Natural light sources: examples. Which sources of light are natural?

In ancient times, mankind thought that we can see through the rays-tentacles, which come out of our eyes, as if trying to touch the objects. It seems ridiculous and funny. But in fact, what is light? Where does it come from? There are natural light sources and artificial ones. Modern ideas say that light is electromagnetic waves or a stream of photons. In fact, light is radiation, but that part of it that can be perceived by the eye. That is why it is called visible radiation. When the light propagates, its wave qualities are revealed. About which we will talk below.

Shine

What is it? Let's just say it's an electromagnetic wave. It is perceived by the eyes of a person. True, there are limits of perception - from 380 to 780 nm. At lower rates, there is a flux of ultraviolet that a person can not see, but feels. On the skin it appears as a tan. There is also infrared radiation, which only certain living organisms can see, and people perceive it as heat.

Light is of different colors. If you remember the rainbow, she is the owner of seven colors. The purple color present in it is formed by a beam of 380 nm wavelength, red light - 625, and green - 500, more than violet, but less than red. Many artificial light sources emit white waves. White light occurs when all other primary colors are mixed - red, orange, yellow, green, blue, blue and violet.

Properties

Thanks to experiments, it was possible to establish that light is of an electromagnetic nature. Simply put, light is electromagnetic radiation that can be seen.

Light can boast of having the ability to pass through transparent substances and bodies. Thanks to this, sunlight through the atmosphere easily penetrates to the ground. But at the same time it is refracted. When there is an opaque body or object in the path of light, the light is reflected from them. Thus we take the reflected color with the eye and see not only the color, but also the shape.

A certain part of the light is absorbed by objects, and they heat up. Light objects do not heat up as much as dark ones, since they absorb more light, and reflect less. That's why they look dark. The lion's part of the information that surrounds us, comes through sight. Thanks to him we analyze everything. Good eyesight and a high level of performance are very related to lighting.

Sources

The bodies from which light emanates are also the sources of light. There are natural and artificial light sources. The most popular and vital natural source of light is the Sun, namely solar radiation is the radiant flux of a star that reaches the surface of our planet in the form of direct and scattered light. In natural light, and to be more precise in its spectrum, there are ultraviolet rays, which are simply necessary for a person. Diffusion is a characteristic feature of natural light. This is favorable for eyesight. After we have dealt with many concepts, we can begin to explain what it is - artificial and natural light sources.

Artificial sources

Until the end of the 19th century, the only artificial light source was fire, in all its interpretations. Later, the rapid development of electric light sources was actively launched. For almost 130 years of their existence, the fire was almost completely superseded - kerosene lamps and candles appeared. They are still used when an accident occurs at the station, when lighting suddenly disappears, for a romantic evening, to create an appropriate environment. In the hikes, when the lanterns are exhausted, a kerosene lamp is used. For more extensive lighting, you can build a fire.

Is the bonfire an artificial or natural light source? It is necessary to understand. The flame of burning dry branches, as well as the flame of a candle, a gas burner and so on are artificial sources. I would like to note one feature. Artificial light sources can be controlled by people.

We will argue as follows: in principle, a fire burns independently, giving also heat. Near him you can bask, see in the dark time of friends sitting opposite and singing to the guitar. Like a bonfire is a natural light source. He gives his unconfined light, like the moon. But then the fire begins to go out, it becomes necessary to throw firewood. The more wood, the more the flame. So, they can be controlled. Moreover, originally the fire was created by the tourists themselves. And artificial sources are those created by man. Hence the conclusion: a fire is an artificial light source after all.

Artificial are also technical devices, the most diverse structure. These are incandescent lamps, floodlights, electric lamps and so on. There are bodies that can not radiate independently, but emit reflected light, for example, the Moon.

In more detail, consider which sources of light are natural.

Natural sources

All objects from which the natural light flows, should be attributed to natural sources. They are natural sources of light. It does not matter what the emission of waves is, as the main or secondary property. Natural light sources play a huge role in the life of all living organisms. Natural sources in nature are not controlled by humans:

• Sunlight.
• Fire, a natural light source.
• Starlight.
• Glow of various animals and plant organisms.

And this is not the whole list. You can also list the natural light sources. Examples: The sun scorching the July day, the stars that can be seen at night and stack them in freaky constellations, lightning bursting loose clouds, a comet with a luxurious tail or a polar light shining and admiring. Natural light can be considered glittering in the grass, like small grains of gold, insects and some species of fish, importantly floating almost on the seabed.

Interstellar gas

A depleted gas medium fills the space between the stars. The gas is transparent. The main part of the interstellar gas is observed closer to the plane of the Galaxy. This layer has a thickness of many hundreds of parsecs. The chemical composition is similar to most stars - hydrogen, helium and a few heavy particles. The gas is in the atomic, molecular and ionized form, everything depends on the density and temperature. The gas absorbs ultraviolet rays, and they in return give it the available energy. Ultraviolet radiation emanating from hot stars begins to heat the gas. Then the gas itself starts to emit light. Man observes it as a bright nebula.

Bioluminescence

A cunning word means the ability of living organisms to glow. This skill is achieved independently or with the help of symbionts. The Greek word "bios" means life. And the Latin "lumen" is light. Such talent as the creation of light does not belong to everyone. For this, special luminous organs and the possession of a more developed organism are needed. For example, in photophores of fish, in special organoids in unicellular eukaryotes, in the cytoplasm of bacteria. Let us recall the fireflies and some aquatic organisms that inhabit the ocean floor (deep-sea cuttlefish, radiolaria). Bioluminescence is a product of chemical processes, energy that is released, and begins to stand out in the form of light. In other words, this is a special kind of chemiluminescence.

Radioluminescence

This process is caused by the influence of ionizing radiation. Such chemical compounds that emit gamma and X-rays, alpha, beta particles, are used for the appearance of a radio-luminescent layer in certain substances. For example, dyes, which consist of a mixture of zinc sulphide and a source of ionizing radiation, emit light for a long period of time. This period is measured in years and even decades. Such substances have found wide application in special paints. They covered the dials of watches, instruments.

Spread of light

Light does not have the ability to skirt the obstacles that it encounters in its path. It spreads rectilinearly. And nothing else. Therefore, for a thing that does not have transparent properties, a shadow is formed. The shadow is not always black. Since there are scattered and reflected rays of light that come from other objects. Artists know this especially well.

The rays of light can not pass through the dark barrier. For example, if the Moon is between the Sun and the Earth, hence the solar eclipses.

Sources of light. "Hot" and "cold"

Consider natural light sources. Examples of warm sources are the Sun. It is not only the main source of light, but also of heat. Therefore, in the understanding of humanity, light means heat. The hot lava, which rapidly tends down the slope of the volcano, also releases huge amounts of heat, but the light is somewhat less.

Everyone met the "cold" light in their lives. This is a polar glow, fireflies, and putrefactors. But the bodies of the possessors of such light do not heat up.

Point light source

When studying light phenomena, the concept of a "point source of light" appeared. It is not a discovery that all light sources have their own size. The natural source of light is the star. The sun is a yellow dwarf. There are stars much larger, but people perceive them as point sources of light, because they are at a tremendous distance from our planet.

In conclusion, I would like to note still natural sources of light in our mortal existence - this is joy and happiness! Let them never leave you and light your life path.