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Thread: Permant magnet??

  1. #1 Permant magnet?? 
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    There are some definitions of a permant magnet on the net, but they are different from each other.

    Can anybody explain it to me or are there one who knows any scientists within the magnetic-field area??



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  3. #2 Permanent magnet 
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    To define the term Permanent magnet you need to confirm clearly what you mean.

    One definition is : Magnetism is retained after magnetized by electrical current. So is a residual magnetism, but very strong residue. A permanent magnet does not generate heat, but the magnetism reduces by surrounding heat. A permanent magnet eventually will be de-magnetized by operation over time.

    So many factors affect the conditions for what people refer as permanet magnetism.

    In iron sub currents related to motion of electrons in domains within the metail are considered as the reason magnetizm remains within iron or similar metals.

    Whilst many people may consider aluminium as being non magnetic - If aluminium is moved within a magnetic field current flows within the aluminium and a magnetic field is induced. This effect was used in controlling the speed of quality transcription record turntables around the 1960- 1970s.

    The earth is in motion within the cosmos - so it is not surprising the earth also has a magnetic field that is present in the earths physical structure.

    I hope this answer helps your understanding of the question's you have.

    David


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  4. #3 Thanks. 
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    Thanks David. It helps me to better understand the meaning of the words.
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  5. #4  
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    In common usage the definition is very simple. It is an ordinary magnet, like what you have sticking to your refrigerator door. The other kind of magnet is an electromagnet. The magnetic field of an electromagnet goes away when you turn off the current, but the magnetic field of a permanent magnet is always there.
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  6. #5  
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    But doesn't the magnetfield weaken over time or if another magnetfield i nearby??

    Because - then it is not a permant magnet.
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  7. #6  
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    Quote Originally Posted by future_scientist
    But doesn't the magnetfield weaken over time or if another magnetfield i nearby??

    Because - then it is not a permant magnet.
    Yes, if you want to split hairs, but I'm just telling you what electrical engineers mean when they talk about permanent magnets. For example a permanent magnet generator will contain a permanent magnet as I have described, not some theoretical eternal magnet.
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  8. #7  
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    oh okay. The reason that i am asking is that I might use permant magnets to a big school project, if they are permant, and if they arn't then i can't use them. But thanks every much for the information.
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