LECT13_191196

LECT13_191196 - The N pole of a magnet got its name because...

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
The N pole of a magnet got its name because it points roughly towards Earth's north pole. It points towards NE Canada, since that's the Earth's South magnetic pole. Earth’s B-field is actually upside down, and the dipole axis is offset slightly (~11º) from Earth's rotation axis.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Earth's magnetic field has a vertical component at the surface: Points upwards in southern hemisphere. Points downwards in northern hemisphere. Parallel to surface at magnetic equator. Source: Current/ convection in hot Fe liquid core
Background image of page 2
Basalt is expelled from volcanoes and cools, and the B-field becomes imprinted. Mid-Atlantic Ridge shows that B-field direction changes every ~0.1–1 Myr
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Mars Mars: No ‘global’ B-field like Earth’s (no internal dynamo?) Mars Global Surveyor (JPL/NASA) (from comicvine.com) Mars Global Surveyor’s magnetometers: very strong crustal fields: Older crust is magnetized much more strongly than newer crust Indicates that very strong global magnetic fields existed, but only before ~4 billion yr ago
Background image of page 4
Mars’ surface area/ volume ratio (prop.to 4 π r 2 / (4 π /3)r 3 dynamo mechanism faster Moon: also evidence for a B-field that was stronger in the past (from Lunar Prospector mission) Mars Mars Global Surveyor (JPL/NASA) (from comicvine.com) Meteor impacts: crust melts and reforms; any imprinted magnetism is lost
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Units of B-fields Tesla [SI] and Gauss [cgs] 1 Tesla = 10 4 Gauss. Typical B-field strengths:
Background image of page 6
Image of page 7
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 09/30/2011 for the course PHYS 1B taught by Professor Briankeating during the Summer '07 term at UCSD.

Page1 / 22

LECT13_191196 - The N pole of a magnet got its name because...

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online