Short video spoiler history: The beginning of modern warfare

Chapter 128 Old-fashioned Telephone

In Jinling City, in addition to Zhang Laosan, many other electrical appliance store owners and bosses have also made up their minds to take the lead and install air conditioners. Many people have even set their sights on becoming students of the Imperial Academy. After all, there are not many literate people in the community, and it is even more difficult to do any research.

[The reason was that the Dragon Boat Festival and the college entrance examination coincided, but college students were not allowed to leave the campus during the holiday. When a group of college students were confused, the Education Bureau came out and said that this was to prevent college students from taking exams for high school students.]

[Hahaha, be careful to prevent college students from taking the college entrance examination for others. Just do it, and no one will say a word.]

[These schools really have confidence in their students. It’s hard for them to pass the CET-4 and CET-6. They are considered good people if they don’t fail.]

[Why are you guarding against him? Just guard against the freshmen from some 985 and 211 universities. There is no need to guard against the rest.]

[Do you still remember the senior from Harbin Institute of Technology? He scored 227 points (out of 750 points), which was barely enough to pass the junior college entrance examination. So do you think your school is better than Harbin Institute of Technology?]

[Haven’t you heard the saying, physical strength peaks in junior high school, intelligence peaks in high school, and appetite peaks in college]

[As for the college students who memorize the six-digit pickup code and forget it three times when walking upstairs and downstairs, it’s really unnecessary]

[What you should be on guard against is college students turning against the Tian Gang and asking high school students to help them take the CET-4 and CET-6. After all, isn't there a precedent there? ]

[On the other hand, I can understand that you might be really afraid that the students in your school will be delayed by that college entrance examination candidate.]

[Hmph, don't worry about it. It's almost the end of the semester. Think about it and try to lower the failure rate in school. You're just doing useless things every day.]

In front of Fengtian Hall.

Zhu Yuanzhang, Liu Ji and others looked at each other in disbelief. Aren't high schools and universities right next to each other? How come after entering university, they all forgot their previous studies like a completely different person?

"Is this Harbin Institute of Technology the one that was on the sanctions list?" Zhu Yuanzhang had some vague memories, but he couldn't remember them clearly. It seemed that the content of the sky curtain was just a joke at that time.

When the people below heard His Majesty's question, they quickly searched through the directory and soon found the list of sanctioned universities.

"Yes, that's true. He is one of the Seven Sons of National Defense." Zhu Yuanzhang understood a little, then asked in confusion: "Students who can attend this school must be outstanding. Why has their knowledge regressed so seriously in just three years?"

Everyone shook their heads in confusion. It was indeed unbelievable that he only scored 750 points out of a full score of 227.

"No wonder he said before that giving Wu Hou 100,000 college students was useless, and he should give 100,000 high school students instead." Someone muttered, and now everyone understood the hidden meaning behind his ridicule.

Zhu Yuanzhang couldn't help blushing when he thought of his previous hope that a college student would travel back in time to tutor him. If a college student really came, it would be useless for him to sleep until 9 o'clock every day. It would be better to have a high school student, who is at the peak of his intelligence.

It is easy to fool people when they are young. What if one day after he passes away, he can pass it on to Biaoer.

Zhu Yuanzhang thought happily for a while, put all these nonsense out of his mind, and then he remembered that after college, it seemed that he would have to choose a specific area to do in-depth research, such as materials science, medicine, etc., which was indeed very different from what he would learn in high school.

Over time, it is reasonable that these contents are forgotten if they are not reviewed for a long time.

Then why do we have to learn so many things in high school that are completely useless in college?
"By the way, there is also the reform of the college entrance examination." Zhu Yuanzhang slapped his head, as if later generations also realized that this situation was not rational, so they carried out reforms. However, it seemed that high school still had to learn a lot of things that seemed completely useless.

The crowd didn't take this matter seriously, they just thought it was a little novel, so they all looked at the comment section.

"The exam starts at nine o'clock, but I can't get up"

"Beware of the real high school bully [狗头]"

《Principal: This kid's swearing is a bit dirty; College student: I think he is right [covering face]》

[I don’t know if you still remember wired telephones. I guess only some rural households or government agencies still have these phones now, and they are rarely seen in other places. Today I will take you to disassemble the wired telephones and their systems from ancient times.]

[Old-fashioned telephones have two tubes, one is called a microphone and the other is called a handset. As the name implies, the microphone is the end where people speak, and the handset is the end where the sound comes out. The microphone and the handset are connected by a pair of telephone wires, one for sending voice and the other for receiving voice, and they both need to be connected to a power source]

[In the old days, the microphone and the receiver were separate, but later they were gradually integrated into one part, like the red curved telephone handle we have seen before, with the receiver on top and the microphone on the bottom]

[Okay, now let's take a look at the structure of the original telephone. The microphone and the receiver are connected by wires.]

[The microphone part has a lot of carbon particles inside. These carbon particles are conductive. You can imagine them as graphite. There is a thin iron diaphragm outside it, and this diaphragm can move.]

[When a person speaks, a sound wave is transmitted. We know that the essence of sound is the vibration of air. This sound wave will also cause the thin iron diaphragm to vibrate. When the thin iron diaphragm moves, it will compress the carbon particles inside, reducing the gaps between the carbon particles, which will cause the structure to change and the carbon particles will contact the wires below.]

[Before that, let's review some knowledge about electricity. U=IR]

[Once the structure of the carbon particles changes, the resistance of the wire on the microphone side will change accordingly. The carbon particles here are equivalent to a sliding resistor. When the resistance of the carbon particle microphone changes, if the voltage remains unchanged, the current of the entire circuit will be forced to change.]

[In this way, we convert the sound signal into an electrical signal, that is, the change in the strength of the electric current. As long as the electrical signal is restored to a sound signal in the receiver, the sound can be transmitted over a long distance. Isn't this the thousand-mile sound transmission mentioned in martial arts novels? This is much more interesting than a telegraph.]

[If you travel back to ancient times and happen to invent electricity, you can also invent a telephone. This kind of cross-era product will definitely be a dimensionality reduction blow to the ancient times. It's not too much to confer the title of Duke on him, right? ]

In front of Fengtian Hall.

The playful look of the crowd disappeared in an instant.

"It's a telephone that can transmit sound over a thousand miles!" Even Liu Ji and others couldn't help but get excited. Even though they had already witnessed the magical manufacturing of the telegraph machine and the wired telegraph system was already under construction.

But... nothing could be more shocking than the art of transmitting sound over a thousand miles. This is the magical skill they have been longing for for a long time. Who wouldn't want to be able to transmit sound over a thousand miles and talk to their parents at home in Jinling on a daily basis?

"There is also some knowledge related to electricity, U=IR, U is voltage, I is current, and R is resistance. That is to say, after the power is turned on, it must contain these three." Everyone in the science department also hurriedly got busy. Du Ping listened to Tianmu's simple introduction to some basic content, and for a moment he felt a little itchy in his head.
"This telephone still plays with electricity." Zhu Yuanzhang was also a little surprised. The research on the characteristics of electricity in later generations has simply reached the level of "carving patterns on rice grains". Just the method of changing the current by changing the resistance is enough to make everyone drop their jaws.

Zhu Yuanzhang was thinking in his mind that the value of the telegraph alone was inestimable, not to mention its upgraded version - the telephone, which was simply a priceless magic trick. If he could really help the Ming Dynasty develop the telephone, what would being conferred the title of duke be worth?
"This structure is so ingenious!" Zhu Biao also cheered, "Then, for the earpiece, can't the principle of electromagnetism be used to allow the thin iron diaphragm to be pulled by the changing magnetic field, and then vibrate up and down to produce different sounds?" Zhu Yuanzhang, Hu Weiyong, Liu Ji, and even everyone in the Science Department knew that the Crown Prince was very talented in physics and had profound attainments. They didn't expect that his mind was also very fast in application. After a little thought, he felt that this method was feasible.

"Excellent! Your Highness the Crown Prince is brilliant!"

"It really works!" The people in the Science Department are no longer the rookies who knew nothing when it was first established. After more than half a year of dedicated research, although they are still unable to conduct independent research, they have become familiar with some electromagnetic phenomena.

There are also a group of people in the Science Department, such as Du Ping, who admire His Royal Highness the Crown Prince. His Royal Highness the Crown Prince is not only approachable and humble, but also has profound attainments in physics. Every time they discuss a problem, they can always come up with some useful suggestions, so everyone respects him very much.

So no matter it was respect or flattery, there was endless praise. Zhu Yuanzhang watched with joy and did not stop it. Seeing that Biaoer had some talent in this area, he was also very proud.

In addition, he also tried his best to find opportunities to establish Zhu Biao's prestige in order to deter some villains in the dark.

As for the fourth one?

Haha, Zhu Yuanzhang sneered, look at what kind of ugly things they are.

[Let's take a look at what this receiver looks like. It actually uses the principle of electromagnetism. The wire is wrapped around an iron rod, and when current passes through it, a magnetic field is generated, which is what we often call an electromagnet.]

[Once there is current passing through the wire, it will become magnetic. Because the current changes from time to time, the magnetism of the electromagnet will also be strong and weak.]

[Because the electromagnet is magnetic, it will attract the thin iron diaphragm next to it. The stronger the magnetism of the electromagnet, the greater the attraction of the thin iron diaphragm. The weaker the magnetism, the smaller the attraction of the thin iron diaphragm.]

[When the sound changes, the resistance changes, which in turn causes the current to change, so the magnetism of the electromagnet at the receiver end also changes, causing the thin iron diaphragm to vibrate here, and once it vibrates, it will make a sound.]

[So the original current signal, after passing through our earpiece, is converted into a sound signal and output to it]

【Let’s talk about our current wireless communication. Do you think there is any problem in promoting this model? 】

[Actually, there is a problem. This is a very simple one-to-one connection. If there are two customers in each place, then in order to ensure that they can communicate with each other, does it mean that each household must pull out a wire to the other three households? ]

[With the explosive increase in the number of users, the telephone company would have to deal with a lot of trouble just laying wires. Moreover, this approach is stupid and inefficient. The solution is also very simple, that is, switches.]

"Sure enough!" Everyone made a 'yeah' gesture, which seemed to make them happier than their own predictions.

"This looks so simple. I feel like I can rub it out with my hands!" Everyone was talking and laughing in a relaxed manner. It is foreseeable that this method of transmitting sound over long distances will soon become popular.

The last time everyone knew about this "telephone" was more than eight months ago. Fast forward. I never thought that I could make one by hand.

"This is the power of knowledge!" Song Lian couldn't help but sigh. No wonder the Four Books and Five Classics were abandoned by later generations. In comparison, the words of the sages could neither make the crops in the fields grow more food, nor could they resist the strong ships and cannons of the various countries in a hundred years of humiliation. In the end, it could not even comfort those ordinary people living in troubled times.

The more he understood Tianmu, the more desperate he felt. Now, he also believed that future generations were right. After all, this was the smooth road that had been paved out through thousands of years of stumbling.

It is also the only smooth road.

In contrast, it is obvious what the people's choice is. Everyone is cheering for the various inventions of new knowledge because they will become a part of their lives in the near future, and everyone's life will be visibly better.

For a moment, his waist seemed to be more bent.
"What is the structure of this switch?" Sun Chuanshi from the Science Department scratched his head. The question raised at the end of the video was one they had never considered, not even when they were laying telegraph wires.

"This is a great way to break the chapter!"

"Hiss, I finally understand why people in later generations hate those who break up the chapters so much!" Many people said madly. This has almost become a necessary skill for these bloggers. After all, if they break up the chapters, they can make another video.

"You still have to support yourself!" Zhu Yuanzhang laughed happily, but he looked at Zhu Biao, as if he hoped that he could solve this problem.

"Maybe we can reuse some of the wires? For example, everyone can connect to the public wires?" Liu Ji didn't pay attention to the emperor's expression, and took over the conversation. As he spoke, he quickly drew two households at both ends of the paper.

There is only one wire in the middle, and both the left and right sides are connected to this wire. This is the most convenient model.

Everyone came over and looked at the model, deep in thought.

"If there are two families A and B on the left, and C and D on the right, how can A communicate with C?" Sun Chuanshi said expressionlessly. This is a problem that everyone can think of, and it is also a problem that must be faced.

"According to this model, everyone on the same line will be able to hear their conversation, which is too unsafe." Du Ping also mentioned.

Liu Ji was silent, then he drew a circle between A and B and the public wires, and between C and D and the public wires, "This part is probably the switch. Normally, the wires between A and B, C and D and the switch are disconnected. When a call is needed, connect to the switch first, and then control the switch to connect two of them for the call."

Everyone was silent and thought for a while. This structure was logically sound and it even solved the problem of conversations being eavesdropped.

Zhu Biao frowned and said, "What if we want to have a simultaneous call? For example, A and C, B and D? Or even more users joining in."

Not only Liu Ji, but everyone else's expressions changed again and again. Everyone who was just talking simply fell silent again. This simply seemed endless.

"These discussions are all meaningful. Let's put away the structural diagram first and see what the comments section says!" Zhu Yuanzhang said. When the ministers were deadlocked over these things, he would come out to calm everyone's emotions.

Many people looked at the comment section helplessly, hoping to find inspiration from there.

"How does the tightness of carbon particles affect the size of resistance? [Covering face]"

"Carbon is conductive, and air is not. If the carbon is squeezed together tightly, the contact area between them will be large, and the resistance will be small. If the carbon is very loose, there will be mostly air between them, and the contact area will be small, so the resistance will be large."

(End of this chapter)