Geology

[equalsmcsquared.livejournal.com]

Good morning, everyone. Coffee and doughnuts are next to the roll sheet. Please note that I will be giving our final exam next Monday and it will be cumulative. If you have missed any quizzes or labs to date, it would be a very good idea to make them up.

Any questions?

All right. Today we will be discussing the Earth's magnetic field.

Magnetic fields are produced by the motion of electrical charges. For example, the magnetic field of a bar magnet results from the motion of negatively charged electrons in the magnet. The origin of the Earth's magnetic field is not completely understood, but is thought to be associated with electrical currents produced by the coupling of convective effects and rotation in the spinning liquid metallic outer core of iron and nickel. This mechanism is termed the dynamo effect.

Rocks that are formed from the molten state contain indicators of the magnetic field at the time of their solidification. The study of such "magnetic fossils" indicates that the Earth's magnetic field reverses itself every million years or so (the north and south magnetic poles switch). This is but one detail of the magnetic field that is not well understood.

Comments

[leeadama.livejournal.com]

Lee takes notes and sips on his coffee.

[12parseckessel.livejournal.com]

Han slinks in, still in the too-large flight jacket. Signs in, snags a couple doughnuts, takes a seat and takes notes.





[[ooc: what you're seeing is a curvy 5'6" brunette in jeans, a blue sweater, boots and a flight jacket that's a couple sizes too large for her.]]

[sensethevisions]

Phoebe signs in and grabs a cup of coffee.

[pure-blooddraco.livejournal.com]

Draco grabs a coffee and sits down in his usual seat. He takes very good notes as OMG he failed his quiz last week. And he's so darn happy that he's beautiful again.

[teen-twin.livejournal.com]

Connor signs in, grabs a cup of coffee and takes a seat, oen in hand and ready to take notes.

[bridge-carson.livejournal.com]

Bridge signs in, grabs some coffee, and sits down. He dumps several packets of sugar in before getting out his book and taking notes.

[miss-thomasina.livejournal.com]

Thomasina signs her name to the roll sheet and takes her seat. The talk of a final exam has her taking even more careful notes than she usually does.