Naturally, Zhuge Liang and Sima Yi more or less had some suffocation when they were using soldiers.

can't be like Jia Xu from beginning to end to ensure that he will not suffer.

So after a period of careful study, Wu Zhen was convinced that Jia Xu was the first wise person in the Three Kingdoms.

Although Li Dao Guo Yan's counterattack on Chang'an did cause the central government of the Eastern Han Dynasty to completely lose control, no one is perfect, and no flaws are hidden, otherwise Jia Xu's story is likely to end.

In books, physics class became the most difficult content.

The circuit diagram experiment questions make people break down.

Fortunately, Mr. Xiao announced that the next physics class will be an experimental class.

Naturally, everyone was very happy to hear this.

After all, after going through chemistry classes, the laboratory has become the most desirable place for everyone.

Therefore, Wu Zhenzhen also did a very serious job of previewing the experiments in the textbook.

Although it was already known that the voltage of a No. 5 battery was 1.5V, Wu Zhenzhen was still looking forward to the next test.

After all, the black ammeter and voltmeter in the book are interesting.

However, when it came time to do the experiment, it was not so happy.

When I walked in front of the laboratory, I saw a voltmeter and an ammeter that had already yellowed a little.

Naturally, the simplest test of the voltage of the No. 5 battery began first.

It's a fairly simple experiment.

The results are naturally concentrated in the range of 1.44~1.51V.

Then, we started to connect according to the simple circuit diagram on the blackboard.

Then he counted the other items on the table—a small bulb shelf, a switch, and a battery pack power supply.

Naturally, even after previewing, Mr. Xiao still emphasized: "The voltmeter must be connected in parallel to the circuit, and the ammeter must be connected in series." ”

However, among the simple circuits that have been assembled, there are still many people whose circuits do not light up after the switch is pressed.

From time to time, someone raised his hand and asked, "Why did I turn on the switch and the two meters reached the top?"

Naturally, this is because both series and parallel meters are ammeters.

As a result, Mr. Xiao had to stop the test first and said, "Everyone, pay attention, remember to turn off the switch when the current indication exceeds the range." This is because this may burn the ammeter. ”

After a pause, Mr. Xiao continued: "The current indication exceeds the range, which means that the indication of the ammeter is from the far left to the far right of the meter. Raise your hand when this happens, and I'll come to help. ”

Naturally, Wu Zhenzhen did not have these problems, and soon completed the recording of the test data.

After all, connecting a power supply, an ammeter, a voltmeter, a switch, and a light bulb is indeed a very simple circuit.

It just so happened that Guo Xue's things at the same table were also done, so the two looked at each other, ready to start making more complex circuits, that is, two power supplies in series, two bulbs in parallel, and two switches were set in front of the two bulbs.

Of course, the ammeter is placed on the trunk and the other in front of the bulb, after all, the ammeter is also placed in front of the bulb, so it doesn't make much sense, after all, the specifications of the two bulbs are the same.

Naturally, there is still only one voltmeter, after all, the two bulbs are connected in parallel.

So, by adjusting the switch, a series of data is obtained.

For example, when both switches are pathways, the number of current representations on the backbone is exactly twice as high as the number of current representations for the splits.

After turning off the other switch, the indication of the two ammeters becomes the same, both of which are the same as those of the previous shunt ammeter, and at the same time, the light is brighter.

When both switches are turned off, the ammeter becomes zero.

However, no matter what the situation, it seems that the voltmeter has not changed, and it has always been the voltage of the two No. 5 batteries.

So, Wu Zhenzhen and Guo Xue fell into thinking.

Naturally, after completing this operation, it was almost time to pack up the experimental class.

Mr. Xiao said: "Okay, the time is almost up, please disassemble the circuit and restore it." ”

So, after carefully looking at the circuit diagram again, Wu Zhenzhen and Guo Xue began to disassemble the circuit.

It seems that this time it was tighter and the wires were more laborious to remove.

However, in the end, the dismantling was completed.

Back in the classroom, the two continued to think.

Wu Zhenzhen asked: "Why has the number of voltage representations not changed, but the two bulbs of the parallel circuit are not as bright as the bulbs in series?

Guo Xue thought about it and said, "Haha, yes." I have this problem too. ”

So, the two went into the physics office again.

Naturally, the physics office has always been a door, so I was very happy to see a boy and a woman who were about the same height.

Then, the two of them drew the circuit diagram.

When Mr. Xiao saw it, he immediately smiled and said, "Is there anything wrong with such a simple circuit diagram?"

Wu Zhenzhen immediately said: "It was connected according to this circuit diagram in our previous experimental class." ”

Then the main circuit of a power supply and two bulbs in parallel is explained, of course, there is a switch on each of the two splitters with bulbs, and the ammeter is located on the shunt and bus respectively, and the voltmeter is connected to both sides of the bulb.

Then, Guo Xue immediately said: "We mainly had a problem when we were doing this experiment. That is, when we only turn on one light, we find that the light is relatively bright. However, when both lights were turned on, it was darker. ”

Teacher Xiao said, "Well, then what?"

Wu Zhenzhen immediately said: "In this process, the indication of the voltmeter and ammeter has hardly changed, but why does this light dim?"

Mr. Xiao immediately laughed and said, "Haha, the voltage of parallel connection is actually a little smaller, and it can be seen if you use a voltmeter with a thinner range."

After a pause, Mr. Xiao continued: "It is possible that the voltage of the power supply is just at a critical point. If the voltage is a little higher, the bulb will light up, and if it is a little lower, it will dim, so the bulb in front of you will have such a problem. ”

Wu Zhenzhen said: "That means that the voltage will change in this case?"

Mr. Xiao smiled and said: "That's right, the voltage will change, but the amplitude of the change is generally very small, so generally speaking, we think that the voltage is certain, and the current is also certain when the resistance is certain." However, the ammeter is theoretically free of resistance, so it will have a certain impact on this result. ”。

After a pause, Mr. Xiao continued: "However, with the change of temperature, the resistance of matter will change, so don't delve into this thing, and this kind of trivial details is not the content of junior high school physics. Let's go back to high school. ”

In this way, the two of them understood that in this process, the voltage and current have changed, but the change is not very large.