More than 1,000 years ago, Mozi conducted experiments on the imaging of small holes. He made it clear that light travels in a straight line, and that the image formed by an object passing through a small hole is an inverted image. This is because when the light passes through the object and then passes through the hole, due to the straight line propagation of the light, the upper part of the object is imaged below, and the lower part of the object is imaged above, so the image is inverted. He also discussed the relationship between the size of the image and the oblique positive of the object and the distance of the light source, pointing out that if the object is oblique or the light source is far away, the shadow is long and thin, and if the object is positive or the light source is close, the shadow is short and thick, and if it is reflected light, the shadow is formed between the object and the light source.

In addition, Mozi has conducted a fairly systematic study of plane mirrors, concave mirrors, convex mirrors, etc., and has derived a series of basic principles of geometric optics. He pointed out that the plane mirror forms an image of the same size, symmetrical from near and far, but reversed from left to right. If two or more flat mirrors are illuminated in the opposite direction, repeated reflections will occur, resulting in an infinite number of images. The imaging of the concave mirror is to form a positive image within the "middle", which is large from the far from the "middle", small from the "middle", and as large as the object at the "middle"; Outside the "middle", it is an inverted image, near the "middle" is like a large, far "middle" is like a small. Convex mirrors only form a positive image, with large near mirrors and small far mirrors.

Although Mozi has not yet been able to distinguish the difference between the center of the sphere and the focal point, and confuses the center of the sphere with the focal point, his conclusion is basically consistent with the imaging principle of modern spherical mirror.

In the history of optics, Mozi was the first scientist to conduct systematic research on geometric optics. It would not be an exaggeration to say that Mozi laid the foundation of geometric optics, at least in China. As Joseph Needham said in the physics volume of The History of Science and Technology in China, Mozi's research on optics was "earlier than what we know from Greece" and "incomparable with India".

At this moment, when Mo Huai heard Li Zexuan's answer, he was not as surprised as the previous two times, but continued to ask: "Why is there an image of an upside-down object~?" If Li Xiannan doesn't want to explain, then you can take this question as the fourth question of the old man~! ”

Li Zexuan waved his hand and smiled: "No need, since the giant wants to hear why, then the kid will explain it well, and it won't be counted as one of the five questions~!" ”

He is now more and more interested in Mohuai, so his self-proclaimed self-proclaimed has also changed from the beginning of the Lord to a brat, although he is confident to win this gamble, but to give others a little face, so that others lose the heart, so that Mohuai will teach students in the future will also teach willingly, dedicated~! This is not called cowardice, but the demeanor of the winner~!

Li Gang frowned slightly, and secretly said that Li Zexuan was a little overbearing, but Mo Huai was also his old friend, so he couldn't jump out to stop it at this time, right~?

Li Zexuan asked Xiao Anren to bring pen and ink, and then motioned for Mo Huai to come over, and he slowly said while drawing the optical path diagram of the small hole imaging system:

"Giant, please take a look~! This is a candle, and the flame of the candle is seen as a combination of many small glowing dots, each of which emits light in all directions. There will always be a small beam of light that passes straight through the hole, creating a small spot behind the hole. Therefore, each luminous point on the candle flame will form a corresponding light spot on the white paper, and all the light spots on the white paper will form a candle flame image ............"

With Li Zexuan's narration, Mo Huai suddenly realized, and now he finally knows both what it is and why it is, but at the same time, he looked at Li Zexuan with a very strange eye, as if he was looking, monster~!

At this moment, Mo Huai had a very great curiosity about Li Zexuan's origin, first of all, being able to become a martial arts master at the age of fourteen or fifteen years old is already a unique exception in the world, however, Li Zexuan still has such deep attainments in these very remote fields, both civil and military cultivation, and every aspect can achieve an existence that is difficult for ordinary people to achieve, Mo Huai can't imagine what kind of family, what kind of gentleman, can teach such a demon~?

"How~? I don't know if what the kid said is right~? ”

Li Zexuan's scalp was numb from Mo Huai's eyes, so he couldn't help but say.

Mo Huai nodded silently and did not say a word.

Li Zexuan said: "Then please ask the giant to continue to ask the fourth question~!" ”

Hearing this, Mo Huai took his eyes off Li Zexuan, sighed heavily, and then bent down to Li Zexuan, arching his hand and saying, "No need to come out, the old man admits defeat~!" From now on, the old man's old bones will be driven by the man of Li County, without asking for compensation, and working hard and complaining~! ”

"Uncle~! Cannot~! ”

"Uncle~! Don't~! ”

Mo Zhong and Mo Yun were shocked when they saw this, and they all shouted.

As a giant of the Mo family, Mo Huai's knowledge and martial arts are all examples that they have admired and chased since childhood, and now, the god-like man in their eyes actually bowed his head to a fourteen or fifteen-year-old young man, how can they bear it~? Although Li Zexuan is indeed very powerful, Mo Zhong and Mo Yun still can't accept this reality.

"Shut up~! As a giant of the Mo family, how can the old man be untrustworthy~? Mo Zhong, Mo Yun, the two of you will step back first, and the old man will elect the next Mo family giant in the future~! ”

When Mo Huai heard this, he hurriedly reprimanded loudly, and then he bowed his hand to Li Zexuan: "Lord Li, please give the old man a month of grace, and when the old man returns to the Mo family's station, after picking out the next giant, he will go to Chang'an to teach students wholeheartedly~!" ”

Now Mo Huai's gentle request looks, how can he still have the kind of vigor at the beginning~? It's a little more sad at the end of the hero~!

Li Gang looked at it, and his heart was extremely unbearable, after all, this was his old friend who had been friends for many years, so he said loudly: "Brother Mo, you don't have to be like this~!" Your position as a giant does not conflict with the identity of a teacher in Yanhuang Academy~! Xiao Xuan is not the kind of person who is not close to people, he will not restrict your freedom~! You can manage the affairs of the Mo family while teaching in Yanhuang Academy~! Besides, the Mo family has declined to this day, how many affairs still need you to manage~? ”

The corners of Li Zexuan's mouth hooked an arc, and secretly said that his opportunity had come, and he hurriedly interjected: "Mr. Li is right, you go to Yanhuang Academy to teach, the kid will definitely not restrict your freedom, and the salary you should have, the kid will definitely not lose a penny of your money~!" In addition, you can move the Mo family's residence to Chang'an~!

At that time, all the ink masters of the Mo family will be settled by the kid, and if there are ink masters like you who are proficient in mechanics, optics or mechanical equipment, the kid is also willing to hire them to Yanhuang Academy~! As for the treatment and salary of Mr. Academy, you must also know that the kid will not repeat it, how do you think about it~? ”

…………………………

(End of chapter)