Properties of magnets
Moving electric charges generate magnetic fields
- In permanent magnets (ferromagnetic materials), magnetic fields due to electrons moving about nuclei & those due spin of electrons align & amplify each other
When heated, ferromagnetic materials loose their magnetism at a temperature called the Curie temperature
- Curie temperatures for ferromagnetic minerals are 200-700°C; minerals & rocks melt at 1000°-1400°C
When cooled back below their Curie temperatures, ferromagnetic materials will reacquire their magnetism parallel to the ambient magnetic field
- Thermal remanent magnetism = reacquired magnetism parallel to the ambient magnetic field