Chapter 1148 The Children of the Poor Are in Charge of the House at an Early Age

After eating, Su You led Guan'er to his study, and when he saw the push-pull bookshelves in Su You's big study, Guan'er's eyes lit up: "Wow-uncle, you have so many books-"

Su You said with a smile: "Evening is the time of interest, if you like to read, you can take the books on the bookshelf at will, if you like to experiment with your brothers, you can also participate." ”

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

Flat Jar opened a bookshelf, took a ladder and climbed to the top, and took down a thick book of paintings: "Guan'er will show you this, there are many animal paintings and names and habits in it, but it's fun." ”

Guan'er took it: "Thank you, Brother Biancan, what do you see?" ”

Speaking of this flat jar, he was a little unexcited: "Brother wants to make a picture, alas......"

While reading the letters from his friends, Su You picked up his pen and wrote a reply, but he didn't bother to look up: "Alas, alas, I did it myself!" ”

The study was quiet, only the sound of books and letterheads turning and the sound of flat cans and Wang Yanbi discussing and making pictures in a whisper.

After a while, I heard the two boys "also", and then I heard the flat jar say proudly: "I'll just say that Daddy will give a hint!" He said that he carried his own pot, and it turned out that he wanted to make it into the shape of a pot. ”

Su You saw the two boys cheering and said, "Show me the picture." ”

The two boys sent the picture to Su You, and Su You nodded: "There are a few questions, first of all, how can you be sure that the sunlight hits the reflective surface in the form of side-axis rays?" ”

Yes? The two boys were immediately stupid.

Su You smiled: "But it can be considered that you are inspired by the principle of convex lens, and make an assumption. ”

The two boys breathed a sigh of relief.

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

After speaking, he took out a new drawing and made an optical path diagram on the paper: "You see, we assume that the incident light and the optical axis are parallel, and such light is called the paraaxial ray, so the correct optical path diagram is like this......"

"Since this ray is parallel to the optical axis, the radius of the line connecting the center of the sphere and the sphere gives such a diagonal line that cuts through two parallel lines, and according to the principle of geometry, it can be known that the two angles are equal......"

"And because the radius is perpendicular to the tangent of the point of the spherical surface, we can imagine that at this point, the reflection path of the ray is the same as the reflection path of the tangent plane, so that the angle between the reflection line and this radius can be obtained, and this is ......"

"Okay, so then we get an isosceles triangle with a large obtuse angle, and we can see that the focus is actually here, and it's obvious that the distance from the center of the sphere to the focus is an hypotenuse of this isosceles triangle, and the radius of half of the sphere is the bottom half of this triangle, so they must be unequal."

"At this point, we can know that your conclusions are actually wrong."

The two children were immediately depressed.

Su You smiled: "However, science and engineering is the science of using mathematics and physics to guide the operation, in fact, as long as the top angle of this triangle is large enough, and the two bottom angles are small enough, we can approximate that the length of this hypotenuse and one-half of the bottom edge is actually very close, so you define the reflection focus of the concave mirror at one-half of the spherical radius on the optical axis, and it is actually feasible to infer it as an approximation." ”

"Also!" The two children clapped each other's hands: "Daddy, can we make a metal concave mirror that can be used to reflect sunlight to the focal point, and then it can ignite the fire?" ”

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

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

"If you succeed in making a water heater and repair the Spectacle Mirror, you will be spared."

"No!" Bian Jar waved his fist excitedly: "We also have to repair the peephole mirror, and we also have to build the concave mirror!" ”

Soon, the two boys came up with a set of mortar casting mold schemes, first take a large flat iron sheet, cut out an arc, install the central axis and bury it in the wet sand and rotate, you can cut a desired sphere.

Then the tin is poured, and after solidification, the sand is planed to obtain a concave surface.

The concave surface is then coated with a thin layer of tin, and then polished to a bright surface, you can get the desired concave mirror, and the rest is easy to do!

Although many details of this plan still need to be improved, it is quite good to be able to get to this point.

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

After the excavation of many bronze mirrors from a thousand years ago, their surfaces are still as bright as new, and the heavenly master has found that the surface part of the surface contains more than 60% of tin.

In long-term use, a thin layer of tin oxide transparent film is attached to the surface of the copper mirror, which plays a protective role in the copper mirror.

Wang Yanbi said: "I went to ask the emperor's uncle, he definitely didn't care about giving us some tin for experiments!" ”

Su You nodded: "Well, you can also try to atone the merit and make sure that your mother doesn't beat your ass!" ”

Wang Yanbi: "......"

Guan'er obediently flipped through the album on the side, not glancing at this side with her eyes, full of curiosity and envy for the two elder brothers.

The Su family slept late at night, and it was time to go to bed two hours after the lights were lit.

Today, Su You and Shi Wei slept separately, and now Wang Yanbi has to go home every day, and the vacated bed can allow Su You to sleep.

Shi Wei, a colander and Guan'er sleep.

I didn't say anything all night, and when I got up the next day, Guan'er was shocked by the Su family's breakfast again - cakes, breads, pies, buns, all very small, as well as puffed rice milk porridge, small pickles, sesame sauce mixed with vegetables, and diced fruits.

Guan'er is very well-behaved, it is estimated that the two brothers are not very good at taking care of the little girl, I heard the uncle say that the flat can brother went to exercise outside, yesterday it was the flat can brother who put dishes and chopsticks for her, and today she is the one who put the dishes and chopsticks for the flat can brother.

Shi Wei poked Su You lightly, and nodded with him again.

Su You understood in seconds, and nodded to Shi Wei, thinking about how to mention this stubble to Bi Zhongyan in his heart.

And Zhao Ji also needs to get a vaccination, if such a little girl is sent to the palace in ten years, or marries a son, it will be really bad.

Well, I'll go to Zhao Ji today and say.

When the flat jar came back, Guan'er was shocked again, the flat jar brother can really eat it! One cake, one bread, three buns, two bowls of porridge!

I also wrapped a few pies, saying that he and Yanbi were fighting tooth sacrifices between classes!

Bian Jar and Wang Yanbi's courses have surpassed their peers by a lot, whether it is liberal arts or science, so now it is the little sister who opens a small stove for them.

Then send Guan'er over today, Su You wants her to study with peace of mind, and when she finishes class, he will pick her up to see her brother.

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

Su You said: "The uncle who picked us up yesterday is called Uncle Zhang, and his third aunt is a famous music theorist in my Great Song Dynasty, and she is playing the piano." ”

Guan'er showed envious eyes: "I have never seen a piano." ”

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

The two of them, one older and one younger, walked towards the door, and as for the flat jar, they shouted: "Guan'er, I'll wait for you at the academy, you come quickly." "I pedaled my bike and ran away.

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

Guan'er shook her head: "Guan'er likes it very much, but it's already very troublesome Uncle like this." When my brother is well, they will always take Guan'er back. ”

"If you're used to eating delicious food at your uncle's house, and you don't get used to it when you go home, it's not good."

Su You asked in surprise, "Guan'er, how old are you?" ”

Guan'er said: "I am eight years old this year. ”

Su You was a little speechless, he was able to restrain his desires in the face of a rich breakfast and plan for the days to come, is this also a poor man's child in charge?