Ask for a 1000 word popular science essay, a 1000 word popular science essay

The other day, I bought a small goldfish and it's so cute. The little goldfish is silver-gray all over, with bulging eyes like small light bulbs, and the most endearing thing is that it also wears a flared skirt. As it swims, this "flared skirt" is like a lotus flower in full bloom, and I love it so much.

Every time I come home from school, the first thing I do is feed the baby goldfish. When I was about to sprinkle the food to it, it seemed to know that I was going to feed it, so it swam towards me, I sprinkled the fish food on the surface of the water little by little, and the little goldfish ate it bite by bite, and when it was full of food and drink, it swam freely in the water, at this time, a question mark suddenly flashed in my head, why can fish only live in water?

I really wanted to understand this question, so I asked my mother, who only told me that fish breathe by gills. Is it possible for a fish to live in the water by breathing by gills? I decided to go online after all.

Nowadays, technology is really advanced, and it didn't take long for me to find the answer. It turns out that the gills of fish are only adapted to absorb oxygen from the water, but not to the air, and the shape of the fish is more adapted to life in the water. The surface of its body is covered with scales to protect the body, and there is a layer of mucus on the surface of the scales, which reduces the resistance of the water when swimming, no wonder, every time you pick it up with your hands, you feel that it is slippery.

In addition, there is a line of lateral lines on both sides of its body, which are connected to the nerves, mainly to determine the direction and sense the flow of water. In addition to swimming "tools" such as pectoral fins, dorsal fins, pelvic fins, and caudal fins, fish also have swim bladders in its body, and by adjusting the air capacity in the swim bladder, they can float and sink freely in the water.

I finally figured out why fish can only live in the water, and at the same time satisfied my curiosity. Since then, I like my little goldfish even more! Every time I watch it swim freely, I fall into an endless reverie:

If one day a person has gills and a swim bladder in his body, he will be able to swim freely in the water like a small fish. What an amazing thing that would be!

Now there are many special lights for students on the market, and ** is not low, do we need to buy them? Can't fluorescent and fluorescent lamps be used? Faced with these problems, we learned the following:

There are many types of lamps and lanterns, which can be divided into incandescent lamps and cold light lamps from the perspective of daily use. The working principle of incandescent lamps is relatively simple, which is to heat the filament to an extremely high temperature and enter an incandescent state, so as to convert electrical energy into light energy and emit visible light. The main feature of this type of luminaire is that the temperature of the luminaire itself is very high, and the "color temperature" of the light emitting is low.

What is "color temperature"? Let's give you a simple example: suppose there is a piece of coal, burn it, then it will emit different light at different combustion temperatures, at lower temperatures, the color is reddish, and with the increase of temperature, the color changes to blue, which is the corresponding coloring temperature.

Color temperature only causes the color change of the object, for example, when choosing clothes in the shopping mall, experienced customers always take the window to see the color, and do not judge under the lights of the shopping mall, which is the reason, it can be seen that incandescent lamps will not affect people's eyesight.

The luminous principle of cold light lamps is more complex, and the bulb or tube of this type of lamp always has a phosphor inner coating. It also has a filament, but it does not work only by a red-hot filament, and the temperature of the lamp itself is not high, but the color temperature is often high, giving people the feeling of blue light, but it still has nothing to do with human eyesight.

From the above, we can know that as long as there is a correct and hygienic eye habit and sufficient illumination, it is enough to prevent myopia. If you don't have the right eye habits, even if you only read and work in the sun, you will also be short-sighted.

In recent years, many eye protection lamps on the market do not have much scientific and technological content of their own, nor do they have sufficient theoretical support, but they use people's psychological factors (such as fear of disease, fashion, love of children, etc.) to make profits. Manufacturers use excessively intimidating propaganda to confuse people's ability to judge goods. In fact, as long as we understand some corresponding principles, it is not difficult to use the scientific knowledge we know to make correct judgments.