What kind of light does sunlight consist of?

Open classification: optics, light source, nuclear reaction, spectrum, visible light.

Sunlight is the light emitted by nuclear reaction "burning" on the sun. It traveled a long distance to the earth and reached the ground after being filtered by the atmosphere. Its energy distribution in the visible spectrum is uniform, so it is white light.

The light emitted by various light sources is different in length, intensity and proportion, forming different colors of light, which is called light source color.

The color of light source is an important factor that affects and determines the color of objects. 1666, isaac newton, a British scientist, made the first experiment to separate the solar beam with a prism, which proved that the white light of the sun is composed of various colors.

Sunlight is the most important natural light source. It shines on the earth and makes the whole world colorful. When light changes with time and weather, it will directly affect the color of objects.

There is no other light source except sunlight, such as the light used in our daily life. It is an artificial light source, which is much weaker than sunlight and contains different proportions of visible light. Generally, the light emitted by incandescent lamps is often red and yellow, while the light emitted by fluorescent lamps is blue.

"The sun is the mother of the earth", and it is the sunlight that makes the earth full of vitality. The wind blows wildly, the river flows, flowers bloom and fruits ripen, and life is endless. The sun is an inexhaustible source of energy. At present, people are trying their best to make use of solar energy.

In the 1970s, the number of meteorological observation stations increased, and it was found that the eastern Sahara desert had the most sunshine, with an average annual sunshine hours of 4,300 hours. In other words, you can see the bright sunshine for about 1 1 hour for 45 minutes every day.

Why is there so much sunshine in the East Sahara Desert? Because this is the driest place in the world, there is no cloud that can block the sun; Coupled with the low latitude and long sunshine time, it has become the place with the most sunshine in the world.

Sunlight consists of ultraviolet rays, infrared rays and visible light.

visible light

Open classification: physics, optics

Refers to electromagnetic waves that can cause vision. The wavelength range of visible light is between 0.77 and 0.39 micron. Electromagnetic waves with different wavelengths make human eyes feel different colors. 0.77 ~ 0.622 micron, feeling reddish; 0.622 ~ 0.597 micron, orange; 0.597 ~ 0.577 micron, yellow; 0.577 ~ 0.492 micron, green; 0.492 ~ 0.455 micron, indigo blue; 0.455 ~ 0.39 micron, purple.

Visible light is the part of the electromagnetic spectrum that can be perceived by human eyes, and the visible spectrum has no precise range; Ordinary people's eyes can perceive electromagnetic waves with a wavelength between 400 and 700 nanometers, but some people can perceive electromagnetic waves with a wavelength between 380 and 780 nanometers. Human eyes with normal vision are most sensitive to electromagnetic waves with a wavelength of about 555 nm, which is in the green region of the spectrum.

The range of light visible to human eyes is influenced by the atmosphere. Except visible light and a few other bands, such as radio communication, the atmosphere is opaque to most electromagnetic radiation. Many other creatures can see different light wave ranges from humans. For example, some insects, including bees, can see ultraviolet waves, which is very helpful for finding nectar.

1666, the British scientist Newton was the first to reveal the secrets of chromaticity and color of light. He used experiments to prove that sunlight is a mixture of various colors and found that the color of light depends on the wavelength of light. The following figure lists the colors of light with different wavelengths in the visible range.

Colors of light with different wavelengths (see figure)

In order to study the chromaticity properties of light conveniently, the visible spectrum is surrounded by a ring and divided into nine regions (see figure), which are called color rings. The number on the color ring indicates the wavelength of the corresponding color light, and the unit is nanometer (nm). The colors of any two opposite sectors on the color circle are called complementary colors. For example, the complementary color of blue (435-480 nm) is yellow (580-595 nm). It is found that colored light also has the following characteristics: (l) White light is composed of complementary colors mixed in a certain proportion. For example, when blue light and yellow light are mixed, white light is obtained. Similarly, the mixture of green light and orange light is also white light; (2) Any color on the color ring can be reproduced by two monochromatic lights on its adjacent side, or even by mixing two monochromatic lights from the next nearest neighbor. Such as yellow light and red light, to obtain orange light. Typically, red light and green light are mixed into yellow light; (3) If three independent monochromatic lights are selected on the color ring. Can be mixed in different proportions into various colors that may appear in daily life. These three kinds of monochromatic light are called trichromatic light. The three primary colors in optics are red, green and blue. It should be noted here that the three primary colors of pigment are red, yellow and blue. However, the choice of three primary colors is completely arbitrary; (4) When sunlight irradiates an object, light with a certain wavelength is absorbed by the object, and the color displayed by the object (reflected light) is the complementary color of colored light. If the sun shines on an object, if the object absorbs purple light with a wavelength of 400 ~ 435 ntn, the object appears yellow-green. It should be noted here that some people say that the color of an object is that it absorbs light of other colors and reflects light of this color. This statement is wrong. For example, yellow-green leaves actually only absorb purple light with a wavelength of 400 ~ 435 μm, and the yellow-green color is a mixed effect of other reflected colors, not just yellow-green light.