what is the material of speakar magnet?
300439
This question is miscategorized.\n\nSpecial Education refers to the education and parenting of children with special needs.
281985
http://www.garp.com/frmexam/BuyStudyMaterials.asp
512462
By "natural magnet", I assume you mean the mineral magnetite (Fe3O4).  At room temperature (and at temperatures below ~850 K) magnetite is a semiconductor, above ~850 K, it is behaves like a metallic conductor.\n\nThe resistivity of pure magnetite at room temperature is about 0.33 ohm*meter, which is close to that of pure germanium (=0.46 ohm*meter).  "Good" conductors of electricity (like metals) have resistivities less than about 10^-6 ohm*meter, while good insulators have resistivities greater than aabout 10^9 ohm*meter.  As you can see, at room temperature, magnetite lies somewhere in between.
359816
http://www.vrml.k12.la.us/mike/Intech2/learning_about_magnets.htm\n\nCHECK IT OUT
1090476
Iron (like steel and certain alloys) contains atomic magnets or dipoles which can line up their 'magnetic axes' in a preferred direction.  In the magnetized state, all the magnetic axes will point in one specific direction, by which the iron filling will show polarity and hence be a magnet itself.\nWhen you heat the iron fillings, the high temperature makes the atoms to vibrate with increasing energy and this disturbs the dipoles and so the resultant magnetic axes point in their 'preferred' random directions, which keep changing due to the extra energy. If the iron fillings were magnetized before heating, all the magnetism would be lost. Magnetizing them after heating will not align the vigorously vibrating atomic magnets and rapidly changing magnetic axes.
537198
See the listing of suppliers given in the source below.  If you want to do magnetic separation, you'll want multi-domain particles, which means using particles *larger* than about 100 nm (depending on the material).
230240
No. Things only respond to magnetic fields if they are paramagnetic, meaning they have an extra lone pair of electrons that aren't tied down. Glass is SiO2 (silicon dioxide, better known as quartz and sand), which doesn't have the lone pair required.
216587
It's been said that any sufficiently advanced science is indistinguishable from magic.  Let's try a few of the older but lesser known ones:\n\nAbout 15/20 years ago material science came up with two new materials which are rather interesting.  The first is Aerogel, a solid which is lighter than air - it will float at room temperature.  The second is called Seagel which is about as heavy as plastic but is as strong as steel, it can be either transparent or opaque and your choice of electrially conductive or not.\n\nHow's that for a start?
304336
No there is no substance which can block magnetism except another magnet.  You can block electromagnetic energy quite easily depending on the strength.
1092387
The closest magnetic source.
1029513
has to be metal, preferably in several sheets not touching each other. Wood and plastic do not stop magnetic field.\n\nThick piece of lead would definitely work, and is completely safe (as long as you do not drop it on your foot and wash your hands afterwards)
357714
Some types of metal and other magnets.
206699
Depends on what you mean by block the effects. Stainless is transparent to magnetism much like glass to a flashlight, ferrous (normal) steels will "pipe" the magnetism to a new direction, and Aluminum will scramble the magnetism.\n\nThis scrambling of the magnetism by aluminum is used by modern roller coasters as a braking device. Powerful magnets are on the vehicle and the aluminum is attached to the guideway. When the two get close toghether the scrambled lines of magnetism have the effect of removing energy from the moving vehicle (slowing it down) and heating up the aluminum.\n\nTry this: while not in the presence of steel, hold a powerful magnet in your hand. Swing your arm back and forth, note how freely your hand moves. Now swing your arm close to, but not touching a plate of aluminum. When you get near the aluminum your arm will slow down.\n\nNow set the magnet on the aluminum. It does not stick like it would to steel. The braking effect only occurs when the magnet and aluminum are moving relative to each other.\n\nAt high speeds this magnet-aluminum relationship builds up much like water causes a tire to hydroplane. This website wants to use this effect to build high speed railways: http://www.magplane.com
800493
Pounding on your workbench can put very high shock loads throughout.  In extreme cases shock waves can cause pieces of solid steel to separate (called spalling).  Further, as other answers mentioned, magnets tend to be brittle.  This is not because they are made of cheap iron.  Modern rare earth magnets are made using a complex sintering process where particles are compressed at slightly elevated temperature to hold them together.  They are notoriously brittle.  Finally, internal forces caused by the fields inside the magnet actually tend to force the magnet apart, splitting it from pole to pole.  Put this all together and poof - one magnet becomes several.
1097908
Iron, cobalt and nickel can be magnetic. They can be made to have polarity. Poles that are alike repel and poles which are not alike attract. A magnet will attract all of them if they are not polarized. If they are polarized, a magnet will attract or repel according to the polarity.\n;-D
95839
One of my vendors is Magnet Applications --
531203
prooly need ifrared thingy\ntry a industrial magnet