Super Xueba: Start With A Low Control Score!

Chapter 183 Three questions at the finale, easy to get!

The original title is as follows…

“In the classic hydrogen atom model…

The electron moves in a circle around the nucleus, and the centripetal force of the electron comes from the action of the nuclear electric field.

However, the classical electromagnetic theory states that electrons will emit electromagnetic waves when they perform accelerated motion, and their emission power can be expressed as (Larmor’s formula): P=e^2*a^2/6πc^3E0.

Among them, a is the acceleration of electrons, c is the speed of light in vacuum, Eo=1/4πk=8, 854×10^-12Fm^-1, and the absolute value of electronic charge e=1, 602×10^-l9C.

1: Assuming that the relativistic effect is not considered, try to estimate the lifetime τ of the hydrogen atom in the classical model. (The experimentally measured binding energy of hydrogen atoms is E=13, 6eV, and the rest mass of electrons m0=9, 109×10^－31kg).

…

2: Magic City Light Source is the third-generation synchrotron radiation light source built in recent years. Some of its working parameters are as follows…

The electron energy in the ring E=3, 50GeV, the electron beam cluster current strength I=300mA, the circumference L=432m, the number of units (the number of bends equipped with a deflection magnet) N=20, the magnetic induction intensity of the deflection magnet’s magnetic field B=1 , 27T.

Try to calculate the average total radiation power Po of each optical port of the device.

(When electrons approach the speed of light…

Assuming that the momentum does not change, Newton’s second law still holds, but Larmor’s formula is no longer applicable.

The corresponding formula changes to P=(e^2a^2/6πc^3E0)*γ.

Where γ=E/m0c^2, E is the total energy of electrons, and m0c^2 is the rest energy of electrons. ).

…

3: Since the speed of electrons in the reserve ring is close to the speed of light, synchrotron radiation is a light cone along the tangential direction of the electron orbit. The half apex angle of the light cone is. It can be seen that the higher the electron energy, the better the directivity.

Trial calculation: the continuous time △T of radiation produced by a single electron agreed by the above device at a certain point in the radiation direction.

…

…

This is the finale of this competition.

Unlike the 20-point finale question of the Mathematical Olympiad, the finale question of the physics competition occupies 25 points.

The first question is 5 points.

The second question is 10 points.

The third question is 10 points.

However……

As soon as I saw this question.

Fu Xinhan, Lin Qianqian, Lin Yu, Su Mo, Ye Fan and other eight people were all dumbfounded.

This question is very long.

At first glance, I really don’t quite understand it.

However, with the strength of Fu Xinhan and others, it is not difficult to understand the problem, but it feels a lot of pressure to do it.

Are you sure this is the question that should appear in the rematch?

Even the finale question is not too much!

Especially this Lamor formula.

They haven’t even heard of it.

Although it hasn’t started yet.

But it always feels like a cool rhythm.

Second Olympics!

Difficult!

“Damn the teacher!”

“Are you deliberate?”

“Obviously the first and second rounds are just normal competition difficulty, but the third round has increased so much?”

“The same was true in the previous Olympiad competitions. The difficulty of the third round of the finale question is against the sky, almost killing everyone, except for Jiang Nan, who used the so-called S-roll. It is understandable. Why is this competition?”

“Does Wujing also have S rolls?”

“But even if there is an S roll, it’s impossible to use it suddenly?”

“It was Jiang Nan’s kid who used the S volume for Olympiad to provoke Professor Fang Guoping. Why is this competition?”

“Who provokes them?”

“Or are they crazy and deliberately making things difficult?”

“…”

Fu Xinhan, Lin Qianqian, Lin Yu and others have all grabbed countless hairs, but they are still puzzled.

The only thing I can do now.

Just go all out to do the problem.

Can……

The previous question is fortunate to say, although it is difficult, but with their strength, it can still be done.

But in the end, this finale is hard to do.

If you really want to use any sentence to describe it.

That is……

This question is just as good as the previous finale of Mathematical Olympiad.

It is also the kind that has no solution.

Even if they give them more time, they can make at most a fraction of it, and it’s hard to get a score of ninety points, let alone full marks.

Gee!

This slap in the face.

It’s not unpleasant, it’s not heavy.

And the other side.

When Jiang Nan got the paper, he just curled his lips lightly, “Heh, that’s it?”

“It feels a bit more interesting than the first and second rounds, but that’s it! It’s okay to score 100 points easily.”

“but……”

“The system task is 99 points.”

“First finish the paper, then erase 1 point…”

“…”

When the heart was moved, he acted immediately. As soon as he got the paper, Jiang Nan started writing quickly and quickly.

Originally, he was fast, but he won a bachelor’s hand speed*10 in the last lottery, so the speed was even faster.

Even though it was the third round of the competition, he did the last question in less than five minutes.

The original title is as follows…

“In the classic hydrogen atom model…

The electron moves in a circle around the nucleus, and the centripetal force of the electron comes from the action of the nuclear electric field…”

“…”

“…”

“Um?”

“This question is kind of interesting.”

“Although I haven’t seen the Lamor formula, the specific formulas are given, and there are various data…”

“Doesn’t this mean giving points?”

“presumably……”

“Most people do it, right?”

“Fu Xinhan, Lin Qianqian’s group is known as the top eight gods of the four prestigious universities, and they will do it out of ten.”

“But the problem is that the system task has a control score of 99. If they all get full marks, what should they do?”

“I put the words out before, and I want to compete for the first place in four. If I lose this round of exams, don’t I just face myself?”

“System, system!”

“You have to work hard! I still believe in you, I believe that 99 points can get the first place.”

“otherwise……

“I will be ashamed, and you can’t run away either!”

“…”

Jiang Nan comforted himself secretly.

Then began to solve the problem.

“Solution 1: From the equation F=ma, a=v^2/r, F=1/4πε0*e^2/r^2, the total energy of the electron can be derived as U=-e^2/8πε0r0.”

“From the conditions Eh=-13, 6eV, the orbital radius and velocity of the hydrogen atom are deduced to be…

“R0=5, 29×10^-11’m.”

“V0=2, 19×10^6m/s.”

“The initial transmission power is obtained from the Lamor formula…”

“…”

“Substitute data…”

“Get: τ=1, 56×10^-11s.”

“…”

“Solution 2: Regarding high-energy electrons, v=c, E=mc^2, a=v^2/r, F=eBc, F=ma…”

“From the above conditions, the electron deflection radius R=E/ecB(6) can be obtained.”

“…”

“The power of the light outlet is…”

“P0=Putal/N=2, 17×10^4W.

“…”

“Solution 3: Watching at a certain point P in the tangent direction of a certain point on the electron orbit, the viewer can only watch at…”

“…”

“△T=9, 51×10^-20s.”

“…”

sp: The process has been streamlined. I’m afraid of being beaten, as witty as I am!