The story of Franklin and the lightning rod

1one day in June, 752, in the suburb of Philadelphia, USA, it was covered with dark clouds and thunder and lightning. On a wide lawn, two people, an old man and a young man, are flying kites with great interest. Suddenly, a flash of lightning cut through the clouds and drew a "Z" in the sky. Then there was a clear thunder, and the rain poured down like a ladle.

The old man shouted, "William, stand in the straw house over there and tighten the kite string." At this time, lightning flashed one after another, and the thunder was louder and louder. Suddenly William shouted, "Dad, look!" " "The old man looked in the direction pointed by his son, only to see that the original bare and taut hemp rope suddenly burst into anger, and those tiny fibers stood up straight. He shouted happily, "It's coming!" While telling his son to be careful, he slowly approached the copper key attached to the hemp rope with his hand. Suddenly, as if he had been pushed, he fell to the ground and was numb. Without considering the pain, he got up from the ground and connected the Leyden bottle he had brought with him to the bronze key. There is electricity in this Leyden bottle, which releases electric sparks. It turns out that the sky electricity and the earth electricity are the same! He and his son took the Leyden bottle home like a treasure.

The people who seized Sky Power were Franklin and his son William. Franklin was born in the United States on April 7th, 1706. When I was a child, my family was poor and had no money to go to school, so I worked as an apprentice in the printing factory opened by my brother. However, with his cleverness and unremitting efforts, he made many inventions in his life, and he was the originator of electricity. He is not only a great scientist, but also an outstanding politician and diplomat. He was one of the founders of the Declaration of Independence and the first American ambassador abroad.

After the kite experiment, Franklin wrote a paper about the similarity between lightning and electricity, expounded the essence of lightning, and put forward the idea of making lightning rods to protect buildings from lightning. However, when his paper was read at the Royal Society, some people responded with contempt and ridicule. However, science will eventually overcome ignorance. 1756, the Royal Society awarded Franklin the title of full member of the Royal Society.

The lightning rod invented by Franklin was all the rage and spread to Britain, France, Germany, Europe and America. But when it arrived in England, a strange story happened.

1727, a committee was set up in Britain to discuss the countermeasures of gunpowder warehouse being struck by lightning, and Franklin was appointed as a member. However, it is controversial whether the shape of the top of the lightning rod is pointed or round. Some people take it for granted that a round head is good, but Franklin insisted on using a pointed lightning rod, which was finally adopted, so all lightning rods were made into pointed lightning rods. However, four years later, the American War of Independence broke out, and 13 states united against British colonialism, and Franklin was certainly the first to bear the brunt. This angered King George III of England. Because Britain and the United States are separated by the ocean, the king of England is beyond his reach. In a rage, he ordered all the pointed lightning rods in palaces and bomb warehouses to be smashed and replaced with round ones, and summoned John pringle, chairman of the Royal Society, to declare that round lightning rods are safer than pointed lightning rods. Pringle was very surprised when he heard this. His honest scientific conscience made him refuse the king's request: "Your Majesty, many things can be done according to your wishes, but you can't do things that go against the laws of nature!" Although pringle was removed from his post, the lightning rod was pointed at.

So, why is the pointed lightning rod better? This should start with the relationship between the shape of conductor and its surface charge distribution. Where the conductor surface is seriously curved, such as the convex tip, the charge density is high and the electric field in the nearby space is strong, which ionizes the originally non-conductive air and turns it into a conductor, thus causing tip discharge. At night, I saw a green halo around the high-voltage line, which was a weak tip discharge. Lightning is a large-scale spark discharge phenomenon. When two clouds with different charges are close to the ground or charged clouds are close to the ground, spark discharge is easy to occur because of the extremely high voltage. When discharging, the current can reach 20,000 amps, and the temperature where the current passes can reach 30,000℃. Once this discharge is formed between clouds and buildings or other things, lightning strikes are likely to occur. If a lightning rod is installed on a high-rise building, once a charged thunderstorm cloud is encountered over the building, the tip of the lightning rod will produce a tip discharge to avoid a strong spark discharge between the thunderstorm cloud and the building, thus achieving the purpose of lightning protection. If the top of the lightning rod is round, there will be no tip discharge, and the lightning protection effect is far less than that of the pointed lightning rod.

Ford's story

Ford, a famous car king, helped his father work on the farm since he was a child. When he 12 years old, he conceived in his mind a machine that could walk on the road, which could replace animals and manpower. However, his father asked him to work as an assistant on the farm, but Ford firmly believed that he could become an excellent mechanic. So, he spent one year completing the mechanical training that others spent three years completing, and then spent two years studying the principle of steam, trying to achieve his goal, but without success. Then he devoted himself to the research of gasoline engines and dreamed of building a car every day.

Ford's creativity was appreciated by the great inventor Edison, who was invited to be an engineer in Detroit. After ten years of hard work, 29-year-old Ford successfully built the first car engine. In today's America, every family owns more than one car on average; Today, Detroit has become one of the largest industrial cities in the United States. Of course, it used to be Ford's wealth capital.

Philosophical appreciation:

Everyone can succeed, and everyone can create miracles. But in real life, many people failed to succeed and did not create miracles for three reasons:

One is that some people dare not even think about it.

Secondly, some people think about it but don't necessarily do it.

Third, some people thought about it and did it, but failed to stick to it.

It must be admitted that Ford is a passionate young man who dares to think and do, and the most commendable thing is that he can persist. There is a saying in Augmentation: Ten years of cold window, no one cares, once it becomes famous, it is known all over the world. Those who can study hard and practice hard for ten years on the way to school will certainly succeed in their studies and stand out from the crowd. Perseverance is the secret of success.

Archimedes

Archimedes (287 BC-2 BC12) was a great mathematician and mechanic in ancient Greece. Born in Syracuse, Sicily, died in the same place. Alexander studied with Euclid's students in the cultural center at that time, and later kept close contact with Alexander's scholars, so he was a member of the Alexandria School. Later generations spoke highly of Archimedes, and often listed him as one of the three mathematicians alongside Newton and Gauss. His life is not recorded in detail, but many stories about him are widely circulated. It is said that after he established the lever law of mechanics, he once issued a magnificent statement: "Give me a foothold and I can move the earth!" " "

King Shiloh of Syracuse asked the goldsmith to make a crown out of pure gold. Because it was suspected that there was silver in it, Archimedes was asked to identify it. When he entered the bathtub to take a bath, the water overflowed outside the bathtub, so he realized that although the weight of objects made of different materials was the same, the discharged water would be different because of their different volumes. According to this truth, it can be judged whether the crown is adulterated. Archimedes jumped up with joy and ran home naked, shouting, "Found it! Eureka! " (Greek means "I found it") In his famous book On Floating Bodies, he summed up the basic principle of hydrostatics, that is, the weight of an object in a liquid is equal to the weight of the liquid, and later became famous for Archimedes' principle.

During the Second Punic War, the Roman army besieged Syracuse, and Archimedes devoted all his intelligence to serving the motherland. Legend has it that he grabbed the enemy's boat with a crane and smashed it to pieces; Invent wonderful machines and fire big stones and fireballs. There are also some books that record that he burned enemy ships with huge fire mirrors reflecting sunlight, which is probably an exaggeration. In a word, he tried his best to give the enemy a heavy blow. Finally, Syracuse Gui was betrayed by spies and ran out of food. Archimedes died unfortunately at the hands of Roman soldiers.

Archimedes' handed down works mainly include the following works. On the Ball and the Cylinder is his masterpiece, which contains many great achievements. Starting from several definitions and axioms, he deduced more than 50 propositions about the area and volume of spheres and cylinders. His thought has epoch-making significance and is the pioneer of modern integral calculus. He has many other inventions. No ancient scientist, like Archimedes, combined skillful calculation skills with strict proof, and closely combined abstract theory with concrete application of engineering technology.

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