What is the primary cause of the Earth's magnetic field?

╝ A

''The flow of liquid iron generates electric currents, which in turn produce magnetic fields. ''

A planetary core is more than a hot water bottle of lava, it's actually a molten liquid reactor breeding Uranium 233 from Thorium 232 so it's generating some of it's own heat. Mar's is often said to have cooled off but it has had recent volcanism at least 2 million years ago which by geologic time is pretty much now, Mar's mantle and core may be more viscous than Earth's and lack the dynamic dynamo but it's hardly solidified. Obviously a large impact could cause the dynamo to stop spinning, the tidal effects of the Moon ensure that there is always a difference in rotation between the core and the crust as the crust is being slowed down. And of course, time will stop it from spinning but if you're waiting for the mantle and core to cool down, you'll have to wait a much longer time than the life of our Sun.

The answer is A. The Iron revolving around the earths core produces a magnetic field.

Well, ..., the answer is A. Earth's magnetic field is formed by magnetic flux emanating from Earth's rotating magnetic core. Essentially it's one big electro-magnetic motor!

A. Currents in the Earth's core

http://www.pbs.org/wgbh/nova/magnetic/reve-drives....

The Barnett Effect states that a spinning object will spontaneously generate a polar magnetixc field.

The fact that the core of the earth is molten (mostly iron).

It would be a lot easier for use to do your homework for you if you were to just put all the homework questions into one post.

http://en.wikipedia.org/wiki/Earth%27s_magnetic_fi...