physique question #66
Erin Price (Genre: femelle, Àge: 17 années) de l'Internet sur 16 septembre, 1999 demande:Q:
Comment est-ce que je peux démontrer le rapport entre le magnétisme et les organizations ?
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There have been many studies on the effects of magnetic fields on organisms, from bacteria and algae to birds, fish, and mammals. Some of these are discussed in Chapter 15 of Driving Force: The Natural Magic of Magnets and the references in the back of that book. Some bacteria actually have enough magnetic material inside their bodies that it serves as a compass and aligns their bodies with any magnetic field they are exposed to, including the earth's field. Many other animals have been shown to be able to sense the presence and orientation of magnetic fields, but how they do it and whether it is important to them, for example for navigation, is not very well understood. In some experiments, scientists have exposed the animals to magnetic fields produced by electromagnets and observed whether or not the animals tend to orient themselves in particular directions with respect to the direction of the magnetic field. Such experiments are of course easier with smaller animals than with larger ones, because the larger the animal, the larger the electromagnets must be. Of course, if the animals are small enough, like the magnetic bacteria, you can even use simple permanent magnets to produce a magnetic field for such experiments.