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Anonymous users2024-02-151. Why do the stars twinkle and twinkle?
We see the stars shining, not because of a change in the luminosity of the stars themselves, but because of the occlusion of the atmosphere. The atmosphere is separated from us and the stars, and when starlight passes through the atmosphere, it is affected by the density and thickness of the atmosphere.
The atmosphere is not absolutely transparent, and its transparency varies depending on the density. So if we look at the stars through it on the ground, we will see that the stars seem to be flickering.
2. Why do sunflowers always bloom towards the sun?
The place under the stem of the sunflower flower disc contains a substance called auxin. This substance has the function of speeding up reproduction, but it has the ability to resist rotation, and whenever it encounters light, it will run to the backlit side.
So when the sun rises, the sunflower stems immediately hide on the backlit side, and it looks like the whole plant is bent in the direction of the sun.
3. Why do fireflies glow?
Fireflies emit light because of the luminaires at the end of their abdomen, which are filled with many phosphorus-containing luminescent substances and light-emitting enzymes, which allow fireflies to emit flashing light.
The purpose of fireflies to glow, in addition to lighting, also has courtship, vigilance, trapping and other purposes. It is also a communication tool for different species of fireflies, which can convey different messages in different ways, frequencies and colors.
4. Why do squirrels have particularly large tails?
While the squirrel is jumping around the tree, its tail is playing a big role. It allows the squirrel to balance when jumping over a tree, preventing it from falling and getting hurt. In addition, this large tail can play a protective role in winter, tightly surrounding the squirrel's body, which is both convenient and practical.
5. Why is most of the sea water blue and green?
When you look at the sea, you can often see that the water is blue and green. However, when you scoop up the seawater, you can only see that it is as transparent and colorless as the water of the past. It turns out that the sea water itself is not much different from the water we come into contact with every day, and it is also transparent.
The green color we see is actually a phenomenon produced by the ability of sea water to absorb light. Only green light can be absorbed by seawater and thus reflected; When the water is deeper, the green light is also absorbed, and the water looks blue.
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Anonymous users2024-02-142. (Magnifying glass) is widely used in many aspects of people's life and production.
3. The characteristics of magnifying glass lenses are (transparent) and (thicker in the middle) (convex). As long as it has a transparent magnifying lens and a thick structure in the middle (such as a beaker, flask, etc. after filling with water), it has the same (magnification) function.
4. The magnification of the magnifying glass has nothing to do with (the diameter of the lens), but (the convexity of the lens). magnifying glass (the greater the convexity, the greater the magnification).
5. Using tools can observe many (details) that cannot be observed with the naked eye. More details about insects can be observed through a magnifying glass: flies (compound eyes); The ears of the cricket are on (the inside of the foot); The small colored scales covered with butterfly wings are (flat fine hairs).
6. Scientific studies have shown that the antennae on the head of insects are their ("nose"), which can distinguish various odors and are much more sensitive than human noses.
7. (Some solid substances) have a certain internal structure, if the particles that make up these substances are arranged in a certain spatial order to form a (regular geometric shape), this is (crystals), such as salt, sugar, etc.
8. The combination of two (convex lenses) can make the object's (image larger).
9. The invention of the microscope is a great leap in human understanding of the world, bringing human beings into a (microcosm). The microscope is an important observation tool for human understanding (the tiny world).
10. The Dutch biologist (Leeuwenhoek) made the world's first microscope that can be magnified nearly 300 times and discovered (microorganisms).
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Anonymous users2024-02-13Popular science knowledge content for primary school students:1.The world's largest glacier is in Antarctica.
2.The largest freshwater lake in the world is Lake Superior.
3.The largest square in the world is Tiananmen Square in China.
4.The world's largest seated Buddha is located in Sichuan, China.
5.The largest palace in the world is: the Forbidden City.
6.The world's largest and most expensive diamond is hidden in the British royal family.
7.The largest encyclopedia in the world is the Yongle Canon
8.The largest island in Europe is the island of Great Britain.
9.The largest peninsula in Europe is Northern Europe.
10.The largest commercial bank in China is the Industrial and Commercial Bank of China.
11.The grottoes of China's largest classical art library are the Mogao Grottoes in Dunhuang, Gansu Province.
12.China's largest production base of commercial soybeans and export soybeans: Northeast China.
13.The largest freshwater lake in China is Poyang Lake.
14.The largest collection of poems in China is "All Tang Poems", which contains more than 48,000 poems from the Tang Dynasty.
15.The largest inland saltwater lake in China is Qinghai Lake.
16.The largest lake in China is Qinghai Lake.
17.The Taklamakan Desert, the largest desert in our country, is located in the Tarim Basin.
18.The largest producer of diamonds is: Zaire.
19.The largest lake on the Yunnan-Guizhou Plateau is: Dianchi Lake.
20.The largest transport system in Moscow is the Metro.
21.Among the mammals, the largest is the blue whale.
22.The northernmost capital of the world is: Reykjavik.
23.The longest mountain range in the world is: the Andes.
24.The longest narrative poem in the world is The Legend of King Gesar
25.The best coffee in the world is produced in Jamaica.
26.The country that produces the most corn in the world is: the United States.
27.The windiest place in the world is Antarctica.
28.The river that flows through the most countries in the world is the Danube.
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