A little knowledge about shadow

1. what is a shadow? Light travels in a straight line, and the object in front of the light source blocks the light, and the dark area called shadow is formed where the light can't shine. The reason why we see this area is dark is because the light can't reach behind the blocked objects and can't be reflected into our eyes.

an object can cast shadows of different shapes. When the object is close to the light source, the shadow is larger because the object blocks a lot of light. As the object moves away from the light source, the shadow becomes smaller, because the light blocked by the object decreases. If you rotate an object, you will get different shapes of shadows.

the edge of the shadow may be clear or blurred. When an object is close to the place where the shadow is cast, such as a wall, the edge is clearly visible. When the object is far away from where the shadow is cast, the edge becomes blurred. Sometimes the middle part of the shadow is darker than the edge, the middle part is called umbra, and the lighter area is called penumbra. This shadow will appear when the light source is large. To make all parts of the shadow equally dark, the light source must be small.

outdoor shadows depend on the weather. In clear, cloudless, sunny weather, the shadows are clear and dark. When the weather is cloudy and gray, it is difficult to see the shadow, because the sunlight is scattered by the tiny particles in the cloud and emitted in many directions, which means that the shadow is brighter than usual, so it is not easy to see.

2. Shadow has been very useful to human beings since ancient times. Shadow movement has its fixed pattern, so we can predict the size and position of shadow. When the earth rotates around its axis, everything on the surface of the earth is illuminated by the sun. Mountains, trees and buildings all have shadows, but the position of the shadows changes constantly during the day. As the position of the sun changes, the shadow moves from one side of the object to the other. In the early morning and evening, the sun in the sky is low, and the shadows are long at these times. At noon, when the sun is high in the sky, the shadow is short. The ancients found that the passage of time could be marked by strips, so they invented the sundial to let people know the local time.

3. The color of the shadow depends on the light reflected from the shadow projection, and then the light blocked by the object is deducted. For example, a white wall reflects white light (in fact, white light contains various colors), so it looks white. When part of the white light is covered by an object, the light projected by the object on the wall becomes less, so the shadow part looks darker than the original wall.

If the object selectively blocks the light, the shadow will show different color changes instead of simple brightness changes. As for how to selectively block the light, there are two possibilities. The first is that the object itself is selectively transparent (such as colored glass), so it will change the color of the shadow. Secondly, there is more than one light source, and the colors are different. Objects only cover some light sources. For example, if two light sources, red light and green light, are installed in different positions in the environment, the same object will project two different colors of shadows, red and green, because it is not covered by objects, and it will appear yellow because it is irradiated by both red and green light.

2. Knowledge about shadows

1. What is a shadow? Light travels in a straight line, and the object in front of the light source blocks the light, and the dark area called shadow is formed where the light can't shine.

The reason why we see this area is dark is because the light can't reach behind the blocked objects and can't be reflected into our eyes. An object can cast shadows of different shapes.

when an object is close to a light source, the shadow is large, because the object blocks a lot of light. As the object moves away from the light source, the shadow becomes smaller, because the light blocked by the object decreases.

if you rotate an object, you will get different shapes of shadows. The edge of the shadow may be clear or blurred.

when an object is close to the place where the shadow is cast, such as a wall, the edge is clearly visible. When the object is far away from where the shadow is cast, the edge becomes blurred.

Sometimes the middle part of the shadow is darker than the edge, the middle part is called umbra, and the lighter area is called penumbra. This shadow will appear when the light source is large.

to make all parts of the shadow equally dark, the light source must be small. The shadow outside depends on the weather.

in clear, cloudless and sunny weather, the shadows are clear and dark. When the weather is cloudy and gray, it is difficult to see the shadow, because the sunlight is scattered by the tiny particles in the cloud and emitted in many directions, which means that the shadow is brighter than usual, so it is not easy to see.

2. Shadow has been very useful to human beings since ancient times. Shadow movement has its fixed pattern, so we can predict the size and position of shadow.

when the earth rotates around its axis, everything on the earth's surface is illuminated by the sun. Mountains, trees and buildings all have shadows, but the position of the shadows changes constantly during the day.

as the position of the sun changes, the shadow moves from one side of the object to the other. In the early morning and evening, the sun in the sky is low, and the shadows are long at these times.

at noon, when the sun is high in the sky, the shadow is short. The ancients found that the passage of time could be marked by strips, so they invented the sundial to let people know the local time.

3. The color of the shadow depends on the light reflected from the shadow projection, and then the light blocked by the object is deducted. For example, a white wall reflects white light (in fact, white light contains various colors), so it looks white. When part of the white light is covered by an object, the light projected by the object on the wall becomes less, so the shadow part looks darker than the original wall.

If the object selectively blocks the light, the shadow will show different color changes instead of simple brightness changes. As for how to selectively block the light, there are two possibilities. The first is that the object itself is selectively transparent (such as colored glass), so it will change the color of the shadow.

Secondly, there is more than one light source, and the colors are different. Objects only cover some of the light sources. For example, if two light sources, red light and green light, are installed in different positions in the environment, the same object will cast shadows of two different colors, red and green. As for places that are not covered by objects, they will appear yellow because they are irradiated by both red and green light.

3. Knowledge post about what is "shadow"

Simply put, it is like this: shadow wood is also called cherry (gall) wood, which is literally a sick tree with a tumor.

Shadow refers to the wood where a tree has a nodule or a cherry blossom, which is called shadow. Many kinds of trees can produce shadow wood, such as birch shadow, camphor shadow, nanmu shadow, pear shadow and maple shadow.

shadow trees are mostly born in the roots, and there are fewer cadres. Shadow wood is mostly interlaced, twisted and rotated with fine patterns, with various textures, which are very beautiful, changeable and different styles. Common textures include grape grain walnut pattern, landscape pattern, tiger skin pattern, sesame pattern and raindrop pattern.

The value of shadow wood is firstly its grain and secondly its wood grade. Generally speaking, the order is this: of course, the good grain and color of mahogany hardwood firewood are also important factors of its value. The denser the grain, the more "faces" (birds' eyes), the better. The purpose of shadow wood is generally used for the surface decoration of furniture and utensils, or small utensils, such as box stationery.

mosaic can be done after slicing. Due to the limitation of the size of the material itself, not many large objects are made.

Of course, it can also be made of the natural shape of the huge nodule on the trunk of tree species with fast growth and large DBH, and the appearance is clean, with no or a little artificial modification, such as cherry wood pen holder, painting tube and pen washing. Shadow wood is mostly produced in Southeast Asia, and China is mainly produced in Yunnan, Liaodong, Sichuan and Shanxi.

The above text is a combination of online introduction and personal understanding. Due to my limited experience and level, please correct me if there is anything wrong, and welcome everyone to add! []。

4. Little knowledge about adventure

1: What you must bring when exploring: a lighter! It doesn't matter if you don't bring food. Lighters are necessary. If you meet wild animals at night, you can drive them away. If it's cold, you can light a fire to keep warm. If you catch food, you can use it for cooking (if you get shot, you can sterilize surgical instruments, which is in the movie)

2: Hold your breath and pretend to be dead when you meet a bear! Bears are not interested in dead things!

3: wearing a mask on the back of the head can effectively prevent tigers from attacking, because tigers don't attack people head-on!

4: Most snakes don't take the initiative to attack people, except cobras and rattlesnakes, but usually there are such snakes in tropical rainforests!

5: mung bean soup and soybean milk have detoxification effects. For example, eating toxic food and mung bean soup in the wild can effectively alleviate the toxicity, so you can drink it immediately and save yourself!

6: Wet towel can effectively avoid burning in the hot sun.

7: Aloe, cactus and other plants can also effectively detoxify, and the effect is better than mung bean soup when rescuing people who take poison. If your cat accidentally eats poisonous rats, you can pound them and give them first aid. However, the grass mud is too thick for poisoned animals to drink, so you can drink egg white and cook licorice.

8: Aloe and cactus have good detoxification effects. If the body is bitten by poisonous insects, slices of aloe or cactus can be made and applied to the injured surface.

It is not advisable to enter the dense forest in the morning. There is too much carbon dioxide and insufficient oxygen in the forest in the morning, which is easy to lead to hypoxia, and people with weak constitution are easy to faint.

9: Water is necessary for survival in the wild. If there is no water, you must first find wild fruits that can be used. If there are no wild fruits, the worst way is to borrow plants, put plastic bags on the branches and leaves of green plants, fasten them, and form water droplets on the inside of the bags by photosynthesis and evaporation. Although it is meager, it can save lives.

1: If you get lost, you can refer to the sun and the shadow, which is located in the north of the Tropic of Cancer, and the shadow will never only face south, that is to say, at least in the area north of the Yangtze River: at sunrise, the shadow will go west, and at sunset, you will know the north and south according to the upper north and lower south, left west and right east; The shadow points northwest in the morning, northeast in the afternoon and north at noon.

11: when there is no sun, you can look at plants, and all fabrics have phototropism. The position of the sun can be judged by the orientation of the position, so as to judge the direction according to the above method.

12: You can judge by looking at the moon at night. The moon does not point to the shadow, but it points to the arc. In the middle of the night, you can see that the moon proves to be from the first day to the fifteenth day of the lunar calendar. At this time, the moon gradually becomes round to the other side starting from a static semicircle. This static semicircle points to the west from the first day to the fifteenth day and faces to the east from the sixteenth to the thirtieth.

13: Don't hide under big trees and tall buildings in a thunderstorm.

14: It's best to take off and land with both feet when encountering a grounded wire, and skip this range.

15: You can wear a knife and open the way when encountering thorns.

16: You can take a rope and use it as a tool when climbing.

17: Learn more about animals and plants

5. The main content of Andersen's fairy tale shadow story

This is the original text of the Baidu library Shadow:

Introduction: It was written by Andersen in the coastal city of Naples in southern Italy in the summer of 1846.

the climate there is hot, especially in summer. This "heat" may be the "inspiration" that prompted the author to write this story. But the story itself is "cold", which makes people feel creepy, but it is not impossible in real life.

That scholar, the so-called intellectual, sometimes inevitably falls victim to his own shadow, but he doesn't realize it.

This also shows how sharp Andersen, who is kind, naive and kind, observes life-he is really a great writer!

Later, this fable story was first published in The New Fairy Tale.

++++++++++++++thoughts and feelings:

This fairy tale describes a magical story: a scholar lost his shadow, and then the shadow took on a human form, defrauding the scholar of his social identity, and finally trapping the scholar to death with trickery. The story seems fantastic, but it is thought-provoking, which embodies the author's keen insight and deep thinking on social reality and human nature.

The story of a scholar murdered by his own shadow symbolizes the embarrassing situation that Andersen was misunderstood and distorted by vulgar enthusiasm, and also shows his deeper loneliness.

++++++++++++++++++++

Feelings:

Under the sunshine, shadows always follow the shape, so it seems that. Although the shadow has no independent life, it changes endlessly, and it is inevitable that it will get carried away for a long time, thinking that it is not necessary to be attached to its master, but it can also travel around the world. He said to his master, let's pretend to be friends and go with each other to develop elsewhere. They came to a country, and the king was recruiting a husband for the princess. Shadow boldly applied for the job and was chosen, so he began to hate his master's old and ugly appearance, so he asked the king to put him in prison. On the eve of the wedding, the shadow worried that the master would spoil the game and sent someone to poison the master. then what

The endings of fairy tales are mostly nothing more than: "From then on, Shadow and Princess lived a happy life." However, not this time. The ending should be left to the readers to think for themselves. Answer 1: Since the master is dead, how can the shadow exist alone? The shadow should disappear, making everything like a spring dream, without a trace. Answer 2: The plot of the shadow was exposed and punished appropriately. Answer 3: reflect, are we all making such a shadow? Or, life is the process of the shadow murdering the master?

Shadow symbolizes our fantasies and desires. In order to realize our fantasies and satisfy our desires, we travel around the world, learn the necessary knowledge and skills, and gradually become secular in the process, becoming a typical model welcomed by the society. External roles, status, relationships, and achievements are enough to make people forget themselves and even dislike the inner heart that occasionally questions. The trick of murdering the master is easy to succeed. And the result? The streets are full of shadows. Among the philosophers of the Ming Dynasty, some people claimed that the streets were full of saints. This really needs a special eye, but it is too vague to say the sage. In my opinion, the streets are full of shadows, which may be closer to the truth.

6. Excuse me, who has common sense about reasoning?

People usually start to be stiff within 3 minutes to 2 hours after death, and will be stiff all over after 9 to 12 hours.

it will remain stiff for the next 3 hours, then soften, and recover to its original state after about 7 hours. Usually, this is the case, but if the ambient temperature is higher than 35 degrees, stiffness and softening will accelerate, and it can be recovered in 24 hours.

After strenuous exercise before death, protein is easy to coagulate in the body, and will become stiff faster than usual after death. Suicide is when a gun is pointed at the head, it will leave scorching marks around the bullet hole, and the color of the surrounding skin will also deepen. ※.

The hole where the bullet enters is smaller than the hole where it exits, and there is less blood flow. Generally, only suicide will leave a coke.