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Out of the some $$117$$ elements known in the world, three are special. Cobalt, nickel and iron have a special arrangement of electrons that causes them to have a magnetic field. All permanent magnets are composed of one or a combination of these metals. Magnetic fields are measured in either tesla, $$\text{T = Vs/m}^{2}$$, or gauss, where $$1\text{ G} = 10^{-4}\text{ T}$$.