ERTH 2415 Lecture Notes - Lecture 1: Ionosphere, Coronal Hole, Solar Flare
28 Aug 2018
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Document Summary
Faraday"s law of electromagnetic induction in the laboratory: magnetic field variations induce an electrical current in a medium, the induced current creates its own magnetic field. Electromagnetic surveying: prospecting technique, controlled experiment, an artificial varying magnetic field induces currents in subsurface ore bodies. Metallic: these currents generate a magnetic field recorded at the surface from the air. Geomagnetic hazards: extreme variations of the earth"s magnetic field can have a significant impact on technological systems, geomagnetic effects observed for 150 years, disturbances on the telegraph first simulated investigations. Earth"s magnetic field: superposition of signals from. Internal geomagnetic field: slow variations, magnetic field in ottawa 56000 nt, over a few years: magnetic poles wander around the geographic poles, every few hundred thousand years: North and south magnetic poles flip polarity. External geomagnetic field: disturbances affecting technological systems are caused by variations of the external geomagnetic field, short duration (hours, days, driven by solar activity.
