14 Magnetism

If a bar magnet is broken in the middle, two parts are produced:

One part remains entirely a North Pole, the other part becomes a whole South Pole

One part becomes magnetic and the other not

The two parts become magnets with each a North Pole and a South Pole

There is a priori no magnetic monopole. When a permanent magnet is broken, two magnets are produced, each with two poles.

The right answer is iron, cobalt, and nickel. These metals are ferromagnetic at room temperature, that is, they are attracted by a magnet and behave themselves close to it like magnets.

Which scientist born in the 16th century pioneered in the scientific exploration of magnetism?

Giuseppe Moletti (1531–1588)

William Gilbert (1544–1603)

Everard Digby (ca. 1550–ca. 1605)

The right answer is William Gilbert. His main work entitled De Magnete, Magnetisque Corporibus, et de Magno Magnete Tellure (About the magnets, the magnetic bodies and the great earthly magnets) appeared in 1600. Giuseppe Moletti worked on the Gregorian calendar reform. Everard Digby published in 1587 the first scientific (biomechanical) book on swimming (De arte natandi).

The right answer is Tesla, Newton is the unit of power, Pascal is the unit of pressure. The photo shows a proton magnetometer from 1967.

The correct answer is neutron stars, the so called magnetars, which form magnetic fields with strengths of more than 100 billion tesla. By contrast, the strength of the magnetic field on the surface of the Sun is on average a quarter of Tesla. The Earth’s magnetic field is approximately 2 to 5 ten thousandths of a tesla.

The right answer is neodymium-iron-boron magnets, reaching field strengths of up to 1.6 Tesla.

The correct answer is magnetite, which is already mentioned in the Chinese literature of the 4th century B.C. The Roman poet Lucretius (1st century B.C.) first named the attractive stones according to their Greek origin in the writings De Rerum Natura (On the Nature of Things). Magnetite is made of iron oxides, but magnesite is a magnesium-containing mineral, whereas magnetorite does not exist.

The right answer is for Divination. The first compasses were made of magnetite, as probably this spoon, and were used for divination purposes, for example to harmonize places according to the principles of Feng Shui... Only in the Song dynasty, around the year 1040 were compasses used for orientation on land and later at sea.

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