name two diffrences between permanent magnets and eletromagnets.?
139636
Electromagnets are made out of metal that can easily be magnetized by applying DC voltage. Electromagnets do not occur naturally in nature but are manmade. Their magnetism can be turned on and off.\n\nPermanent magnets occur naturally in nature.
886336
Different metals have different magnetic field strengths.\n\nFor example, neodymium magnets are among the strongest.
80341
regular magnets are natraly magnitised, they maintain their magnetic properties with out aid of an outside force\nelectro magnets use a coil of wire, with a curent passing through it, wraped around a piece of metal to create the magnitism. when you remove the curent, it loses its magnetism.
172938
Electrostatics is the study of static or non time varying electric fields.\n\nElectromagnetics is the more general term applied to the study of electric and magnetic force fields.  Usually most situations deal with time varying currents producing time varying magnetic fields.  Maxwell's equations show us that time varying magnetic fields produce time varying electric fields.\n\nThe rest of electromagnetics is the study of the physical properties of these force fields, how they behave in a conductor, how antennas can radiate these fields, etc.
1514
you must use insulated wire or you will effectivly just short out your power source.  most modern electro-magnets use wire that is insulated with a thin coating of a special varnish.  this allows more winding in a given space.  varnish insulated wire is available from nearly any electronics store or catalog or from any business that rewinds electric motors
359816
http://www.vrml.k12.la.us/mike/Intech2/learning_about_magnets.htm\n\nCHECK IT OUT
1173860
http://www.oz.net/~coilgun/theory/solenoidphysics.htm
789773
let us understand it in a simple way:\n   Suppose you have a magnet as shown below:\n                                [ N ]\n                                [ S ]\n\nBy cutting the magnet centrally, if you  mean cutting it vertically, then we would obtain the following configuration after cutting the magnet:\n                              [N] [N]\n                              [S] [S]\nThat is to say we have resulted in two magnets with polarities as shown above.Now as we all know that like polarities(N-N, S-S) repel and unlike polarities(N-S,S-N) attract, the result follows that the two magnet in above configuration repel each other while they attract when one of them is rotated by 180.\n[When one of the magnet is  rotated (say the second one) the following configuration results:\n                            [N] [S]\n                            [S] [N]\nand hence the result.]
484193
You mean 2 P of a M which is 2 poles of a magnet.
928896
While both have attraction on one side and repulsion on the other side, a magnet can not shout. \nNext: A magnet retains its gloss and colour if stored properly even after ten years.
131979
a soft iron core increases the strength of an electromagnet, because iron a good conductor of electricity, and unlike steel it can be turned on and off, whereas steel is a permanant electromagnet.
483815
Its thro permanent magnets. The traditional maglev used electro magnets on both track and the car but this uses a permanent magnet and uses electromagnet only for propulsion
89147
>>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:
644673
They get cold. \n\nThere are some effects on magnetic properties when you go very cold (search on magnetism AND temperature) especailly for electromagnets. Some things which aren't magnetic start to become so and things which are magnetic become more so. You wouldn`t notice much if you used a home freezer, you need to get much closer to absolute zero.    \n\nMaking it hot has a more important effect. A permanent magnet heated to above its Curie temperature will lose its properties.
128833
Three types of magnets:\n\n-Ferromagnets: Magnets which retain a magnetic field after having been magnetised in a magnetic field.\n\n-Paramagnets: Magnets that only exert a magnetic field when they're in another magnetic field.  They support the magnetic field they're in.  Usually their fields are quite weak compared to the external fields.\n\n-Dimagnets: Magnets that exert a magnetic field when they're in another magnetic field but opposing the field.  (Think: *DI*ametrically opposite).  Again, field intensity created by these magnets typically is very small compared to the external field.\n\nAdditionally, many dimagnetic and paramagnetic materials may become ferromagnetic if they are sufficiently cooled.\n\nPermanent magnets are most often ferromagnetic and will retain their magnetism for a long time even in the absense of a magnetic field.  Over time, however, thermal effects will slowly decrease field intensity, but that takes a long time for permanent magnets.
590620
The difference lies in the nature of the fields. The electric fields can affect every charged particle whether it is static or moving but magnetic field can affect it only if its moving that even not along the magnetic field lines. The force due to electric field follows F=qE and is in the direction of the field itself whereas the magnetic force follows F=q(vxB) and is in the perpendicular direction to the magnetic field and thus causes the charge particle to gyrate around the field lines. Moreover the work done by a magnetic force is zero unlike in the case of an electric force.
274869
Electromagnetic is a term that refers to electric and magnetic fields.  Since they are actually one and the same thing, they are collectively called electromagnetic.