Chapter 267 Blackbody Radiation Experiment

Before coming to France, Zhang Xingjiu had already thought about his main direction. It was impossible to engage in invention research. With China's current industrial capacity, no matter what he researched, the only ones who would benefit would be the developed countries in Europe and America.

If the gap between China and developed countries in Europe and America widens due to his own faults, Zhang Xingjiu will be doomed to die.

For example, he does have the technology to synthesize ammonia in his mind. If he dares to use it, the war capabilities of European and American countries will suddenly increase. Once they have fought enough, it is easy to imagine what they will do next. Therefore, this thing must not be used.

Theoretical physics is much better. The development of theories will certainly promote the development of applications, but this often takes time, and sometimes a very long time. It only takes time to seize the opportunity and be slightly ahead of theoretical physicists in Europe and the United States for a few years, and it will not cause too much interference to history.

The biggest problems in the field of theoretical physics right now are these two dark clouds. It is really appropriate to use this to make a name for himself, because even without Zhang Xingjiu, European and American physicists would have made a breakthrough soon. He just brought the time forward a little bit.

"I read in a journal that a researcher at the German Imperial Institute of Physics and Technology, Wien, recently derived a semi-empirical blackbody radiation formula from a thermodynamic perspective, called the 'Wien approximation'. It has just not been verified experimentally. We can design an experimental plan to test this formula."

Any object has the property of continuously radiating, absorbing and reflecting electromagnetic waves. The radiated electromagnetic waves are different in different bands, that is, they have a certain spectral distribution.

This spectral distribution is related to the properties of the object itself and its temperature, so it is called thermal radiation. In order to study the laws of thermal radiation that are independent of the specific physical properties of the substance, physicists have defined an ideal object - the black body, as a standard object for thermal radiation research.

In real life, coal is the substance closest to a "black body". When heated, it first emits red light (longer wavelength, lower frequency). As the temperature rises, the color of the light changes from red to yellow, and finally to blue (shorter wavelength, higher frequency).

Later, in a broad sense, any phenomenon of heated matter emitting electromagnetic waves can be called "blackbody radiation". Physicists explore the relationship between the energy, temperature and wavelength of "blackbody radiation". The formula that Wien came up with not long ago tried to use mathematical methods to describe this relationship.

It’s just that his formula is not accurate, and the loopholes in the formula can be found through experiments. German physicists proved this a few months later. Zhang Xingjiu has just brought the time forward slightly.

"How do you plan to do the experiment?" Pierre asked with interest. He has been in charge of the laboratory for more than ten years and is far more interested in experiments than boring theories.

"Try to heat the black body and measure data indicators at different wavelengths. Wien believed that when the wavelength tends to infinity, the energy density is independent of temperature. We can test this hypothesis through data." Zhang Xingjiu took out the experimental plan of German physicists Lummel and Prinsheim.

Lang Zhiwan thought silently for a while, then suddenly opened his eyes, "In theory, this method should be feasible, but the measurement range must be larger, because Wayne must have conducted experiments, and the data must conform to his formula, otherwise he would not have produced it."

"If we conduct this experiment, we need heating equipment, a suitable black body, and most importantly, the thermal radiation meter invented by American scholar Langley. This is the best measuring tool. Combined with the Rowland concave grating, we can get a very accurate thermal radiation energy distribution curve." Zhang Xingjiu looked at Pierre.

"The school's laboratories have these devices, but ordinary students are not allowed to use them. You must come up with a complete experimental plan to convince Professor Lipman. I can help persuade him, but I can't guarantee success. Professor Lipman is very stubborn in academics. If your plan is not good enough, he will not approve it," said Pierre.

"Can you give me a few approved experimental plans so that I can learn their writing style?" Zhang Xingjiu was not in a hurry to start writing the plan immediately. The format of the plan today must be very different from that of later generations. If the difference is too big, Professor Lippmann might not be used to it and would reject it without even reading the content.

"No problem, I'll give it to you after class tomorrow." These are all small matters. Pierre himself is the head of the laboratory, and he has many similar plans.

"I am also very interested in this topic. Please include me when you write the proposal." Lang Zhiwan quickly interrupted. He didn't want to steal Zhang Xingjiu's idea, but he was really interested in this issue.

Zhang Xingjiu was also happy to have someone to help him, and he had a good impression of Lang Zhiwan, who would later become a member of the French Communist Party and had expressed support for China on many public occasions. He was a genuine international friend, and he still hoped to have a good relationship with such a person.

So from that day on, Lang Zhiwan would run to Zhang Xingjiu as soon as he got off get out of class every day to write the experimental plan with him. Fortunately, the École Normale Supérieure in Paris and the Sorbonne University were not far away, so it was not too troublesome.

At this time, Zhang Xingjiu's guest room came in handy. Sometimes when the two of them were busy too late, Lang Zhiwan would go directly to the guest room to rest without having to run back and forth.

A week later, Zhang Xingjiu handed the written plan to Pierre, who checked it first and pointed out a few minor problems in writing habits. After Zhang Xingjiu revised it, he gave it directly to Lippmann.

Zhang Xingjiu performed well in class. He listened carefully, actively answered the teacher's questions, and completed his homework quickly and well. Whenever he had time, he would hang out in the library. Lippmann often met him when he went to look up information.

What teacher would not like such a student? So Lippmann had a very good impression of Zhang Xingjiu, and now that he saw that his experimental plan was well written, he gave him this opportunity without hesitation.

Pierre prepared the experimental equipment and venue for them, and Lang Zhiwan also slipped into the laboratory. The two began to prepare for the experiment under Pierre's guidance.

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Zhang Xingjiu quickly learned how to operate the thermal radiometer and the Roland concave grating, and he also mastered the steps of heating the black body very accurately. Pierre was very excited when he saw this. "My lab needs an assistant like you who can operate accurately. When Mary and I start a new project, do you want to come and help?"

Oh my god, your new project is not about pitchblende, right? I dare not do that! (End of this chapter)