What's the use of shadows

Question 1: What's the use of shadows? In ancient times, the length of shadows was used to measure time, such as sundials and watches.

Scientists use the shadows of the peaks on the moon to calculate the height of the peaks.

Shadow play is an art form of performing drama with shadows, which is a traditional opera in China. The figure's outline is made of leather or cardboard. During the performance, the silhouette is illuminated on the curtain with lights, and the actors sing while manipulating behind the scenes.

Use x-ray or CT scanning, etc. It is to determine whether there is a lesion or the severity of the disease through the shadow left by light passing through the human body.

People play hand shadow games and step shadow games, and also use the shadows produced by light and sunlight to entertain people.

People invented movies with the principle of shadow.

Now clever designers have given them another use-shadow effect!

Question 2: What shadows can make a work of art attractive or ugly? In fact, on many occasions, shadows not only bring trouble to people, but also bring benefits to people; Hate and enjoy. If it bothers you, you must be careful with it. Otherwise, it will make you dizzy and even the consequences will be unimaginable. You touched his temper, and he worked for you and did a lot of good things. When you are sitting at a desk reading and writing, if the light comes from the right front or back instead of the left front, the shadow just falls on the paper, forming a strong black-and-white contrast. Over time, eyes will get tired easily. Therefore, it is best to place the desk parallel to the window. The direction of desks in schools should be such that when students face the blackboard, light comes in from the left. The desk lamp should be placed in the front left. When a surgeon is operating on a patient, if he uses ordinary light, the shadow will make the doctor unable to see the blade clearly, and a slight negligence will cause an accident. Therefore, people install shadowless lights in operating rooms. A dozen lamp balls are arranged in a ring shape in the lampshade, each lamp ball is filled with a mirror bulb, and the inner wall of the lower half of the bulb is plated with a layer of aluminum with reflective effect. After turning on the light, the aluminum reflector reflects the light onto the lamp ball, and the light shines from different positions to the same point, driving away the shadow. Although the shadow has brought people a lot of trouble, it has also brought people many wonderful benefits. Walking in the shade of a tree in the hot dog days of summer feels particularly cool. People also consciously create some shadows to serve themselves. In hot weather, farmers can't just hide in the shade to enjoy the cool, and people who go out can't help walking in the sun. In order to avoid the scorching sun, people wear hats and umbrellas, which creates shadows. This is the most common and simplest usage of shadow. Before people invented clocks and calendars, they used shadows to calculate time and distinguish seasons. Behind the Beijing Planetarium, there is a copper watch, which is a horizontal ruler and an upright pole. According to the length of the shadow, you can know what season it is The longest shadow day is the winter solstice, and the shortest is the summer solstice. In the Forbidden City in Beijing, there is an ancient sundial, which uses the direction of the shadow to time. This scale and sundial began to be used in China 2700 years ago. The sundial in India is even more peculiar. It consists of an inclined triangular stone ladder and an arc concave top wall. The stone staircase towering into the sky, up to a dozen stories, its shadow cast on the curved wall, constantly pointing out the time with the movement of the sun. With the development of science and technology, the role of shadow is getting bigger and bigger, and its application scope is getting wider and wider. From daily life to industrial production and transportation, from scientific research to medical and military technology, there are many ways to help people. The doors of some factories are always closed at ordinary times, but when you come near, they automatically get out of the way; As soon as you walked by, it closed itself again. Some machine tools are controlled by photoelectricity and have a high degree of automation. The reason is very simple, that is, a photovoltaic cell is installed. The photoelectric effect principle of photocell makes light and electricity * * *, and turns light waves into electric waves. But this kind of light is not visible light, but invisible light such as infrared ray, ultraviolet ray and X ray. When light shines on the cathode of the photovoltaic cell, the electrons released by the cathode plate are absorbed, thus forming a photocurrent. When a person's shadow blocks the light, the flow immediately stops and plays a controlling role. Using shadow can not only realize automatic production, but also realize safe production and reduce accidents, such as emitting a beam of infrared light next to a high-speed machine and throwing it on a photocell. When the operator reaches the dangerous part, he doesn't have to worry about breaking his hand, because when the hand reaches the dangerous area, the "shadow" can block the infrared light, the photocurrent will be cut off immediately, and the machine will stop as soon as it is conscious.

Question 3: What does the shadow mean? It follows closely and stays together forever.

Question 4: What is the function of Pokemon Shadow? I don't know which version you are talking about, but all the games involve the feature of stepping on the shadow (stepping on the opponent's shadow makes it impossible to escape or exchange)

Question 5: What's the use of shadows? In the words of Buddhism, this question is very profound. Shadow is the god of self-protection-it is called black evil.

In other words, an invisible god who protects himself. Hidden in you, only light can reflect the existence of this god.

Scientifically speaking, the purpose of shadows is to tell you where there is light. Painting is also ok. It is beneficial to enjoy the cool in summer.

Question 6: What are the disadvantages of human shadow? Light is straight and cannot penetrate the human body, so not only people have shadows ~ objects with high density have shadows ~ the principle is simple. If you don't turn on the light, the room will be dark ~ then after turning on the light, some places can't be illuminated because the light is blocked by the human body ~ the places where you can't receive the light are of course dark shadows ~ it's very important ~ all ancestors did. How can you say that it doesn't matter if you use shadows to calculate time? Shadow can also calculate the relative position of the object and light and the shape of the object. Shadow also provides you with the use of stepping on shadow. There are a bunch of them ~ very useful ~ just like Taoism says "useless" As stated in 1, people have shadows because they are opaque and block the progress of light, so hiding is not decided by people. For example, a white wall is white because the environment reflected by the wall gives white light (in fact, white light contains various colors), so it looks white. When a part of the white light is blocked by an object, the light projected by the object on the wall becomes less, so the shadow part looks darker and grayer than the original wall. If today's objects selectively block light, shadows will show different color changes instead of simple brightness changes. There are two possibilities as to how to selectively block the light. The first is that the object itself is selectively transparent (such as colored glass), which will change the color of the shadow. Secondly, there are more than one light source and different colors. The object only covers part of the light source. For example, if two light sources, red and green, are installed in different positions in the environment, the same object will cast two different colors of shadows because it is covered with different light. As for places that are not covered by objects, they will appear yellow because they are irradiated by red light and green light at the same time. Disappearing is very simple, just go to a place without any light source.

Seek adoption

Question 7: What is a shadow? For example, you have a C 30.

If you buy a video package, you can have a 30-level other occupation at will (but you don't have any skills, equipment or data, everything starts at 30).

It is more convenient for rich people to play advanced numbers directly (you don't need points to buy RMB skills)