Daming: Grandpa Emperor, please get up and sit on my throne!

"And this one can create a rainbow." Zhu Yunhuan took out another small piece of glass with a special shape - a prism.

Tianhong, which means rainbow.

The same principle of light refraction is used, which is a common thing in later generations. However, in this era, rainbows have only ever appeared as natural landscapes after rain, and artificial creation of them can be regarded as a fantasy.

Xu Miaojin's eyes brightened even more, with the clarity and curiosity that only a girl of her age could possess. She sighed in disbelief and asked, "Creating a rainbow?"

Zhu Yunhuan didn't say anything.

Instead, he placed a finger-sized prism on the table and adjusted the angle so that the sunlight would come in through the window on the other side, pass through the prism, and project a beautiful little rainbow on the table.

Xu Miaojin opened her mouth wide, her pretty face full of surprise.

"It's really a rainbow! Did you make this too!?" Xu Miaojin asked, looking like a curious baby, lying on the table and observing the prism and rainbow closely from all angles.

Zhu Yunhuan said calmly: "This thing is simple and does not require much effort."

Seeing this "spectacle".

Xu Miaojin temporarily put aside all her previous worries, and stared at the things on the table with her big eyes, unwilling to move away.

Appreciated it for a long time.

She raised her head again and looked at Zhu Yunhuan with a look of scrutiny. Her big eyes turned slightly and she questioned, "Such a mysterious thing, is it really made by human power?"

"Of course." Zhu Yunhuan said indifferently.

"Then you just said... Everything in the world has its own laws and principles of operation. Can you tell me, what are these laws and principles?" Xu Miaojin continued to ask. She considered herself to be well-read, having read the Four Books and Five Classics, ancient classics and history, as well as essays and anecdotes, but she had never heard of such a thing.

Seeing Xu Miaojin's eagerness for knowledge, Zhu Yunhuan's heart moved slightly. "Originally, it was just a sudden impulse to see the aptitude of the Third Young Lady of the Duke of Wei's Mansion, but this little girl took the initiative to ask these questions. Speaking of which, the desire for knowledge and curiosity... these things are often very important in studying mathematics and physics."

I thought about it.

He casually picked up the pen and paper on the table, drew a line on the paper, and asked, "What do you think light is?"

Xu Miaojin blinked and frowned slightly: "Light... the sun has light, candles have light, and night pearls also have light?" She knew this kind of commonplace thing, but to be honest, she had never thought about this question before, and for a moment she didn't understand what Zhu Yunhuan wanted to express.

Zhu Yunhuan said calmly, "For the moment, you can imagine light as an object, something that moves on its own. It starts from the sun, the candle, the night pearl, and reaches your eyes. Only then can you see the so-called light."

Xu Miaojin looked thoughtful.

With a confused look, although he didn't understand or accept it immediately, he nodded and said, "So?"

Zhu Yunhuan nodded with some satisfaction in his heart. For people of this era, these were all new concepts and commonplace things. No one would think about the essence of them, including those officials and prisoners with extremely high cultural levels.

When most people heard about his theories, which they had never encountered before, they either didn't understand or sneered at them and were completely unwilling to think about them carefully.

Probably someone like Xu Miaojin who is a little bit rebellious.

Maybe we can break away from the inherent thinking.

More accepting of these statements and theories.

This is also why Zhu Yunhuan suddenly decided to tell her about these things.

After a pause, Zhu Yunhuan continued to draw the shape of a convex lens on the paper and said, "Let's talk about this magnifying glass first. Light is a moving object, and its trajectory forms a line, just like this." After that, he drew several straight lines with arrows on the left side of the convex lens.