Magnetic Dynamo Theor3

Magnetic Dynamo Theor3 - interior can be made to swirl...

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Magnetic Dynamo Theory Planets do not have giant bar magnets in their cores, so what produces the magnetic field? Recall from the beginning of the Electromagnetic Radiation chapter , that a magnetic field can be produced by circulating electrical charges. A theory called the magnetic dynamo theory says that the magnetic field is produced by swirling motions of liquid conducting material in the planet interiors. Materials that can conduct electricity have some electrical charge that is free to move about. Such materials are called metallic and are not necessarily shiny solids like copper, aluminum, or iron. Jupiter and Saturn have a large amount of hydrogen that is compressed so much it forms a liquid. Some of that liquid hydrogen is in a state where some of the electrons are squeezed out of the atoms and are free to move around.
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A moving charge will produce a magnetic field. The liquid conducting material in a planet's
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Unformatted text preview: interior can be made to swirl about if the planet is rotating quickly enough. The faster a planet rotates, the more the material gets stirred up and, therefore, the stronger the generated magnetic field. If the liquid interior becomes solid or if the rotation slows down, the magnetic field will weaken. So in summary what a planet needs in order to produce a strong magnetic field is (1) a liquid conducting (metallic) interior and (2) rapid rotation to get the conducting material moving about. For the terrestrial planets plate tectonics may also play a role. Plate tectonics cools the planet's mantle creating a large enough temperature difference between the core and mantle to produce convection in the metallic core needed to make a magnetic field. Let's see how this theory explains the presence or lack of a magnetic field on some of the planets:...
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This note was uploaded on 12/15/2011 for the course AST AST1002 taught by Professor Emilyhoward during the Fall '10 term at Broward College.

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Magnetic Dynamo Theor3 - interior can be made to swirl...

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