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Question: How come magnets stick to iron and we have iron in our body, but magnets don't stick to us?
Iron belongs to a specific class of metals called Ferromagnetic Materials, Iron, along with cobalt and nickel behave the same way when placed next to a magnet or in a magnetic field. Actually, magnets are made up of jillions of tiny magnets having magnetization or magnetic forces, known as domains, lined up with their north poles in one direction and south poles in the opposite direction. In ordinary ferromagnetic materials (like iron), these tiny magnets are scattered every which way, and their magnetic fields cancel each other out. Enterprisingly, when we put them close to a magnetic field (i.e., near magnet) these tiny magnets line up parallel with one another and the material as a whole become magnetized (like a magnet itself) and produces a strong magnetic field. This magnetic field represents a great deal of energy and is responsible for the force generated between metals like iron and a magnet.
Conversely, such magnetic domains aren't formed in the human body. A well-nourished human body contains only about 4 to 5 grams of iron. Of this, approximately sixty percent is part of the hemoglobin, needed to carry oxygen through the blood. The remainder is contained in ferritin complexes that are present in various body cells. Unlike metallic iron, our body not only contains non-metallic phases (iron ion making chemical bonds with organic molecules) but also a very low concentration. The presence of iron complexes in floating media and in low concentration ceases its inherent strength of making tiny magnets or domains and hence, magnetic power. Even if a strong magnetic field were applied, our body wouldn't experience a substantial magnetic force, regardless of the excellent sources of iron we ingest such as raisins, avocados and multivitamins.
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