The White light The term white light is applied to the light in which all the colors that make up the visible spectrum merge, ...
The White light
The term white light is applied to the light in which all the colors that make up the visible spectrum merge, namely: red, orange, yellow, green, blue, indigo, and violet, and white light is usually called visible light , or light for simplicity; It is he who enables a person to see things around him, and from its sources: the sun, stars, and some types of lamps.
White light analysis
Light travels on different frequencies and wavelengths, and each wavelength has a specific speed, which differs when the light travels from one medium to another, for example: the speed of light differs in a vacuum than in air, water, or glass, and when the light passes in a different medium, the Different wavelengths will be refracted at different angles, and the higher the frequency of the wave, the lower its angle of refraction, and vice versa, the refraction depends on the frequency and wavelength of the wave, as well as the material that makes up the medium, and these refractions are at different angles of different frequencies, and this shows the colors of the spectrum. Waveform: red (the largest wavelength), orange, yellow, green, blue, indigo, and violet, and these colors can be obtained by making the light refractive in a glass prism as it passes through it.
The formation of a rainbow on rainstorm days when sunlight penetrates rain clouds is one example of the breakdown of white light into its component colors. This is caused by the refraction of sunlight in raindrops, and this is similar to the refraction of light in a prism.
Complementary colors
Complementary colors are the colors that complement the visible spectrum . That is, by combining them together, white light can be obtained, and these colors are: red, green, and blue. Blue light, for example, constitutes one third of the colors of the visible spectrum, and yellow color constitutes the remaining two thirds. As it is a mixture of red and green, when mixing blue and yellow together; This will produce white light , so blue and yellow can be considered complementary pairs, and other examples of such pairs are green and purple, in addition to red and cyan, so adding each pair of these colors will produce white light.
Colors can also be combined subtractively, that is, each color subtracts another color; Where there are three basic colors used in subtractive analysis, namely: cyan, magenta, and yellow, the sky blue absorbs (subtracts) the red color, while the purple color absorbs the green color, and the yellow absorbs the blue color, for example; When yellow ink was placed on a white paper, the yellow color was not actually added to the paper. Rather, the blue color was absorbed from the white light, and what remained were the green and red colors, then they were reversed on their own, forming yellow together, as well as when mixing yellow and purple on assumption And then exposing them to white light, then the green and blue colors are subtracted from the primary colors of the visible spectrum, so what remains is red, which is the color that will only be visible.
Theories of light
Theories about the nature of light have varied throughout the ages. The ancient Greeks developed the first theories relating to light, and most theories described light as a ray. Any straight line moves from one point to another, and Pythagoras developed a theory according to which vision is a product of light rays that emanate from the human eye and collide with the body, and the philosopher Epicurus refuted this theory, and he considered the exact opposite to be true. His theory stated that it is the body that radiates light, which in turn is transmitted to the eye.
Arab scholars benefited from and developed these theories. They discovered what is called geometric optics, which is the application of geometric foundations in the science of optics specializing in lenses, mirrors, and prisms, and the scientist Ibn al-Haytham was the most famous of the application of engineering optics. He explained the optical components in the human eye, and he also explained the mechanism of vision in a correct way, explaining that it is a process that includes the reflection of light from bodies to human eyes, as well as establishing the laws of refraction of light, and other phenomena related to light, such as the phenomena of the rainbow and the solar eclipse .
The theory that light is a ray cannot explain all the behaviors of light, so the English physicist Thomas Young conducted one of the most famous experiments in history, known as the Young Slit Experiment . This experiment needs a source. For light, a thin card with two holes punched side by side, and a screen, as light is allowed to pass through the hole; It will fall on the card, if the light consists of particles or rays, it will travel in a straight line, and the opaque card will not block it. Of the tapes on the screen, some light-colored and others dark, and from that it reached the wavesThe light traveled through the cracks to the screen, and from here the wave nature of the light was known.
The frequencies of light
After the scientist Maxwell reached the principles of electromagnetic waves, it became possible to explain all the phenomena of light , including the frequency and wavelengths of light, and the wavelength is defined as the distance between two opposite points in successive waves, and the human eye can only see the wavelengths confined between 400-700 nanometers.
Light waves have many frequencies. Where the energy of the wave is directly proportional to its frequency, the higher the frequency of the light, the higher its energy, and vice versa, and the frequency is the number of waves that cross a certain point in a vacuum in a certain period of time, and this period is usually one second, and it is measured in hertz , and it is called the frequency of visible light. color, and is limited to the red light with a frequency 430 trillion Hertz, violet color , which has a frequency 750 trillion Hertz, and there are other types of waves that can not be that man sees, which is outside of the frequencies mentioned, examples include: radio waves , and gamma rays .
Maxwell's description of the principles of electromagnetic waves was sufficient to explain most of the phenomena of light, but at the beginning of the twentieth century, the scientist Max Planck reached to the conclusion that light carries energy in separate quantities, and the scientist Albert Einstein developed Planck's theory, until he concluded that the light contains small particles called photons.
The nature and properties of light
When the light was considered a ray, this explained all the known phenomena of light, which are: reflection, scattering, and refraction.
Reflection and dispersion
In reflection, the rays of light fall on a smooth surface, and are reflected from it, and the angle of reflection is equal to the angle of incidence, and that is when the light falls on the mirror, for example, but if the surface is rough as most surfaces in reality, the angle of reflection will not be equal to the angle of incidence. As for the phenomenon of scattering light rays, when they fall on a rough surface; Where light is reflected in all directions, and this phenomenon is very important. When a person reads from a paper, for example, he will be able to read without any problems, even if the angle of vision of the eye differs from the surface of the paper.
Refraction
Refraction of light occurs when it passes through two different transparent mediums, such as: air and water, and when this occurs, the speed of light will differ, and therefore the incoming ray of light will bend closer or away from the line perpendicular to the surface, and the angle of refraction (the amount of bending) depends on the material For example: Diamonds are shiny; Because the speed of light falling on it is slowed down a lot, when the rays inside are refracted.
Electromagnetic waves
White light waves are part of the electromagnetic spectrum that consists of other waves, such as: radio waves, microwaves, x-rays, gamma rays, infrared rays, and ultraviolet rays; The white light among all of them is the only one that a person can see without resorting to the use of modern technologies.
COMMENTS