Post-credits corner from Time Travel Girl, episode 2, on how earth's magnetic field supposedly works, and the curie point.
Here's a small subtitles correction: The currently most widely accepted theories suggest that electric current produces a "magnetic field", not a magnetic charge (the character only says that magnetic properties emerges from it). There still hasn't been any evidence that magnetic monopoles exist, which would in turn make magnetic charges possible. So far, we could only find them in packs of North+South poles (no charge, as there's always one north pole for each south pole).
For better understanding of the topic, take a couple of physics courses on your graduation :)
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