Monday, 11 May 2015

Modelling ancient and modern magnetic fields

New Earthlearningidea - 'Human magnets!' This involves using your pupils to model ancient and modern magnetic fields.
Iron-rich minerals in igneous rocks, such as magnetite, may become magnetised as the rock crystallises from the molten state, and then cools down below a critical temperature. This temperature is known as the Curie Point. The direction of magnetisation is induced in the solid rock and records the direction of the magnetic field of the Earth, at that place and at that time.
The activity can be used to aid the understanding of remanent magnetisation in rocks. This in turn provides evidence of past magnetic fields of the Earth and is of great value in demonstrating the former latitudes of the continents, before their plate tectonic movement.
Other good ideas to teach the Earth's magnetism can be found on our website.

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