Discovering Static Electricity
Later, other experimenters discovered that other substances, such as diamonds, also attracted light objects the same way amber did. These substances are called insulators. They also discovered that other substances, such as copper, silver, and gold, did not attract anything, no matter how long the object was rubbed and no matter how light or heavy the other object was. These are called conductors because they let electricity flow through them.
Around 600 BCE, in Greece, a mathematician named discovered that amber rubbed with animal fur attracted light objects. Even though other people may have noticed this before, Thales was the first to record his findings. We don't have his writings, but from other people's reports of his work we can guess at his experiments. We think that Thales noticed static electricity from polishing amber with a piece of wool or fur. After rubbing the amber, which created a static electric charge, other light objects such as straw or feathers stuck to the amber. At this time, magnetism was confused with static electricity.
Direction and Magnetism
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About 300 years after Thales, a Chinese general named Huang-ti was supposed to be the first to use a lodestone as a compass. He might have had a polished piece of lodestone on a piece of wood so polished the stone could easily have turned to always point north. Another version of the story suggests that Huang-ti had a lodestone in a floating bowl. The lodestone would force the bowl to turn with it to face north. Chinese military commanders during the Han dynasty (206 B.C.E. to 220 C.E.) used compasses.
Compasses were used by generals and magicians (who had to find the right places for temples or burial sites) for hundreds of years before they were used on ships. Lodestones were not used for ship navigation until the 1200s, when Chinese navigators began to use a ship's compass.
Many doctors during the time of Queen Elizabeth I of England (the late 16th century) were interested in magnetism. They thought magnets might have healing powers for the human body. William Gilbert invented a lightweight tool called a versorium that looked like a compass but didn't use a magnetized needle. The pointer was balanced and would spin in reaction to magnetic attraction even if there wasn't enough force to lift a light object. Nowadays we use a modern version of the versorium called the electroscope to study atomic particles. Gilbert also made up the term electricity. He called objects that attracted his versorium electrics and those that didn't attract the tool nonelectrics.
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