Chapter 1,148: Children of poor people become rich early

After dinner, Su You led Guan'er to his study. As soon as he saw the push-pull bookshelf in Su You's big study, Guan'er's eyes lit up: "Wow - uncle, you have so many books at home.

——”

Su You smiled and said: "Evening is your hobby time. If you like to read, you can take a look at the books on the shelf. If you like to do experiments with your brothers, you can also participate."

Guan'er was very curious about the dazzling array of mineral specimens, animal and plant specimens, mechanical structures, etc. in Su You's study room. He didn't know where to start for a while.

Flat Pot opened a bookshelf, climbed up with a ladder, and took out a thick book of paintings: "Guan'er, let me show you this. There are many paintings, names, and habits of animals. It's really fun."

Guan'er took it and said, "Thank you, brother Bian Guan. What are you looking at?"

When talking about this flat jar, I became a little unexcited: "Brother wants to draw a picture, alas..."

While Su You was reading the letters from his friends and writing replies, he didn't even bother to raise his head: "What the hell, it's your own fault!"

The study became quiet, with only the sound of books and papers being turned and the sound of Bian Guan and Wang Yanbi discussing and composing pictures in a low voice.

After a while, I heard the two boys say "yeah", and then I heard Bian Gu say proudly: "I guess daddy will give you a hint! He said that he carried the pot by himself, so it turned out that he wanted to make it into the shape of a pot.

"

Seeing the two boys cheering, Su You said, "Bring the picture to me."

The two boys sent the picture to Su You, who nodded: "I have a few questions. First, how can you be sure that the sunlight hits the reflective surface in the form of paraxial rays?"

Huh? The two boys were immediately stunned.

Su You smiled and said: "But it can be thought that you are making an assumption inspired by the principle of convex lenses."

The two boys breathed a sigh of relief.

"But your inference that the focus is at the center of the sphere and one-half of the spherical surface on the optical axis is wrong."

After speaking, he took out a new drawing and made a light path diagram on the paper: "Look, we assume that the incident light and the optical axis are parallel. Such light is called paraxial ray. Then the correct light path diagram is

so……"

"Because this ray is parallel to the optical axis, through the radius of the line connecting the center of the sphere and the surface of the sphere, we get such an oblique line that cuts through the two parallel lines. According to geometric principles, we can know that these two angles are equal..."

"And because the radius is perpendicular to the tangent line at this point passing through the sphere, we can imagine that at this point, the reflection path of the light is the same as the reflection path of the tangent plane, so we can get the angle between the reflection line and this radius, like this...

…”

"Okay, now we have an isosceles triangle with a large obtuse angle. At this time we can see that the focus is actually here. It is obvious that the distance from the center of the sphere to the focus is an oblique slope of this isosceles triangle.

side, and one-half the radius of the sphere is one-half the base of the triangle, so they must be unequal."

"After calculating this, we can know that your conclusion is actually wrong."

The two children were immediately dejected.

Su You smiled: "However, science and engineering are sciences that use mathematics to guide operations. In fact, as long as the vertex angle of this triangle is large enough and the two base angles are small enough, we can approximately think that the hypotenuse and half

The lengths of the bases of one are actually very close, so you define the reflection focus of the concave mirror at half the radius of the spherical surface on the optical axis, and it is actually feasible to use this as an approximate inference."

"Yes!" The two children high-fived each other: "Dad, can we make a metal concave mirror to reflect the sunlight to the focus and ignite the fire?"

Su You smiled and said: "Yes, but to turn this theory into reality, we need to design a feasible plan, which is not that easy."

"If you can design a feasible plan, you can go to Uncle Shi and make a concave mirror water heater to boil the rootless water you receive and see if you can become an immortal after drinking it."

"If we successfully manufacture a water heater and repair the sky mirror, I will spare you the trouble of repairing the sky mirror."

"No!" Bian Guan waved his fist excitedly: "We also need to repair the sky-gazing mirror and build a concave mirror!"

Soon, the two boys devised a plan for mortar casting. First, they took a large piece of flat iron sheet, cut out an arc, installed a central axis, buried it in the wet sand and rotated it, and then they could cut out the desired shape.

Spherical surface.

Then pour tin, and after solidification, remove the sand to obtain a concave surface.

Coat the concave surface with a thin layer of tin, and then polish it until it is bright. You can get the concave mirror you want, and the rest is easy!

Although many details of this plan still need to be perfected, it is already quite good to have reached this point.

This is the principle of making so-called "mercury Qin" bronze mirrors in ancient times!

After many bronze mirrors dating back thousands of years were unearthed, their surfaces were still as bright as new. Through chemical composition analysis, Tianshi found that their surfaces contained more than 60% tin.

During long-term use, a thin layer of transparent tin oxide film is attached to the surface of the bronze mirror, which protects the bronze mirror. The antique shop has a professional term for this kind of bronze mirror, which is called "mercury Qin".

Wang Yanbi said: "I will ask the emperor's uncle, he will definitely not care about giving us some tin for experiments!"

Su You nodded: "Well, you can also try to offset the merits and make sure your mother doesn't spank you!"

Wang Yanbi: "..."

Guan'er was obediently flipping through the picture album, not just glancing over here, full of curiosity and envy for the two brothers.

The Su family goes to bed late at night, lighting the lamp for two hours before going to bed.

Today Su You and Shi Wei sleep separately. Now that Wang Yanbi has to go home every day, Su You can sleep on the free bed.

Shi Wei, Colander and Guan'er sleep.

There was nothing to say all night. When he got up the next day, Guan'er was surprised again by the Su family's breakfast - cakes, breads, pies, steamed buns, all very small, as well as puffed rice milk porridge, small pickles, and vegetables mixed with sesame sauce.

There are also diced fruits.

Guan'er is very well-behaved, probably because her two older brothers are not very good at taking care of little girls. I heard from the uncle that brother Bian Guan went out to exercise. Yesterday, brother Bian Guan set the dishes for her, and today it was she who set the dishes for brother Bian Guan.

Set the dishes and chopsticks.

Shi Wei poked Su You lightly and nodded to him.

Su You understood immediately and nodded to Shi Wei, thinking about how to raise this issue with Bi Zhongyan.

Zhao Xu also needs to be vaccinated. If a little girl like this is sent to the palace ten years later, or marries a pedant, it will be really bad.

Well, I went to find Zhao Xu today and talk about it.

When Bian Guan came back, Guan'er was shocked again. Brother Bian Guan was really good at eating! One meal included a cake, a piece of bread, three buns, and two bowls of porridge!

I also made some pies and said I was having a toothpaste with Yanbi during recess!

Bian Guan and Wang Yanbi's courses are already much better than those of their peers, whether in liberal arts or science, so now it is their younger sister who teaches them.

Then he would send Guan'er there today. Su You asked her to study with peace of mind and would pick her up to see her brother after he finished class.

When he came to the outer courtyard, Guan'er heard a beautiful sound of musical instruments and asked, "Uncle, what kind of music is that? It's so nice."

Su You said: "The uncle who welcomed us in yesterday is called Sanshu Zhang. His third aunt is a famous music theory expert in the Song Dynasty. She is playing the piano."

Guan'er showed envy in her eyes: "I have never seen a piano."

Su You smiled and said: "If you are interested, you can use it as a hobby class in the evening, just like the two brothers playing with physical and mechanical models at night."

The older one and the younger one walked towards the door. As for Bian Gu, he shouted: "Guan'er, I'll wait for you at the college. Come quickly." He pedaled his bicycle and ran away.

Su You suddenly thought of something: "Guan'er, you don't like today's breakfast? What do you like to eat? I'll ask the kitchen to change it for you."

Guan'er shook his head: "Guan'er likes it very much, but it's already troublesome for uncle. When my brother gets better, they will always take Guan'er back."

"If you are used to eating delicious food at uncle's house and are not used to it when you go home, that will not be good."

Su You asked in surprise: "How old are you, Guan'er?"

Guan'er said: "I am eight years old this year."
Chapter completed!