How to write a composition after the invention of compass?

1. Ask for an article about the invention of the compass. Magnets were not invented by people. There are natural magnetite, and China should be the first to make effective use of magnets.

Therefore, the compass is one of the four great inventions of China people. As for the composition, it is iron, cobalt, nickel and so on. Its atomic structure is very special. The atom itself has a magnetic moment. Generally, these mineral molecules are arranged in disorder. When magnetic fields interact, they do not show magnetism. However, under the guidance of external force (such as magnetic field), the direction of molecular arrangement tends to be the same, which is called a magnet. Iron, cobalt and nickel are the most commonly used magnetic substances. Basically, magnets are divided into permanent magnets and soft iron permanent magnets, which combine strong magnetism to make the spin of magnetic substances and the angular momentum of electrons in a fixed direction. Soft iron combined with current (also a method to increase magnetic force) When the soft iron is removed by equal current, it will gradually lose its magnetism. As for the earliest magnet, who found that the oldest record was China Huangdi vs Chiyou's South Compass, so it was called one of the four great inventions in China! China knew about magnetic polarization in the first century BC.

During the Warring States period, a natural magnet was placed on a graduated copper plate for divination. During the Northern Song Dynasty, there were two ways to make artificial magnets. One is to place the red-hot iron needle in the north-south direction, and after rapid cooling, the iron needle is magnetized by the earth's magnetic field. The other is made by rubbing an iron needle with a magnet.

Meng Qian Bitan recorded the existence of magnetic declination, and found that under the influence of magnetic declination, the magnetic needle pointed to the south, slightly to the east than the real south. Based on this knowledge, the scientific application of magnets as compasses has been developed.

Magnet is just a general term, which refers to something with magnetism. The actual composition does not necessarily contain iron. Pure metallic iron itself has no permanent magnetism, and it will be induced to produce magnetism only when it is close to a permanent magnet. Generally, other impurity elements (such as carbon) are added to the permanent magnet to stabilize the magnetism, but this will reduce the freedom of electrons and make it difficult to conduct electricity, so the light bulb will not light when the current passes.

Iron is a common magnetic element, but many other elements are more magnetic. For example, many powerful magnets are made of rubidium, iron and boron. [Edit this paragraph] Basic knowledge The ancient Greeks and China discovered a naturally magnetized stone in nature, called a "magnet". This kind of stone can magically pick up a small piece of iron and swing it at will and always point in the same direction.

Early navigators used this magnet as their earliest compass to tell directions at sea. After thousands of years of development, magnets have become a powerful material in our life today.

By synthesizing alloys of different materials, we can achieve the same effect as magnets and improve the magnetic force. /kloc-artificial magnets appeared in the 0/8th century, but the process of making stronger magnetic materials was very slow, and Al-Ni-Co was not produced until the 1920s.

Subsequently, ferrite was made in 1950s, and rare earth magnets (including NdFeB and SmCo) were made in 1970s. At this point, magnetic technology has developed rapidly, and ferromagnetic materials have also made components more miniaturized.

[Edit this paragraph] Magnetization (orientation) direction Most magnetic materials can be magnetized to saturation in the same direction. This direction is called "magnetization direction" (orientation direction). Non-oriented magnets (also called isotropic magnets) are much weaker than oriented magnets (also called anisotropic magnets).

What is the standard industrial definition of "North and South Pole"? The definition of "North Pole" is that after the magnet rotates at will, the North Pole points to the North Pole of the Earth. Similarly, the south pole of the magnet also points to the south pole of the earth.

How can you tell the north pole of a magnet without labeling it? Obviously, eyes alone can't tell the difference. You can use a compass to get close to the magnet, and the pointer pointing to the north pole of the earth will point to the south pole of the magnet.

How to handle and store magnets safely? Be very careful, because magnets attract each other and may pinch your fingers. When magnets attract each other, they may also be damaged by collision (knocking off corners or cracking).

Keep the magnet away from easily magnetized objects, such as floppy disks, credit cards, computer monitors, watches, mobile phones, medical devices, etc. Magnets should be kept away from pacemakers.

For larger magnets, plastic or cardboard washers should be added between each magnet to ensure that the magnets can be easily separated. Magnets should be stored in a dry and constant temperature environment as much as possible.

How to achieve magnetic isolation? Only the material that can be adsorbed on the magnet can isolate the magnetic field, and the thicker the material, the better the magnetic isolation effect. What is the strongest magnet? At present, the magnet with the highest performance is rare earth magnet, and NdFeB is the magnet with the strongest performance among rare earth magnets.

But in the environment above 200 degrees Celsius, samarium and cobalt are the strongest magnets. [Edit this paragraph] Types of magnets Magnets should be called magnetic steel. Magnetic steel is now mainly divided into two categories, one is soft magnetic and the other is hard magnetic; Soft magnetic includes silicon steel sheet and soft magnetic core; Hard magnets include Al-Ni-Co, Sm-Co, Ferrite and NdFeB, among which Sm-Co is the most expensive, Ferrite is the cheapest and NdFeB has the highest performance, but Al-Ni-Co has the most stable performance and the best temperature coefficient. Users can choose different hard magnetic products according to different needs.

How to define the performance of a magnet? There are three main performance parameters that determine the performance of the magnet: remanence Br: The permanent magnet is magnetized to technical saturation, and the retained Br is called remanence induction intensity after the external magnetic field is removed. Coercive force Hc: To reduce the B of a permanent magnet magnetized to technical saturation to zero, the required reverse magnetic field strength is called magnetic induction coercive force, which is referred to as coercive force magnetic energy product BH for short: it represents the magnetic energy density established by the magnet in the air gap space (the space between the two poles of the magnet), that is, the static magnetic energy per unit volume of the air gap.

Because this energy is equal to the product of Bm and Hm of the magnet, it is called magnetic energy product. Magnetic field: the space that produces magnetic effect on the magnetic pole is the magnetic field. Surface magnetic field: how to choose the magnet for the magnetic induction intensity at the specified position on the surface of the permanent magnet? What role should the magnet play before deciding which kind of magnet to choose? Main functions: moving objects, fixing objects or lifting objects.

Required magnet shape: disc, ring, square, tile or special shape. Required magnet dimensions: length, width, height, diameter and tolerance, etc.

The attraction of the required magnet.

2. Who invented the compass? The first kind of compass is the sun.

We live in the northern hemisphere. Except in the south of the Tropic of Cancer, the sun always shines from the south. In this way, the north-south direction can be easily determined. We all know that the sun rises in the east and sets in the west. The sun rises in the east in the morning, sets in the west at night, and is in our south at noon.

However, you should not apply this method dogmatically. If you are in the southern hemisphere or between the Tropic of Cancer, the situation is another matter.

The second kind of compass is the moon.

On the third and fourth day, the crescent moon, the sunset is low in the west; On the eighth day of the seventh lunar month, the sun just went down, just above our heads. In half a month, as soon as the sun goes down, the moon rises in the east.

The direction of the moon at night is: the first quarter moon, in the south at 6 pm, and in the west at 12 pm. The full moon (14-18) is in the east at 6 pm, in the south at 12 pm, and in the west at 6 am the next day. First quarter moon, in the east at night 12, and in the south at 6 o'clock the next morning.

The third kind of compass is Polaris.

Polaris is the best compass, and its direction is due north.

But how to find Polaris? In fact, it is easy to find the familiar Big Dipper. The Big Dipper is like a water spoon. When the two stars on the side of the water spoon are stretched to about 5 times, there is a brighter star, the Polaris.

On the opposite side of Polaris, there is also a constellation Andromeda, shaped like the English letter W, which can also help us find Polaris.

Around 8 pm, if February-August, February 2- 10/October, you can use Ursa major to find Polaris, and Cassiopeia is better.

The fourth kind of compass is trees.

This method is also very simple. For example, north of the Tropic of Cancer, the sun shines from the south, and the trees in the south get more heat from the sun than the trees in the north. Therefore, the branches of independent trees grow luxuriantly to the south and sparsely to the north.

It can also be distinguished by tree rings. These rings face south in width and north in density. Because the south grows faster than the north, the annual ring interval is wider.

The fifth kind of compass is snow.

Similarly, take our northern hemisphere as an example. The snow on the southern hillside is denser and more granular. The snow on the northern hillside is softer and drier.

When the snow melts, the snow on the south hillside melts more easily than the snow on the north hillside.

3. How to write a small compass composition? Give me the right answer. I have a special gift-compass. On Sunday, when my father and I visited my sister who was studying abroad, my sister gave me a beautiful gift.

When my sister put the compass in my hand, she told me again and again, "You should put it in your pocket so that you won't get lost and get separated from your parents when you go out." I said thank you to my sister, but the thoughts in my heart brought me to the scene of visiting Tongbai Mountain on May 1 this year.

I followed my father and several uncles to visit water curtain cave in Tongbai Mountain. When we walked halfway up the mountain, I was very curious, so I told them several adults: I'll climb up from the mountain and go around the parking lot in front. (Because, I have been there once) Although I didn't get their permission, I climbed the hillside alone. When I meet a flat place, I run a few steps; When I meet a steep place, I use all my limbs. When I climbed to a flat rock, I was exhausted. I had a rest and got up quickly for fear that they would leave me behind. The higher I climb, the steeper I climb. Fortunately, some thorns and small trees grew on the edge of the cliff, which helped me. When I went to the parking lot, I didn't see any. Later, I learned that they had arrived, and they could not wait for me, so they went to find me separately!

When I get home, my father will inevitably give me a "political lesson". And my sister heard it. She only said one sentence at that time: "Let my brother go out with a compass in the future, so as not to get lost." It was not until today that my sister put the compass in my hand that I realized that my sister's concern and concern for me had been buried in my heart. So, I took the compass my sister gave me as a treasure and carried it with me.

I think: the compass my sister gave me is not only in the outside world, but also won't let me lose my way; You can't get lost in your study. When I can't calm down in my study, I touch the compass in my trouser pocket and think about my sister's love for me. I can't betray her love. So, I settled down to choose the right direction and study hard.

Dad bought me a compass. It's black and round. When it is picked up, it will keep turning. It's so cute. No matter where I stand, the red arrow always points to the south, so that I can easily know the direction of my position.

I also heard from my father that the compass was one of the four great inventions in ancient China. Because of the compass, the navigator will not get lost and can sail the ship to the destination; Because of the compass, explorers won't get lost and can walk out of forests and deserts safely. Dad's car has a navigation system with a small compass on it.

How convenient the intelligent inventions of ancient people have brought to us modern people!

My family has a compass, which is one of my best friends.

I bought this compass from my mother for 20 yuan the last time I played table tennis. This has always been my dream. Now, I finally have it. I was so happy that I couldn't sleep that day.

Compass, everyone sounds familiar. This is one of the four great inventions in China. From the square disk and spoon-shaped Sina in Han Dynasty to the small and exquisite compass and compass now, it has undergone many changes. My compass is round, with a diameter of 5-5 cm. My obedient pointer points to the south, and a piece of lead drawing paper is marked with east, west, north and south. The angle is drawn on the inner edge of the compass. If there is no pointer, it seems to be a running ground.

I always play tricks on the compass and put a magnet next to it. As a result, it ignored the magnetic field and followed the magnet. Because it is confused by my magnet, and I am a strong magnet, the compass is in close contact with my magnet. Then I sucked it with the opposite magnet, and it ignored me. It turns out that this is because magnets with the same magnetic poles will separate when they touch each other.

This is my compass. I really like it!

The compass, one of the four great inventions in China, I think everyone knows it! Who invented it? According to this book, it was invented by the working people in China.

But what is its internal structure? I want to find out. So I bought a cheaper compass, took its plastic shell apart, and found that there was a magnetic needle in it, which was inserted vertically in the black case, and just put a flat magnetic sheet on the magnetic needle.

So, I also did a similar experiment: I first measured its positive and negative poles with a magnet, and then sucked a staple that I broke straight on it, and then sucked the magnetic disk from the original compass on it, but the magnetic needle just didn't move. What's going on here? It turns out that the head of the staple is not pointed, so the head of the compass must be pointed. I thought the principle of the compass was simple, but I didn't expect there was so much knowledge in it.

My mother watched me concentrate on studying the compass and said to me, "I have read a message about the compass before." The method is: put the sponge on the water, and then put a needle on the sponge. "I did as my mother said, and everything went well in the experiment.

Although this simple compass can be used as a guide, this method has many disadvantages, such as no slight magnetic force, no ripples on the water surface and no water. ...

How exactly are magnets formed? What does it do? How can we be used? I may not be able to solve this mystery at this stage, but I have a preliminary understanding of it. I believe that as long as I work hard, I will gain something and this mystery will be solved by me.

How to write a composition about the four great inventions Since the birth of the four great inventions, their creators have all become immortals. They have a treasure, which has a strong magnetic force. Unfortunately, the treasure was stolen, so they sent their pets, namely compass, papermaking, printing and gunpowder. They have begun to look for treasure. First of all, the police dog: the compass smells the treasure. The soldier wouldn't let him in, and then he was sweating: gunpowder blew up the city gate. When he entered, he couldn't find the thief. At this time, Zhi Duoxing: Papermaking wrote the method on paper, but he couldn't see it. Another one appeared. Yes, the printing factory has made three copies of this method. He found the thief and got the treasure back. After returning, the creator asked: Who played a role in the construction? The compass said, it's me, but for me, they can't find the thief. Gunpowder said discontentedly, it was obviously me, but for me, they couldn't have entered the city gate at all. Paper-making said angrily, if I'm not smart, you can't help it. Only India said: Don't argue, everyone has a credit. The creator said: You should be as modest as printing. Since then, the four great inventions have become best friends.

6. I think everyone knows the compass, one of the four great inventions in China! Who invented it? It is recorded in the book that 323131335323635438+03431303231363533e 78988e 69d8331333373566 was invented by working people in our country.

But what is its internal structure? I want to find out. So I bought a cheaper compass, took its plastic shell apart, and found that there was a magnetic needle in it, which was inserted vertically in the black case, and just put a flat magnetic sheet on the magnetic needle.

So, I also did a similar experiment: I first measured its positive and negative poles with a magnet, and then sucked a staple that I broke straight on it, and then sucked the magnetic disk from the original compass on it, but the magnetic needle just didn't move. What's going on here? It turns out that the head of the staple is not pointed, so the head of the compass must be pointed.

I thought the principle of the compass was simple, but I didn't expect there was so much knowledge in it. My mother watched me concentrate on studying the compass and said to me, "I have read a message about the compass before."

The method is: put the sponge on the water, and then put a needle on the sponge. "I did as my mother said, and everything went well in the experiment.

Although this simple compass can be used as a guide, this method has many disadvantages, such as: no slight magnetic force, no ripples on the water surface, no water ... how is the magnet formed? What does it do? How can we be used? I may not be able to solve this mystery at this stage, but I have a preliminary understanding of it. I believe that as long as I work hard, I will gain something and this mystery will be solved by me.

7. Composition is a small compass. After school on Friday, the teacher asked us to go home and make a small technology product.

When I came home from school, I sat at my study desk and thought hard about what I should do. Still muttering. Then my father appeared in front of me and said kindly, "I'll give you a suggestion, compass." Dad gave me a book to learn how to do it. I found an iron needle first, and the book said that the needle should be magnetized first. How can I magnetize the needle? Dad said, "Put this iron needle on the magnet and rub it repeatedly." Dad also reminded me to rub in the same direction. I did as my father said, and sure enough, the needle was magnetized. I found the wheel of a toy racing car as the base of the compass, and installed a needle as a bracket on the base. I took another small wheel and fixed the magnetized needle on it with tape. Note that the two sides should be equal and the length should be the same, so as to balance. Put the fixed needle on the bracket so that the compass is ready. With a slight push, the compass turns. When it stops, one end points to the south and the other end points to the north. I asked curiously, "Why is this?" Dad said, "Because our earth is a big magnetic field, the South Pole is the positive pole and the North Pole is the negative pole. According to the principle that like magnetic poles repel and opposite magnetic poles attract, the negative pole of the magnetic needle always points to the south, understand? " Oh, the principle is like this, it's amazing!

This small production not only made me learn scientific common sense, but also made me feel the fun of doing it myself!

8. Making Compass Composition China's four great inventions are the pride of each of us in China. Compass is one of the four great inventions. Since ancient times, we have needed a compass to guide us to sail at sea, fly in the air and travel on land. Today, I will make a simple compass.

Our thinking textbook has taught us how to make a simple compass, so I will follow it. First, I took a needle, then an alcohol lamp, then a wire and a plastic cup, and finally a bowl of ice water.

These are all materials that must be used. I tied the needle with iron wire first, and then put it in a burning alcohol lamp to burn it red.

Then immediately put it into water to cool, so that the needle faces north and south. At this time, there can be no mistakes. This is the simple process of making a small magnetic needle.

Next, you need to make a small hole in the bottom of the plastic cup. One end of the thin wire is tied in the middle of the needle and the other end passes through the small hole. However, the sewing needle was slippery and slipped off the tied thread several times. After many failures, I finally found the balance point of the needle and carefully wound the thin thread, completing this key step.

Finally, the step of needle insertion is completed. The next step is to carefully thread the needle through the plastic cup and tie it to the bottom of the cup with a thin thread for needle insertion. After this, I turn the plastic bottle upside down, huh? Really, as the textbook says, one end of the small magnetic needle points to the south and the other end points to the north.

Making this compass by myself not only finished my homework, but also improved my hands-on ability. It's killing two birds with one stone.