The discovery of magnetic phenomena of powerful magnets2018-06-07
In the pre-Qin era, our ancestors have accumulated a lot of understanding in this respect. When they are looking for iron ore, they often encounter magnetite, which is a magnet (mainly composed of iron trioxide). These findings were recorded long ago. The earliest records of these discoveries were in several of Guanzi: "There are magnets in the mountains, with gold and copper beneath them."
Other ancient books such as the Shan Hai Jing have similar records. The iron absorption characteristics of the magnets were discovered very early. The masterpiece of Lu's Spring and Autumn Period in the nine volumes was: “Timing irons, or citing them.” At that time, people called “magnetic” as “ci”. They attracted magnets. Iron is seen as a kind mother's attraction to children. He also said: "Stone is the mother of iron, but stone is merciful and merciful. Stones of love can attract his children. Unbeatable stones cannot be attracted." Before Han, people wrote magnets as "cishi". The meaning of loving stone.
Since magnets attract iron, can they attract other metals? Our ancestors made many attempts and found that magnets can not only attract metals such as gold, silver, and copper, but also can not attract bricks and tiles and the like. At the time of the Western Han Dynasty, people had realized that magnets only attracted iron and could not attract other objects. When two magnets are placed close together, they sometimes attract each other and sometimes they are mutually exclusive. It is now known that magnets have two poles, one called the N pole and one called the S pole. The same sex is extremely exclusive and the opposite sex attracts each other. People at that time did not know this truth, but they could still be aware of this phenomenon.
In the Western Han Dynasty, there was an alchemist named Yan Da. He used the nature of magnets to make two pieces of chess. By adjusting the mutual position of the two chess pieces, sometimes the two pieces attracted each other and sometimes they were mutually exclusive. The big name is "battle." He dedicated this novelty to Han Wudi and demonstrated on the spot. Han Wudi was amazed and the Dragonheart was greatly pleased, and he was actually called “General Wu Li”. Zheda made use of the nature of the magnets to create novelties and deceived Han Wudi.
The Earth is also a large magnet. Its two poles are close to the geographic South Pole and the geographical North Pole. Therefore, the magnet on the surface of the earth can turn freely
When moving, it will be repulsive due to homogeneity of the magnets, and the nature of the opposite sex attracts North and South. This principle is not well understood by the ancients, but they are very clear about this phenomenon.