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Magnetic fields

#    The strength of a magnetic field is measured in tesla.

#    The strength of Earth’s magnetic field is around 50 millionths of a tesla.

#    A fridge magnet is ^^out?^ 100 times morę powerful than Earth’s magnetic field.

#    Most MRI (Magnetic Resonance Imaging) body scanners in hospitals use a 1.5-tesla magnet

#    The most powerful MRI scanner used on humans has a 9.4-tesla magnet weighing morę than 40 tons!

m The strongest magnets buift by scientists so far have a field strength of around 100 tesla.

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In 2009, scientists atthe Jet Propulsion Laboratory in California were able to make a live mouse float in midair by placing it in a magnetic field 300,000 times stronger than Earth’s!

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580 BCE

Greek philosopher Thales of Miletus writes about the magnetic effects of lodestone

1086

Chinese scientist Shen Kua describes a magnetic compass

1600

William Gilbert, an English scientist, describes Earth’s magnetism

1819

Danish scientist Hans Oersted discovers electromagnetism when he notices that electric currents produce magnetic fields

1821

English scientist Michael Faraday builds the first simple electric motor

1831

Michael Faraday discovers electromagnetic induction—the ability of a changing magnetic field to make an electric current flow in a wire

1906

Pierre Weiss, a French physicist, describes the domain theory of magnetism

1939

German-bom scientist Walter Elsasser suggests that Earth’s magnetism is caused by swirling motions in the liquid part of Earth’s metal core

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The magnet found inside an MRI scanner is extremely powerful

as well as being able to move objects such as scissors, chairs, and oxygen tanks, it can even move a forklift truck across a room.