This is a classic barometric test.
The most technical device is probably this glass. Xia Fan commissioned Luo Qingqing to specially bake it from dragon scales. Although it appears a deep green color due to impurities in the sea sand, it does not hinder its excellent light transmittance.
Place four candles into a basin filled with water, then light the candles and invert the glass.
In full view of the public, the candle quickly ran out of oxygen and went out.
Then the water surface inside the cup rises rapidly at a speed visible to the naked eye.
In less than a few breaths, the water pouring into the cup crossed the basin outside and almost reached one-third of the wall of the cup. From a distance, it looked like a new "hill" had risen in the basin.
Before that, the inner and outer water surfaces were still at the same level!
"How does this water... move?"
"It feels like I'm being sucked up by something!"
The children's interest was immediately aroused.
"Everyone may wish to think about why this phenomenon occurs." Xia Fan looked at everyone again - in fact, he had arranged for the Privy Council's envoys to be among the audience, just to prevent the silence caused by no one answering.
But this time someone told the answer in advance.
"Could it be that what you are trying to say is that because the gas inside the bottle is exhausted, the gas outside squeezes the water surface and pushes the water into the bottle?"
"Correct." Xia Fan looked around curiously, and what he saw was a little girl. Judging from her location, she should be a guest invited by Fang Xiandao.
To be honest, although this experiment is classic, it is not as shocking as the hemisphere experiment. You need to go around in a circle to understand the principle. The other party seems to be young, but she can think of this quickly. Could it be that she is also a living dead
"Then can I ask a few more questions?" Qianyan stood up from her chair, which suddenly made her shorter. "People in front of me, please give way."
Probably because they had never seen such a charming little girl, everyone involuntarily opened a passage.
"Lord Qianyan..." Fang Yanni's face turned pale.
"Don't worry." Fang Xiandao comforted him, "The Xia Fan I know is not the kind of person who bullies others."
Xia Fan on the other hand nodded with interest, "Of course, you say so."
"Since there is pressure in the air, why don't we feel tired or feel crushed even when we relax?"
"It's the same as this bottle, because there is air in our body, and the inside and outside just cancel each other out. If the air is taken out, the weight will be enough to crush a person."
"What exactly is air? Does it have an entity? Can it be touched directly?" Qian Yan asked.
If it were the theory of reality and reality in the past, they would definitely avoid answering this kind of question directly and instead talk about some mysterious and profound truths.
"Of course it does." However, Xia Fan did not forcefully change the topic, "You can think of gas as a thinner form of water, so when the temperature is low enough, it will freeze like water and become visible to the naked eye. 'Ice Pimples' - I think at that time maybe you can see more intuitively that you are touching an entity."
"Can the air be frozen?" Qianyan couldn't help but be stunned. She never expected that she would get such an answer, "How low is the temperature?"
"It's much lower than the freezing point. This temperature may be difficult to achieve at present, but as long as you work hard in this direction, I think you should be able to see it one day - doesn't frost condensation condense the water vapor floating in the air into ice? ?”
Qian Yan looked thoughtful, and after a long time she raised her head, "These are just your speculations, right?"
Xia Fan did not deny it.
She hesitated, "That is to say...it is doubtful whether this conclusion is correct."
"I know it is indeed unimaginable. This is also one of the great joys of studying things: deducing the principles behind things from the details that can be seen everywhere, and applying them to a wider range of fields, even if it is counterintuitive." Xia Fan turned to the enthusiastic Students, "Quiet, everyone! I have also prepared another experiment, which will let you see that air not only fills the surroundings like water, but people can also do incredible things with it!"
This experiment is no longer limited to the small space of a glass bottle, but takes the world as the stage.
Of course, a simple interesting experiment on air pressure would not satisfy Xia Fan. He strived to make this open class the first shot in the school's reputation, so he did not hold anything back.
And to show the charm of air, what can be more impressive than a representative machine that integrates various aerodynamic studies and represents mankind's conquest of the sky
At his signal, two guards carried a biplane into the hall.
Although its size can only be said to be at the level of a model, it instantly attracted everyone's attention with its unique shape. At first glance, it looked a bit like a kite, but everyone soon discovered that it was much thicker than a kite, and its size was close to half a person's height. , the two wings are more than an arm's length. The thing didn't move at all when it was placed on the ground, and its weight was evident.
The next step is to use smooth wooden boards to build a runway about a hundred meters long.
Xia Fan originally thought that the electric motor, the key to the biplane model, would be difficult to polish by hand, but Mo Yun gave him a surprise. The slender iron rod used as the rotor was shaped by precise hands bit by bit. In contrast, the copper wires and magnets surrounding the rotor are just the experience accumulated in the four-wheel drive era and do not require much work.
Providing energy for the engine are two sets of indigenous capacitors. They are made of layers of gold foil and varnished paper stacked on top of each other. In order to prevent the insulation layer from being broken down, the surface of these varnished papers is also coated with sealing wax to ensure that electric charges do not fly up and down.
What charges the capacitor is the first level of streamer technique. Even after using thousands of earthquake techniques, Xia Fan burned several trial products before he mastered the strength of charging the local capacitor.
Of course, he can also hold wires to directly provide energy for the model machine, but this "wired remote control" is easily reminiscent of a kite, and it inevitably lacks the feeling of freely chasing the wind.
"What is this?" Qian Yan couldn't help but ask.
"A vehicle that allows people to fly in the air, but it is just a model now."
"Soaring... in the air? You mean, it can fly?"
This sentence is also a question for everyone. After all, the model machine looks too heavy and clumsy.
"Because air flows like water, as long as it is used properly, it can also hold up things hundreds of times heavier than itself, just like a ship weighing thousands of pounds can float on the sea." Xia Fan replied with a smile. Seeing that everything was ready, he flipped the switch that connected the circuit.
The blades at the nose of the aircraft rotated rapidly and made a loud buzzing sound!
The motor does not require a boost, it will run at maximum twist as long as power is supplied.
Driven by the propeller, the biplane began to move forward slowly, getting faster and faster. Until the pressure difference between the upper and lower wings exceeded the weight of the aircraft, it seemed to be lifted upwards by a pair of invisible hands. In the unbelievable eyes of more than two hundred people, it suddenly left the ground and roared into the sky!
The scene was silent for a moment.
Xia Fan knew that the two sets of capacitors could only power it for a few dozen seconds, after which it would fall to the ground under the pull of gravity. But just these few dozen seconds are enough to leave an indelible impression in people's hearts.