ERTH 2415 Lecture Notes - Lecture 13: South Magnetic Pole, Coronal Mass Ejection, Electromagnetic Induction
17 Nov 2016
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Document Summary
Faraday"s law of electromagnetic induction magnetic field variations induce an electrical current in a medium. The induced current creates its own magnetic field. Variations in the earth"s magnetic field induce electrical (telluric) currents: On electrically conducting networks: telegraph and telephone lines, pipelines, power transmission lines. Record for a few hours to a few days: earth"s magnetic field i. e. magnetometers. A magnetometer is an encased tightly wound coil: telluric currents i. e. electrodes. Electrode is approximately 15 cm in length and is buried in the ground and. Estimate the electrical conductivity in the subsurface (regional scale) contains e-line connections. Controlled experiment: an artificial varying magnetic field induces currents in subsurface ore bodies. These currents generate a magnetic field recoded at the surface or from the air. Estimate the depth, shape and electrical conductivity of subsurface ore bodies: metallic ore bodies are more conductive than the surrounding rocks. Extreme variations of the earth"s magnetic field can have a significant impact on technological systems.
