"Before, I didn't have a choice. Now, I just want to be a quiet student. Shen Qi poured out from the bottom of his heart.

"You just pretend to be quiet, Shen Qi boss!" The boy wiped away his tears and stopped crying, and the boy should be self-reliant, he asked: "By the way, how much did you score in this theory test?"

“280。 ”

"I ...... I am seriously unwell...... I'm going to report you, Shen Qi!" the boy slammed his fist on the big tree next to him.

"Please don't do that, my friend. Shen Qi stood up, turned around and prepared to leave.

"Wait a minute, big guy!" the boy grabbed Shen Qi's arm and said very eagerly: "Do you have a pen with you?" ”

Shen Qi had a pen in his pocket, which Mu Rong gave him when he filled out the form just now, but Mu Rong forgot to take it.

"Here, I've got you. Shen Qi took out the water-based pen and handed it to the boy.

"Thank you, big guy!" The boy took Shen Qi's pen and swept away the decline: "The magic pen is in hand, and the exam is worry-free!" Shen Qi boss, I wish you steady progress on the road of pretending to be forced, and be promoted to the new generation of Yan Da as soon as possible!"

……

The next day, the CPhO experiment was carried out.

80 points for experimental questions and 280 points for theory questions.

Experiment + Theory is the overall result of this national referendum.

Shen Qi got a perfect score of 280 in the theory exam the day before yesterday, and as long as he does not make low-level mistakes in today's experiment, his total score will enter a higher range.

Why is the player from Suzhou and Hangzhou No. 2 Middle School who met yesterday crying, because his theoretical score is only 172 points, even if he gets a full score of 80 in the experiment, his total score cannot be higher than Shen Qi's theoretical score.

Of course, the theory test is the highlight of the national final, but the experimental questions cannot be relaxed.

All the contestants are divided into two groups, one in the morning and one in the afternoon, and the experimental questions in the morning and afternoon are all electrical experiments, with different questions but similar difficulty.

Shen Qi drew the lottery to do experimental questions in the afternoon.

The experimental instruments and utensils issued by the invigilator are:

1 DC regulated power supply, 2 digital multimeters, 2 potentiometers, 1 standard resistance box, 1 DC galvanometer, 1 constant temperature water bath, 1 diode to be tested, 1 programmable calculator, and several wires.

The experimental requirements are:

An experiment is designed according to a given experimental instrument to accurately measure the forward volt-ampere characteristics of the diode at t=27°C. The current varies from 0.5 to 1000 μA, and no less than 20 sets of data are required to be measured.

In addition, draw a circuit diagram, explain the experimental principle, write out the experimental procedure, and design a table to record the experimental data. It is also necessary to draw the forward volt-ampere characteristic curve of the diode, and obtain the reverse saturation current I0 and the ideal factor n.

If you've completed the steps described above and you're getting the correct result, you're not done, so continue:

When the current in the diode is constant, the current of the diode is set to be 5μA, 15μA, and 20μA respectively, and the relationship between voltage and temperature is determined, and the diode voltage Vg(0) at absolute zero is deduced, and the characteristics and causes of the diode forward junction voltage obtained at absolute zero are analyzed under different constant current conditions.

The above are the stem requirements given on the experimental answer sheet.

This experimental question is not difficult, but 80 points is not so easy to get all, in addition to the steps and results written on the answer sheet need to ensure accuracy, the practical behavior of the contestants is also counted in the scoring or deduction items.

The invigilator patrols the laboratory and records the practical behavior of each contestant, and one-on-one monitoring is not possible, and there are not so many invigilators. Generally, an invigilator keeps an eye on several players around, so today's experiment is divided into two sessions: morning and afternoon, and the contestants are triaged.

Shen Qi has practiced under the guidance of Mu Rong and practiced electrical experiments.

The experimental questions in the semi-finals are also electricity, and the finals are still.

Because the electrical test equipment is easy to obtain, the experimental results can be verified on the spot, and it is easy to set up as a competition experiment.

Each contestant has a particle accelerator, and the Chinese Physical Society does not have the ability and financial resources to organize it, and the headquarters of the Chinese Physical Society has a particle accelerator, which is still second-hand.

Shen Qi first used the bridge method to draw the measurement circuit diagram, and then set the temperature of the water bath to 27 degrees.

Connect the circuit according to the circuit diagram, adjust the initial value of the potentiometer, make the output voltage of the voltage divider circuit 0, set the value of the resistance box to 10,000 Ω, and adjust the galvanometer to zero.

After doing these basic experimental preparations, Shen Qi turned on the power supply and slowly adjusted the potentiometer to increase the ammeter reading.

Continue to adjust and repeatedly adjust the potentiometer and resistance box to balance the bridge at the set voltage value.

Then Shen Qi drew a record form on the answer sheet to record the data.

The voltage is 0.430V, and the current is 0.52μA

The voltage is 0.441V, and the current is 0.77μA

……

Twenty sets of data were recorded, and Shen Qi drew the forward volt-ampere characteristic curve of the diode based on these data, and calculated the reverse saturation current I0=3.397×10^-14A, and the ideal factor n=1.001.

The first small part of this experiment is done.

Up to this point, high school students need to master the basic electrical experimental operation, as well as the basic ability of data recording, processing, and calculation.

Therefore, the experimental link can't pull away the scores, let alone the physical candidates, ordinary high school students, the kind whose physics scores are so-so, and their hands-on ability is okay, and it is no problem to complete the first small part of the national final experimental questions.

The second part is a little more cumbersome.

It is actually a theoretical derivation problem to deduce the diode voltage Vg(0) at absolute zero, and analyze the characteristics and causes of the diode forward junction voltage at absolute zero obtained under different constant current conditions.

The CPhO test comes and goes, and to put it bluntly, it is a test of theoretical knowledge.

After theoretical derivation and calculation, Shen Qi concluded that the values of Vg(0) at infinitely close to absolute zero are 1.225V, 1.233V, and 1.244V, and these three voltage values correspond to the current values of 5μA, 10μA, and 15μA, respectively.

This concludes the experiment.

Including Shen Qi, many contestants successfully completed the experiment and answered the questions.

The scores of the lab questions were released on the same day.

None of the contestants scored a perfect score of 80 for the experimental questions, and the highest score was 79.5 points.

In the practical action, each player was more or less deducted a little point.

There is no way around it, there is no standard posture for practical movements, and no one dares to guarantee that every detail of themselves is perfect.

Shen Qi's experimental score was 77 points, and 3 points were deducted. He could accept the result.

The experimental score is out, which means that the total score of this year's CPhO national final has been finalized.

The Chinese Physical Society announced the overall score ranking of each contestant:

1. Shen Qi (Nangang No. 2 Middle School), 357 points;

2. Tang Mengqi (Changjun Middle School), 352.5 points;

3. Su Xiaolie (No. 1 High School Attached to China Normal University), 352 points;

4. Lu Huaisong (Suzhou and Hangzhou No. 2 Middle School), 350.5 points;

5. Ma Zixin (Yali Middle School), 349 points;

5, Han Xuance (Shijiacun No. 2 Middle School), 349 points

7. Jin Shengqiang (Special Zone Middle School), 348.5 points;

……

200, Zeng Luna (Northeast Yucai School), 112 points.

The total score is only published to the top 200, of which the top 50 will win the national first prize, 51-200 will win the national second prize, and 201-412 will be the third prize.

The national gold medal score line was drawn to 282 points, which is the score of the 50th-ranked player.

The national training team scored 298 points, which is the score of the player who ranked 40th.

When the dust settled, 50 players won the gold medal of the first national competition, of which the top 40 gold medalists were selected for the national training team.

As in previous years, the top 50 contestants are basically from domestic schools that are strong in physical competition and discipline competition.

Except for Shen Qi, who ranked first.