What is the difference between magnetism and eletromagnetism?
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Good question:\n\nThere are two ways to create a magnetic field. One is to move charges or  create time dependend electric fields, that's part of the classical electrodynamics and referred to as electromagnetism.\n\nThe other one is through the "elementary magnets" in a substance. These elementary magnets are related to the spin of the subatomic particles, for example the electrons in a crystall lattice. That's what you usually call the magnetic properties, like ferro-, para-, ... magnetism.\n\nAlthough it seems that these are quite different things they are related to each other by the Einsteins theory of relativism.\n\nConsider a chain of moving electrons, each having an electric field. In the reference system of the electrons the just have the usual electric field of a resting electron. But a resting observer would see a different distance between the electrons because of the relativistic length dilation, and because of that feel a different electric field, if calculated properly this would explain electromagnetism as a relativistic correction to the electrodynamics.\n\nThe basic equation of quantum dynamics is the Schrödinger equation, which is a non relativistic equation and couldn't predict the spin. Dirac (and Klein and Gordon) made some relativistic extensions to the Schrödinger equation, and it showed up that now the extended Schrödinger equations (Dirac and Klein-Gordon equations) now contain the spin of the elementary particles.\n\nSo yes: From a phenomenological point of view there is a difference, and no, from a higher point of abstraction they are both relativistic effects and there is no difference.
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>>Theory of magnetocrystalline anisotropy\n\nThe direction of a magnetization relative to body that supports it is determined mainly by two effects, shape anisotropy and magnetocrystalline anisotropy. The first arises from magnetostatic effects and the second from spin-orbit coupling between the spins and the lattice of the material. The magnetostatic effects can be calculated from micromagnetic calculations, but the magnetocrystalline anisotropy must be computed from the electronic structure of the material. This is an important quantity because it determines whether a magnetic material can be made into a good hard magnet, a good soft magnet or neither. Hard magnets are an essential component of electromagnetic motors and soft magnets are an essential component of transformers.<<\n\nThe rest of that quote can be found in the source link:
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Not that big!\n\nMagnetism is stronger than gravity by order of thousands.\nThe earths magnetic field is bigger and stronger than the earths gravitational field.\nMagnetism is stronger than gravity otherwise you would not be able to pick things up with a magnet
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Magnetization of materials\n\nFerromagnetic materials can be magnetized in the following ways:\n\n* Placing the item in an external magnetic field will result in the item retaining some of the magnetism on removal. Vibration has been shown to increase the effect. Ferrous materials aligned with the earth's magnetic field and which are subject to vibration (e.g. frame of a conveyor) have been shown to acquire significant residual magnetism.\n    \n* Placing the item in a solenoid with a direct current passing through it.\n    \n* Stroking - An existing magnet is moved from one end of the item to the other repeatedly in the same direction.\n    \n* Placing a steel bar in a magnetic field, then heating it to a high temperature and then finally hammering it as it cools. This can be done by laying the magnet in a North-South direction in the Earth's magnetic field. In this case, the magnet is not very strong but the effect is permanent.\nMagnetization of materials\n\nFerromagnetic materials can be magnetized in the following ways:\n\n* Placing the item in an external magnetic field will result in the item retaining some of the magnetism on removal. Vibration has been shown to increase the effect. Ferrous materials aligned with the earth's magnetic field and which are subject to vibration (e.g. frame of a conveyor) have been shown to acquire significant residual magnetism.\n    \n* Placing the item in a solenoid with a direct current passing through it.\n    \n* Stroking - An existing magnet is moved from one end of the item to the other repeatedly in the same direction.\n    \n* Placing a steel bar in a magnetic field, then heating it to a high temperature and then finally hammering it as it cools. This can be done by laying the magnet in a North-South direction in the Earth's magnetic field. In this case, the magnet is not very strong but the effect is permanent.
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Ferromagnetism is the phenomenon that deals with three metals: iron, cobalt, and nickel.  These metals have unpaired electrons in their valence atomic orbitals and thus form a small magnetic field (the region that encompasses this magnetic field is called a domain).  A piece of one of these metals, however, has all of its domains oriented in several directions and thus there is very little net magnetic field.  When these metals interact with an external magnetic field, however, the domains all align in the same direction, thus causing these these metals to have magnetic properties.
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Hysteresis is the slight difference between how something reacts going one way compared to how it acts going the other way.\n\nA typical example is a magnet. As it magnetizes, it passes through the origin (the point at which 0 electric field intensity equals 0 magnetic field intensity). This is because the initial charge of magnetism is going into an "empty" container, so to speak.\n\nHowever, when the magnet is demagnetized (or the field is flipped to the opposite polarity), there will be a small amount of "residual" magnetism from the first charging that will tend to "fight" against the reversal. What this really means is that the reverse polarity charge does not follow the exact same path ... and does not pass through the initial origin at all.\n\nYou could look at this as filling and then emptying a glass with water - the first time you fill it, the glass started out completely dry ... which meant you could put X many molecules of water into it. Then you dump it out ... but a few molecules remain adhered to the glass surface (this would be the residual). The next time it's filled, you add as much as the first time (less the residual).\n\nWhen you empty it again, it leaves a couple of molecules attached. Not necessarily the same ones as the first time, but approximately the same amount. Hence there is now a hysteresis effect occurring when you fill/empty the glass.
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Paramagnetism is a form of magnetism which only occurs in the presence of an externally applied magnetic field. Paramagnetic materials are attracted to magnetic fields, hence have a relative magnetic permeability greater than unity (or, equivalently, a positive magnetic susceptibility). However, unlike ferromagnets which are also attracted to magnetic fields, paramagnets do not retain any magnetisation in the absence of an externally applied magnetic field.\n\nDiamagnetism is a form of magnetism that is only exhibited by a substance in the presence of an externally applied magnetic field. It is the result of changes in the orbital motion of electrons. Applying a magnetic field creates a magnetic force on a moving electron in the form of F = qv × B. This force changes the centripetal force on the electron, causing it to either speed up or slow down in its orbital motion. This changed electron speed modifies the magnetic moment of the orbital in a direction opposing the external field.
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Magnetism is caused by  electrical charges in motion. This is not necessarily something unique to electrical equipment, which is the case for electromagnetism, but also for permanent magnets. It is the motion of the electrons around the nuclei, and also the spin of the electrons, that cause the magnetism in a natural magnet. The magnetic field of Earth is believed to come from movements inside the planet, where oceans and rivers of melted metals exist.\n\nI can only think of two types of magnet; natural magnet and electro-magnet.
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Well even though humans have known about magnets for thousands of years, the real reason they work is still somewhat mysterious. Depending on how deep you want to investigate, it can be a very complicated phenomenon. \n\nA magnet is, at its foundation, caused by the movement of electrical charge (yes this is the Biot-Savart Law). When charges (like electrons for example) move, they produce magnetic fields. If a charge moves in a loop, it creates a magnetic field. The magnetic field can be basically represented by an invisible set of arrows in space, that point in a direction. In the case of the loop, the arrows of the magnetic field will point out of the loop for a positive charge moving counter clockwise (this is the so-called "right hand rule"), and into the loop for a charge moving clockwise (some pictures are in the reference attached). \n\nThe magnetic field has a "north" end and a "south end". The little arrows from our moving charge are pointing in the "north" magnetic direction, and away from the "south" magnetic direction. It is a mysterious and interesting property of electromagnetism that two objects with fields that oppose each other, i.e., the little arrows of the field do not line up, so either the north end of one field is facing the north end of the other field, or the two south ends are facing each other, repel, or resist movement of the two objects towards each other with some force. \n\nOn the other hand, if the little arrows line up, the two objects attract each other with some force. \n\nThe little arrows are aligned along the so-called "magnetic lines of force". \n\nThe forces that result from magnetic fields (and for that matter, electric fields) are fundamental forces, and part of the four fundamental forces of the universe (strong, weak, electromagnetic and gravity). It is believed that these forces are caused, at their base, by particles passing "messenger particles" back and forth. In the case of electromagnetism, the messenger particle is a photon. How this actually works is still somewhat poorly understood, and is involved with the world of quantum mechanics, which is very counterintuitive but interesting. \n\nHowever, what is important is that we understand it well enough to make models of magnetism, and to make predictions based on those models which we can verify and use. All of electricity and electric motors are based on our ability to design systems with magnets and to be able to build and use them.
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I believe that to reverse the polarity of and electromagnet you need to reverse the eletric current becarse the move ment of eletrons makes magnets
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All of the above.\n\nActually even Magnetism is affected by heat.  Heat a magnet and it will lose its magnetism.\n\nChemical composition will also change.
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Nope, the magnetic information (not electronic!) doesn't weigh anything, it's all related to the orientation of the "magnetic moment" (up or down) of the atoms i.e. the way atoms are turning (to make it simple). they're not heavier if they turn in one sense than if they does in the other
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Magnetic forces, electric forces are bi-polar: there are North and South poles on magnets, as well as positive and negative charges. As a result the forces can be attractive or repulsive.\n\nGravity is mono-polar in the sense that the force between two masses is always attractive.
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regular magnet is a permanent one and electromagnet is an artificially created magnet which behaves as a magnet when current is passed through a wire around a iron bar\nelectromagnets are widely used
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Most magnets are formed by moving electrons. Each moving electron creates a small magnetic field. If lots of electrons are moving along the same path, they create a bigger magnetic field. Because of this you can make a magnet by using electric current. If you wrap a coil of wire around a piece of iron (like a big nail) and then put electricity through it using a battery, you will create a magnetic field. This is what we call an "electromagnet." Remember, only use batteries if you try this, never use a wall outlet--this is much too dangerous!!
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its just a rumor. Magnetism does not induce cancer. We live in a polarised world with a magnetic north and south.
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No there is no substance which can block magnetism except another magnet.  You can block electromagnetic energy quite easily depending on the strength.