise explanation of that two-way relationship.
Moving the wire through the magnetic field is physically the same as increasing the magnetic field at the coil. As Alfred correctly pointed out, both the electric and magnetic fields are fundamentally the same field, the electromagnetic field - they are just different components. Not the answer you're looking for?Browse other questions tagged electromagnetism electric-fields magnetic-fields or ask your own question. Possible to generate an electromagnetic field from moving an object through a magnetic field? How does the electric field pulse propagate during a change in the magnetic vector potential? I violated academic integrity unknowingly by sharing assignment resources with fellow student. Every magnet creates a magnetic field due to the arrangement of the atoms in the material, in very simple terms, the atoms are spun so that most of the electrons are on one side of the atom, creating a negative charge on one side, while the lack of electrons on the other side of the atom exposes the positive charge of the protons in the nuclei.
Electromagnetic induction essentially is where a magnetic field or flux causes the flow of electrons in a conductive material. Now, what happens as our magnet passes through our coils is that the electrons are pushed and pulled creating our alternating current, so the current switches directions based up on whether the electrons in the coils are being attracted or repeled. I did base my ideas on a few other sites concerning charge and polarisation difference at the poles which perhaps I should have quoted as maybe they also got it wrong, but more likely I did – I think I over simplified it somewhat by ignoring the electron movement in my initial diagram. Larry, i have heard that when you spin the rotor (and magnets) around in an alternator there is a force other then the friction of the bearings repelling the motion. Electromagnetic InductionWe have seen previously that when a DC current pass through a long straight conductor a magnetising force, H and a static magnetic field, B is developed around the wire. The magnetic flux developed around the coil being proportional to the amount of current flowing in the coils windings as shown. Therefore, the magnetic field strength of a coil is determined by the ampere turns of the coil. But what if we reversed this idea by disconnecting the electrical current from the coil and instead of a hollow core we placed a bar magnet inside the core of the coil of wire. Likewise, if we kept the bar magnet stationary and moved the coil back and forth within the magnetic field an electric current would be induced in the coil. Electromagnetic Induction was first discovered way back in the 1830’s by Michael Faraday.
So what Michael Faraday discovered was a way of producing an electrical current in a circuit by using only the force of a magnetic field and not batteries. Likewise, if the magnet is now held stationary and ONLY the coil is moved towards or away from the magnet the needle of the galvanometer will also deflect in either direction.
In other words, Electromagnetic Induction is the process of using magnetic fields to produce voltage, and in a closed circuit, a current. If we were able to move the magnet in the diagram above in and out of the coil at a constant speed and distance without stopping we would generate a continuously induced voltage that would alternate between one positive polarity and a negative polarity producing an alternating or AC output voltage and this is the basic principal of how a Generator works similar to those used in dynamos and car alternators. In small generators such as a bicycle dynamo, a small permanent magnet is rotated by the action of the bicycle wheel inside a fixed coil.

The simple dynamo type generator above consists of a permanent magnet which rotates around a central shaft with a coil of wire placed next to this rotating magnetic field. Faraday’s Law tells us that inducing a voltage into a conductor can be done by either passing it through a magnetic field, or by moving the magnetic field past the conductor and that if this conductor is part of a closed circuit, an electric current will flow. But a changing magnetic flux produces a varying current through the coil which itself will produce its own magnetic field as we saw in the Electromagnets tutorial. Likewise, if the magnetic flux is decreased then the induced emf will oppose this decrease by generating and induced magnetic flux that adds to the original flux.
Lenz’s law is one of the basic laws in electromagnetic induction for determining the direction of flow of induced currents and is related to the law of conservation of energy.
According to the law of conservation of energy which states that the total amount of energy in the universe will always remain constant as energy can not be created nor destroyed. But the conductor may not actually be part of the coils electrical circuit, but may be the coils iron core or some other metallic part of the system, for example, a transformer.
Eddy currents generated by electromagnetic induction circulate around the coils core or any connecting metallic components inside the magnetic field because for the magnetic flux they are acting like a single loop of wire. The changing magnetic flux in the iron core of a transformer above will induce an emf, not only in the primary and secondary windings, but also in the iron core.
Eddy current and hysteresis losses can not be eliminated completely, but they can be greatly reduced.
These laminations are very thin strips of insulated (usually with varnish) metal joined together to produce a solid core. Round wire is enamelled to provide electrical insulation and has no effect on a coils magnetising properties. 3:How does the relative permeability of ferromagnetic material very with magneto motive force? In 1831, an English scientist, Michael Faraday discovered that magnetism could produce electricity.
Through this simple experiment Faraday had discovered the method for inducing an electric current by means of a magnetic field. The principles of electromagnetic induction are applied in many devices and systems we use today, for example electrical generators, induction motors, transformers, and most other electrical machines.
When the unit is turned on, the coils produce a high frequency alternating magnetic field, which ultimately flows through the cookware.
According to this rule, extend the thumb, forefinger, and the middle finger of the right hand in such a way that all three are mutually perpendicular to each another. Because when you disconnect the wire from the battery, the magnetic field in the electromagnet doesn't just disappear, its change induces current in the coil. This can be summarized as: a changing magnetic field creates a changing electric field (and vice versa). I mean why a charged conductor produce magnetic field or why when we cut magnetic flux, it induces current ?
By this logic, naturally, if you were to somehow change one component (by moving a magnet or something of that sort), it would lead to a change in the other. Before them, many physicists tried to answer the same question using their own approaches, and they failed. In the very simplified diagram to the left, the  nuclei are blue and the electrons are orange and their arrangement produces the  different overall charges with more electrons flowing to one end of the magnet.
This is actually important to us in explaining what’s happening in our alternator, our north pole of the magnet is negatively charged, the south has a positive charge.
If you have any decent info on the subject that you can point me towards that would be great. I have had quite a few years of education in this area and was actually teaching a class at a technical school here which lead me to find your site.
For instance Lorentz force is something that I don’t know much about other than what I can find on Wikipedia and the like.
If the wire is then wound into a coil, the magnetic field is greatly intensified producing a static magnetic field around itself forming the shape of a bar magnet giving a distinct North and South pole. If additional layers of wire are wound upon the same coil with the same current flowing through them, the static magnetic field strength would be increased. With more turns of wire within the coil, the greater the strength of the static magnetic field around it. Then by either moving the wire or changing the magnetic field we can induce a voltage and current within the coil and this process is known as Electromagnetic Induction and is the basic principal of operation of transformers, motors and generators. Faraday noticed that when he moved a permanent magnet in and out of a coil or a single loop of wire it induced an ElectroMotive Force or emf, in other words a Voltage, and therefore a current was produced. This then lead to a very important law linking electricity with magnetism, Faraday’s Law of Electromagnetic Induction.
When the magnet stops moving and is held stationary with regards to the coil the needle of the galvanometer returns back to zero as there is no physical movement of the magnetic field. Then by moving the magnet back and forth towards the coil the needle of the galvanometer will deflect left or right, positive or negative, relative to the directional motion of the magnet. Then the action of moving a coil or loop of wire through a magnetic field induces a voltage in the coil with the magnitude of this induced voltage being proportional to the speed or velocity of the movement. Alternatively, an electromagnet powered by a fixed DC voltage can be made to rotate inside a fixed coil, such as in large power generators producing in both cases an alternating current.
As the magnet spins, the magnetic field around the top and bottom of the coil constantly changes between a north and a south pole. This voltage is called an induced emf as it has been induced into the conductor by a changing magnetic field due to electromagnetic induction with the negative sign in Faraday’s law telling us the direction of the induced current (or polarity of the induced emf).
This self-induced emf opposes the change that is causing it and the faster the rate of change of current the greater is the opposing emf.

In other words, an induced current will always OPPOSE the motion or change which started the induced current in the first place and this idea is found in the analysis of Inductance. We now know that when a relative motion exists between a conductor and a magnetic field, an emf is induced within the conductor. The induced emf within this metallic part of the system causes a circulating current to flow around it and this type of core current is known as an Eddy Current. Eddy currents do not contribute anything towards the usefulness of the system but instead they oppose the flow of the induced current by acting like a negative force generating resistive heating and power loss within the core. The iron core is a good conductor, so the currents induced in a solid iron core will be large.
The laminations increase the resistance of the iron-core thereby increasing the overall resistance to the flow of the eddy currents, so the induced eddy current power-loss in the core is reduced, and it is for this reason why the magnetic iron circuit of transformers and electrical machines are all laminated.
Orsted discovered that an electric current would move a compass needle, showing him that an electric current generated a magnetic field. The current could only be induced however when the magnetic field about the conductor was changing.
Molecules in the cookware move back and forth rapidly, causing the cookware to become hot and cook the food.
In order for you to see this page as it is meant to appear, we ask that you please re-enable your Javascript! Note that the induced current will flow in a direction that opposes the movement of the wire. Moving the magnet closer changes the magnetic field at the coil, creating an electric field in the wire. This also explains why when you cut a magnet in half you will get 2 magnets, not a separate south and a north pole. This means that they will always try to attract an opposite charge, so when a magnet passes through or near an object with good electrical conductivity, the electrons in the conductor will be attracted to the south pole of our magnet, while the north pole  will repel the electrons. Direct current is where the current flows in only one direction, classically this is described as going from positive to negative and in most electronics this is the model that is used, however, in physics it’s considered the other way around!
There are of course numerous textbooks, but I understand that you are looking for a nice summary. Eventually I want to build up some decent sized wind turbines so understanding all of this is a must, please feel free to add more.
This rotational movement of the magnetic field results in an alternating emf being induced into the coil as defined by Faraday’s law of electromagnetic induction.
This self-induced emf will, by Lenz’s law oppose the change in current in the coil and because of its direction this self-induced emf is generally called a back-emf. However, there are electromagnetic induction furnace applications in which only eddy currents are used to heat and melt ferromagnetic metals. Furthermore, the eddy currents flow in a direction which, by Lenz’s law, acts to weaken the flux created by the primary coil. The cooktop’s glass-ceramic surface is unaffected by the magnetic field since it contains no magnetic material. The induce current is always from negative to positive direction, that is opposite to the direction of conventional current. I suggest you look up the laws, and that would answer your question better than any of us here could.
This then creates the polarisation effect we see in magnets and this is also where naming conventions jump into confuse matters!
This creates a movement in the electrons, essentially creating a flow of current, some materials will have a better conductivity as the electrons are able to move more freely.
Consequently, the current in the primary coil required to produce a given B field is increased, so the hysteresis curves are fatter along the H axis. 2 What is the maximum induced voltage that could be produced by ordinary or rather domestic magnets and coils, meaning by the magnets and coils you could usually use at home. Faraday believed that when a current flowed through one helix the magnetic field it created would be channeled to the other helix by means of a permeable iron ring. The heat of the pan will warm the glass; however, the cooktop will remain much cooler to the touch than other smoothtop surfaces. You can see in my basic diagram above how the magnet will attract and repel the electrons (orange circles) in the wire thus creating the alternating flow of electrons or current – without getting too complicated alternating means the current flows in 2 different directions which produces a sine wave.
If the positive charges move counterclockwise on the track (electrons moving clockwise) then north is up (skyward) and south is down groundward. My suggestion is to look up the Lorentz force – you need to put on your 3-d thinking cap for that.
However, when he closed the switch no steady current registered on the galvanometer, but it did register a brief surge of current. A ferromagnetic material placed close by gets likewise excited and the electrons in their atoms follow suit to match the permanent magnet’s orientation.
How many number of coils must one make to insure a current is induced by those ordinary or small temporary magnets.
The picture you drew would be what happens to atoms in the dielectric material of a capacitor or some solid-state storage devices.

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