How come the earth has magnetic field?
I believe that current theories have to do with motion within the earths molton core.
May be it was found by the nature of the iron made Magnets
The most widely accepted theory that explains this is called the self-exciting dynamo theory. It postulates that the earth rotating in its' magnetic field induces a current within the core. The composition of the core has large amounts of iron in it. Because the iron is hot, being heated way above the curie temperature (which is about 760° C for iron) it can't be magnetized, but since a current flows, inevitably a magnetic field must coexist. I suppose this is the reason why the earth's magnetic field is weak being about 0.5 gauss (0.00005 tesla).
I don't know, the theory doesn't seem to explain the initial origin of this magnetic field, rather just how it lives.
You can do a google search on the subject and probably find out more.
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Aha...only Iron theory can't be acceptable...because it doesn't explain gravitational field
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Last I heard iron had mass.
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Hu! But I wanted to tell that...why we are on earth for it's magnetic field or gravitational field ???
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You're asking why we don't float off? The gravitional field. If the magnetic field suddenly shut off we'd be fine except some people would get lost and maybe we'd have to worry more about getting cancer.
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Hah! You are right? But is there is quetion about Magnetic Field then we must know where the Gravitational field comes from ???
Everything has magnetic field
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