Exploring the Uses of Magnetism

BACKGROUND:

Discuss the history of magnetism. The ancient Greeks noted magnetism in the mineral magnetite or lodestone. In a Greek myth, a shepherd boy named Magnes, thrust his iron staff into a hole containing magnetite and found to his dismay that he was unable to remove it. (Students can find magnetite if they take a magnet to some beaches and drop it in the sand. What sticks to the magnet is usually magnetite.) Socrates and Plato noted magnetism in some of their writings. It is also said that 2,300 years ago, Ptolemy Philadelphos had a temple at Alexandria made from magnetite so he could suspend a statue in mid-air. His experiment didn't work. Magnetite loses its magnetic quality over time.

Magnetism gets its name from the Magnates, inhabitants of Magnesia and named by the Greeks, where lodestone is very abundant.

Shen-Kua, a Chinese mathematician and instrument maker, was the first person to mention the use of a compass for navigation. He lived from 1030 to 1093.

In 1600, William Gilbert, a private physician to Queen Elizabeth, published a book on magnetism. However, this book was more curiosity than a scientific work.

It wasn't until the late 1700's, that scientists (mainly physicists and mathematicians), began to unravel how magnetism works. In the mid 1800's, the relationship between magnetism and electricity was suggested.

In the 1820's, scientists noticed the connection between electricity and magnetism. Joseph Henry and Michael Faraday established the importance of magnetism in relation to electricity. In 1873, James Maxwell wrote a book which illustrated these discoveries. These discoveries led the way for the development of the generator and the motor. The reason that automobiles were not perfected until the 1900's resulted from the fact that the engine was not practical until the end of the 1800's.
PROCEDURE:

After discussing this information with students, have them write an essay on what our world would be like without magnets or motors. Include other details in the discussion about various uses for magnets. Magnets make sound possible in loudspeakers. Magnetic tape provides a means to record and store data. Almost all electrical appliances have magnets. Most of our complicated machines use not only electricity, but also magnetism to operate. Ask students to be creative and to really concentrate on thinking and imagining.

You may want to use the Internet for students to do searches on magnetism.


OBJECTIVES: Investigating the historical development of magnetism. Exploring the uses of magnetism. VOCABULARY: compass electromagnets lodestone magnetite motor MATERIALS: Internet	Students use the internet to explore the history of magnetic substances.