"Look at this bar magnet. I tied a wire to the center of it and let it hang. After it came to rest, the end pointing south was called the south pole of the magnet. The end pointing north One end is called the north pole of the magnet. Then I label the north and south poles on both ends of it. Qingque, you also follow the steps I just took and label the other magnet with the north and south poles!"
In Zuifengxuan, Li Zexuan was carrying a bar magnet and was doing the most basic physics experiments for the four of them.
"Okay, okay, Tai will try it too!"
Li Tai had read a lot of the Four Books and Five Classics, but he had never done any real experiments. He had just been watching Li Zexuan having fun on the sidelines, and he had already been gearing up, feeling hungry and thirsty. When he heard this, he immediately rushed forward.
Li Zexuan smiled and let the little fat man play by himself. He went to get two small pieces of paper and was about to paste the "N" pole and "S" pole on the magnet in his hand. He was suddenly startled. This was In the Tang Dynasty, how did the ancients know "North" and "South"? If you mark them with "N" and "S", who knows what they mean
In desperation, he shook his head and could only write "N" and "B" at the two ends of the North and South Pole, just use the pinyin initials of South and North! Oh, what trouble! Many scientific terms and terms in later generations have various English abbreviations. What should we do? Thinking of this, Li Zexuan couldn't help but feel a headache. It seemed that there was still a long way to go to improve Datang's technological level!
"Sir, Tai also found the South Pole and the North Pole, eh~? Sir, what does the word you marked mean?"
Li Tai's hands-on skills were pretty good, and he found the north and south poles of the other magnet in a short while. However, when he looked at the two letters marked by Li Zexuan, he suddenly became a little confused.
"Qingque, do you still remember the pinyin? These N and B are the pinyin initials of south and north. For the convenience of marking, we will use these two letters to replace the north and south poles in the future!"
Li Zexuan couldn't help but feel lucky for his wit just now. Otherwise, how would he explain it if he had written an "N" and an "S".
"Oh~! I see, it's very convenient for Tai to say this, sir!"
Li Tai suddenly understood, and then he followed suit and marked the north and south poles of the magnets in his hands. At this time, Li Zexuan took the two magnets in his hands, looked at the four of them, and said:
"Next, I'm going to tell you a very important theorem, that is, magnetic poles of the same sex repel each other, and magnetic poles of opposite sex attract each other. If you don't believe it, you can try it yourself and see if this is the case!"
"Is this possible? Let me try!"
Li Yu took two magnets and started the experiment. Although she didn't know Pinyin, she could still tell whether the two letters were the same.
"It's true! Sir, why is this? And what does this have to do with the compass indicating the direction?"
After Li Yu played with the magnet twice, she got the result predicted by Li Zexuan, and then she asked.
"Why do same-sex repels and opposite-sex attract? You can think about this later. Of course, you can also understand it as the relationship between people. Generally, it is a man and a woman who get married. You have never seen a man get married. Are you getting married to a boy or a girl to a girl?"
Li Zexuan couldn't explain this problem clearly at the time. At that time, his physics teacher just said it was a theorem and asked everyone to remember it. As for why people of the same sex repel each other and opposite sexes attract, he didn't know. He could only say one word. If it doesn’t work, just drive!
"Puch!"
Li Yu smiled and said, "Sir, this is really interesting!"
"Ahem, as for what this theorem has to do with the compass, I can only say that it has a lot to do with it. In fact, the earth can be regarded as a big magnet. One of its poles is near the geographical north pole, which can also be called the geomagnetic south pole. One pole is located near the geographical South Pole, which is the geomagnetic North Pole. According to the principle of like-sex repulsion and opposite-sex attraction, our magnets and magnetic needles can point exactly in the north-south direction under certain conditions."
Li Zexuan began to popularize the knowledge of the geomagnetic field to them. It was the first time for several children to hear such a novel theory, and their eyes widened.
"How is it possible? How could the ground we are standing on be a magnet?"
Li Tai murmured to himself, with a look of disbelief on his face. These shocking remarks simply overturned his world view.
"hehe!"
Li Zexuan smiled and didn't say much. He walked to the tables nearby and started drawing. A compass truly used for navigation cannot be so crude and crude, with no technical content.
In fact, the core part of the compass, in addition to the magnetic needle, is its central axis. It is necessary to consider not only the balance of the needle, but also the friction during rotation.
Li Zexuan designed the shaft into a stepped shaft. He drilled a hole slightly larger than the diameter of the thin end of the stepped shaft at the center of gravity of the magnetic needle. After passing the magnetic needle into the thin shaft, he tried to deform the thin shaft end, riveted the magnetic needle to the thin shaft, and controlled The deformation of the thin shaft end prevents the magnetic needle from being riveted. At this time, the magnetic needle can rotate around the thin axis but cannot break away from the thin axis. As for the cover of the compass dial, it can only be made of glass.
I was lazy and didn't make glass before, but I didn't expect that I still can't get around glass now, so let's make glass by the way this time!
Thinking of this, Li Zexuan raised his head and ordered:
"Sambo, go and invite Uncle Fu over!"
"Yes, Master!"
Sanbao responded and hurriedly ran out of the courtyard to find Uncle Fu.
After a while, Uncle Fu came in and asked, "Master, are you looking for me?"
"Well, Uncle Fu, please see if this thing can be built first."
Li Zexuan handed the drawings of each part of the compass to Uncle Fu and said.
Uncle Fu took it, looked at it carefully, pondered for a moment, and finally nodded and said: "It should be possible, but it is very troublesome. There are many fine small parts in the thing you drew, Master. If you want it to be done accurately, To come out, the craftsmen who are more than ten years old must do it themselves!"
When Li Zexuan heard this, he patted his head and almost forgot that some components in this compass are almost equivalent to a small precision instrument. For a modern industrialized society with various lathes and machine tools, it only takes a few seconds, but For the current state of the art that relied entirely on manual polishing in ancient times, it was really a big difficulty.
"Uncle Fu, please organize a group of experienced craftsmen as soon as possible and ask them to put down their work and concentrate on making a batch of compasses. Oh, I forgot to tell you. This thing is called a compass. Your Majesty is in a hurry. Yes, the imperial court mainly relies on this thing to identify the direction in the vast sea when the navy goes south. Let the craftsmen hurry up. If you make one more, you may save the lives of an extra boatload of people! "
Li Zexuan said seriously, if there is a problem, it will be difficult for customer service. Although there was no modern craft equipment in ancient times, there were so many skilled craftsmen. Many ancient handicrafts or buildings cannot be made by modern people even if they rely on machinery.
Uncle Fu previously thought that Li Zexuan came here today just like before, just wanting to make some novel gadgets for himself, but he didn't expect that Li Zexuan came with such an important task today. After hearing this, he quickly looked serious. road:
"Don't worry, young master, everyone in the workshop will work together in the next few days to make a batch of compasses!"
… … … …
First update!
Thank you A for the reward of seeing you again and loving you like never before!
(End of chapter)