The polarity of the magnet was determined, and everyone flocked to Sun Yi to return to the "laboratory". Pen | fun | pavilion www. ｂｉｑｕｇｅ。 ｉｎｆｏ

Sun Yi took two thick copper wires, threw them on the ground and rubbed them repeatedly with the soles of his shoes, and then picked them up, which were two straight copper wires.

After finding a wooden plank, Sun Yi bent two copper wires into a zigzag shape and fixed them parallel to the plank, turning them into a copper parallel bar.

Then he made a slightly shorter straight copper wire, and Sun Yi leaned over with a magnet. Repeated several times, the copper wire did not react at all.

Sun Yi explained: "Magnets can't absorb copper. ”

Sun Yi connected the parallel bars to the two poles of the battery, and put the straight copper wire on the parallel bars, saying: "Don't look at this as a copper wire, it is also a small electromagnet when it is electrified, and it can also attract and repel other magnets." ”

Sun Yi held a magnet and pressed it against the top of the straight copper wire. I saw the copper wire move slightly, and then it fled to the side until it rolled off the parallel bars.

Sun Yi put back the copper wire, dropped the polarity of the magnet in his hand, and then approached the copper wire, this time the copper wire rolled down in the other direction.

Sun Yi said: "Using this method, we can detect whether there is any current in the copper wire, and we can also judge the direction of the current."

Sun Yi didn't plan to talk about the left-handed rule and the right-hand rule, he couldn't remember those things after studying science and engineering for more than ten years, and the current of the Ming Dynasty was still the opposite of later generations. It's good to explain it with an electromagnet with a single wire.

Sure enough, the people of the Ming Dynasty immediately accepted Sun Yi's explanation, and with the excited experiments of the Ming people, they quickly summed up the relationship between the direction of the magnetic pole, the direction of the current and the direction of the copper wire rolling off.

Taking advantage of the Ming Dynasty's kung fu of playing copper wire parallel bars, Sun Yi checked the remanence of the "soft iron" electromagnetic core, and could only say that it could barely be improvised, so Sun Yi made a pair of copper wires of "soft iron electromagnets" - using the reverse magnetic field to degauss.

On a large board of wood, Sun Yi fixed the battery, the "flexible iron electromagnet", and also fixed a special copper sheet.

This copper sheet is made of bronze, which is to be hard. At one end of the copper sheet, Sun Yi soldered a piece of iron with tin. The position of the iron block is directly in front of the electromagnet.

Sun Yi adjusted the distance between the electromagnet and the copper sheet, and whenever the electromagnet was energized, the iron on the copper sheet would deviate towards the electromagnet with the copper sheet until it was blocked by the electromagnet. And once the electromagnet is disconnected, the copper plate bounces back quickly until it is blocked by another copper plate.

Sun Yi changed the wiring method and connected the electromagnet and the two copper sheets in series.

Turning on the battery again, there was a "buzz", and the bronze piece welded with iron bobbed back and forth as if it were convulsed, looking like the wings of a flying bee. The electromagnet was whipped by the bronze sheet and emitted a continuous "da-da", as if shivering.

It's done!

Sun Yi put up the only gong in the camp, "Zero, Zero, Zero, ......Zero, Zero", and the iron on the bronze piece struck the gong, making a crisp and dull bell.

Sun Yi let go of the hand holding the gong, "Ding Ding ......", and the bell sounded high-pitched until the bronze piece hit the gong out of reach.

The craftsmen next to him were attracted by the bell and ran to investigate.

Sun Yi said "modestly": "A gadget can also measure current." The principle is the same, it is an electromagnet. ”

Sure enough, the people of the Ming Dynasty didn't think that this was a "gadget", and when they figured it out, it was actually an automatic switch on and off of an electromagnet, and the craftsmen all praised Liddell's exquisite thoughts!

When this device reaches the hands of professional craftsmen, it immediately radiates great power.

Not only did the craftsmen re-fix the elements, but they also suspended the gongs, welded hammers with more powerful blows, and arranged special "electric gates".

When the electric door is pressed, "Boom ......", a loud voice sounds.

The craftsmen said, "It's called an electric gong!" ”

Sun Yi didn't know whether the gongs were smart or stupid, and after a while they connected the circuit in reverse, and when they pressed the electric door, the gong hammer was sucked on the electromagnet and couldn't come down, and it didn't vibrate at all. They simply removed the gong and installed it on the other side, so that when the electric door was pressed once, the gong would ring.

Sun Yi commented, "You might as well use a wooden stick to knock it directly!" ”

But a few of them were very addicted, constantly adjusting to make the gong louder and louder.

Finally they announced, "It's called an electric clock!" ”