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1 hertz [Hz] = 1 cycles per second [cycles / s]

Initial value

Converted value

hertz exahertz petahertz terahertz gigahertz megahertz kilohertz hectohertz decahertz decigertz santigertz millihertz microhertz nanohertz picohertz femtohertz attohertz cycles per second wavelength in exameters wavelength in petameters wavelength in terameters wavelength in megameters wavelength in kilometers in decameters wavelength in meters wavelength in decimeters wavelength in centimeters wavelength in millimeters wavelength in micrometers Compton wavelength of an electron Compton wavelength of a proton Compton wavelength of a neutron revolutions per second revolutions per minute revolutions per hour revolutions per day

More about frequency and wavelength

General information

Frequency

Frequency is a quantity that measures how often a particular periodic process repeats. In physics, frequency is used to describe the properties of wave processes. Wave frequency - the number of complete cycles of the wave process per unit of time. The SI unit of frequency is hertz (Hz). One hertz is equal to one oscillation per second.

Wavelength

There are many different types waves in nature, from wind-induced sea waves to electromagnetic waves. The properties of electromagnetic waves depend on the wavelength. Such waves are divided into several types:

• Gamma rays with a wavelength of up to 0.01 nanometer (nm).
• X-rays with a wavelength of 0.01 nm to 10 nm.
• Waves ultraviolet which have a length of 10 to 380 nm. They are not visible to the human eye.
• Light in visible part of the spectrum with a wavelength of 380-700 nm.
• Invisible to humans infrared radiation with a wavelength from 700 nm to 1 millimeter.
• Infrared waves are followed by microwave, with a wavelength from 1 millimeter to 1 meter.
• The longest - radio waves... Their length starts from 1 meter.

This article is about electromagnetic radiation, and especially light. In it, we will discuss how wavelength and frequency affect light, including the visible spectrum, ultraviolet and infrared radiation.

Electromagnetic radiation

Electromagnetic radiation is energy, the properties of which are simultaneously similar to those of waves and particles. This feature is called wave-particle duality. Electromagnetic waves consist of a magnetic wave and an electrical wave perpendicular to it.

The energy of electromagnetic radiation is the result of the movement of particles called photons. The higher the frequency of radiation, the more active they are, and the more harm they can bring to the cells and tissues of living organisms. This is because the higher the frequency of the radiation, the more energy they carry. Great energy allows them to change the molecular structure of the substances on which they act. That is why ultraviolet, X-ray and gamma radiation are so harmful to animals and plants. A huge part of this radiation is in space. It is also present on Earth, despite the fact that the ozone layer of the atmosphere around the Earth blocks most of it.

Electromagnetic radiation and atmosphere

The atmosphere of the earth allows only electromagnetic radiation with a certain frequency... Most of gamma rays, X-rays, ultraviolet light, some infrared radiation, and long radio waves are blocked by the Earth's atmosphere. The atmosphere absorbs them and does not let them go further. Part of the electromagnetic waves, in particular, radiation in the short-wave range, is reflected from the ionosphere. All other radiation hits the surface of the Earth. In the upper atmospheric layers, that is, farther from the surface of the Earth, there is more radiation than in the lower layers. Therefore, the higher, the more dangerous it is for living organisms to be there without protective suits.

The atmosphere transmits small amounts of ultraviolet light to the Earth and is harmful to the skin. It is because of ultraviolet rays that people get sunburn and can even get skin cancer. On the other hand, some rays transmitted by the atmosphere are beneficial. For example, infrared rays that hit the Earth's surface are used in astronomy - infrared telescopes track infrared rays emitted by astronomical objects. The higher from the surface of the Earth, the more infrared radiation, therefore telescopes are often installed on mountain tops and other elevations. Sometimes they are sent into space to improve the visibility of infrared rays.

Relationship between frequency and wavelength

Frequency and wavelength are inversely proportional to each other. This means that as the wavelength increases, the frequency decreases and vice versa. It is easy to imagine: if the frequency of oscillations of the wave process is high, then the time between oscillations is much shorter than for waves, the oscillation frequency of which is less. If you imagine a wave on a chart, then the distance between its peaks will be the smaller, the more oscillations it makes over a certain period of time.

To determine the speed of propagation of a wave in a medium, it is necessary to multiply the frequency of the wave by its length. Electromagnetic waves in a vacuum always propagate at the same speed. This speed is known as the speed of light. It is equal to 299 & nbsp792 & nbsp458 meters per second.

Light

Visible light is electromagnetic waves of frequency and length that determine its color.

Wavelength and color

The shortest wavelength of visible light is 380 nanometers. It is purple, followed by blue and cyan, then green, yellow, orange, and finally red. White light consists of all colors at once, that is, white objects reflect all colors. This can be seen with a prism. The light entering it is refracted and lined up in a strip of colors in the same sequence as in a rainbow. This sequence is from the colors with the shortest wavelength to the longest. The dependence of the speed of propagation of light in a substance on the wavelength is called dispersion.

A rainbow is formed in a similar way. Water droplets scattered in the atmosphere after rain behave like a prism and refract every wave. The colors of the rainbow are so important that in many languages ​​there are mnemonics, that is, a technique for memorizing the colors of the rainbow, so simple that even children can remember them. Many Russian speaking children know that "Every hunter wants to know where the pheasant is sitting." Some people come up with their own mnemonics, and this is a particularly useful exercise for children, because when they come up with their own method of remembering the colors of the rainbow, they will remember them faster.

The light to which the human eye is most sensitive is green, with a wavelength of 555 nm in light environments and 505 nm in twilight and darkness. Not all animals can distinguish colors. In cats, for example, color vision is not developed. On the other hand, some animals see colors much better than humans. For example, some species see ultraviolet and infrared light.

Light reflection

The color of an object is determined by the wavelength of light reflected from its surface. White objects reflect all waves of the visible spectrum, while black ones, on the contrary, absorb all waves and reflect nothing.

One of the natural materials with a high dispersion coefficient is diamond. Properly cut diamonds reflect light from both the outer and inner edges, refracting it, just like a prism. In this case, it is important that most of this light is reflected upwards towards the eye, and not, for example, downwards, into the frame, where it is not visible. Thanks to their high dispersion, diamonds shine very beautifully in the sun and under artificial light. Glass cut like a diamond also shines, but not as much. This is because, due to their chemical composition, diamonds reflect light much better than glass. The angles used when cutting diamonds are extremely important because corners that are too sharp or too obtuse either prevent light from reflecting off the interior walls or reflect light into the setting, as shown in the illustration.

Spectroscopy

Spectral analysis or spectroscopy is sometimes used to determine the chemical composition of a substance. This method is especially good if the chemical analysis of a substance cannot be carried out by working with it directly, for example, when determining the chemical composition of stars. Knowing what kind of electromagnetic radiation a body absorbs, you can determine what it consists of. Absorption spectroscopy, one of the branches of spectroscopy, determines which radiation is absorbed by the body. Such analysis can be done at a distance, therefore it is often used in astronomy, as well as in working with poisonous and dangerous substances.

Determination of the presence of electromagnetic radiation

Visible light, like all electromagnetic radiation, is energy. The more energy is emitted, the easier it is to measure this radiation. The amount of radiated energy decreases as the wavelength increases. Vision is possible precisely because humans and animals recognize this energy and sense the difference between radiation of different wavelengths. Electromagnetic radiation of different lengths is perceived by the eye as different colors. According to this principle, not only the eyes of animals and people work, but also technologies created by people for processing electromagnetic radiation.

Visible light

People and animals see a wide range of electromagnetic radiation. Most people and animals, for example, react to visible light and some animals are also exposed to ultraviolet and infrared rays. The ability to distinguish colors - not in all animals - some only see the difference between light and dark surfaces. Our brain determines the color as follows: photons of electromagnetic radiation enter the eye on the retina and, passing through it, excite the cones, photoreceptors of the eye. As a result, a signal is transmitted through the nervous system to the brain. In addition to cones, there are other photoreceptors, rods, in the eyes, but they are not able to distinguish colors. Their purpose is to determine the brightness and intensity of light.

There are usually several types of cones in the eye. There are three types in humans, each of which absorbs photons of light within specific wavelengths. When they are absorbed, a chemical reaction occurs, as a result of which nerve impulses with information about the wavelength enter the brain. These signals are processed by the visual cortex. This is the part of the brain responsible for the perception of sound. Each type of cone is responsible only for waves with a certain length, so to get a complete picture of the color, the information received from all the cones is added together.

Some animals have even more types of cones than humans. So, for example, in some species of fish and birds, there are from four to five types. Interestingly, some animal females have more types of cones than males. Some birds, such as seagulls that catch their prey in or on the water, have yellow or red oil droplets inside the cones that act as a filter. This helps them see more colors. The eyes of reptiles are arranged in a similar way.

Infrared light

In snakes, unlike humans, not only visual receptors, but also sensory organs that respond to infrared radiation... They absorb the energy of infrared rays, that is, they react to heat. Some devices, such as night vision goggles, also react to the heat generated by the infrared emitter. Such devices are used by the military, as well as to ensure the safety and security of premises and territory. Animals that see infrared light, and devices that can recognize it, see not only objects that are in their field of view at the moment, but also traces of objects, animals, or people that were there before, if too a lot of time. For example, snakes can be seen if rodents have dug a hole in the ground, and police who use night vision devices can see if traces of a crime, such as money, drugs, or something else, have recently been hidden in the ground. Devices for recording infrared radiation are used in telescopes, as well as for checking containers and cameras for leaks. With their help, the place of heat leakage is clearly visible. In medicine, infrared images are used for diagnostics. In art history - to determine what is depicted under the top coat of paint. Night vision devices are used to guard premises.

Ultraviolet light

Some fish see ultraviolet light... Their eyes contain pigment that is sensitive to ultraviolet rays. Fish skin contains areas that reflect ultraviolet light that are invisible to humans and other animals - which is often used in the animal kingdom to mark the sex of animals, as well as for social purposes. Some birds also see ultraviolet light. This skill is especially important during the mating season when the birds are looking for potential mates. The surfaces of some plants also reflect UV light well, and the ability to see it helps in finding food. In addition to fish and birds, some reptiles, such as turtles, lizards, and green iguanas (pictured), see ultraviolet light.

The human eye, like the eyes of animals, absorbs ultraviolet light, but cannot process it. In humans, it destroys cells in the eye, especially in the cornea and lens. This, in turn, causes various diseases and even blindness. Despite the fact that ultraviolet light is harmful to vision, a small amount of it is necessary for humans and animals to produce vitamin D. Ultraviolet radiation, like infrared, is used in many industries, for example, in medicine for disinfection, in astronomy for observing stars and other objects. and in chemistry for the solidification of liquid substances, as well as for visualization, that is, to create diagrams of the distribution of substances in a certain space. With the help of ultraviolet light, counterfeit banknotes and passes are detected if signs are to be printed on them with special ink recognizable using ultraviolet light. In the case of counterfeiting documents, an ultraviolet lamp does not always help, as criminals sometimes use the real document and replace it with a photograph or other information, so that the markings for the ultraviolet lamps remain. There are many other uses for ultraviolet radiation as well.

Color blindness

Some people are unable to distinguish colors due to visual defects. This problem is called color blindness or color blindness, after the person who first described this feature of vision. Sometimes people can't see only colors at a certain wavelength, and sometimes they can't see colors at all. Often the cause is underdeveloped or damaged photoreceptors, but in some cases the problem lies in damage to the pathway of the nervous system, for example, in the visual cortex of the brain, where color information is processed. In many cases, this condition creates inconveniences and problems for people and animals, but sometimes the inability to distinguish colors, on the contrary, is an advantage. This is confirmed by the fact that, despite the long years of evolution, color vision is not developed in many animals. People and animals that are color blind may, for example, see camouflage of other animals well.

Despite the benefits of color blindness, in society it is considered a problem, and for people with color blindness, the road to some professions is closed. Usually they cannot get full rights to fly the aircraft without restrictions. In many countries, driving licenses for these people also have restrictions, and in some cases they cannot get a license at all. Therefore, they cannot always find a job where they need to drive a car, an airplane, and other vehicles. They also find it difficult to find a job where the ability to identify and use colors has great importance... For example, they find it difficult to become designers, or work in an environment where color is used as a signal (for example, about danger).

Work is underway to create more favorable conditions for people with color blindness. For example, there are tables in which colors correspond to signs, and in some countries these signs are used in offices and public places along with color. Some designers do not use or limit the use of color to convey important information in their works. Instead of, or along with color, they use brightness, text, and other ways to highlight information so that even people who cannot distinguish colors can fully receive the information conveyed by the designer. In most cases, people with color blindness do not distinguish between red and green, so designers sometimes replace the combination “red = danger, green = okay” with red and blue. Majority operating systems also allow you to customize colors so that people with color blindness can see everything.

Color in machine vision

Machine vision in color is a fast-growing branch of artificial intelligence. Until recently, most of the work in this area took place with monochrome images, but now more and more scientific laboratories are working with color. Some algorithms for working with monochrome images are also used for processing color images.

Application

Machine vision is used in a number of industries, such as controlling robots, self-driving cars, and unmanned aerial vehicles. It is useful in the field of security, for example, for identifying people and objects from photographs, for searching databases, for tracking the movement of objects, depending on their color, and so on. Determining the location of moving objects allows the computer to determine the direction of a person's gaze or track the movement of cars, people, hands, and other objects.

In order to correctly identify unfamiliar objects, it is important to know about their shape and other properties, but color information is not so important. When working with familiar objects, on the contrary, color helps to recognize them faster. Working with color is also convenient because color information can be obtained even from low-resolution images. To recognize the shape of an object, as opposed to color, requires a high resolution... Working with color instead of subject shape reduces processing time and uses less computer resources... Color helps to recognize objects of the same shape, and can also be used as a signal or sign (for example, red is a signal of danger). In this case, you do not need to recognize the shape of this sign, or the text written on it. There are many interesting examples of the use of color vision on the YouTube website.

Processing color information

Photos processed by the computer are either uploaded by users or taken by the built-in camera. The process of digital photography and video shooting is well mastered, but the processing of these images, especially in color, is associated with many difficulties, many of which have not yet been resolved. This is due to the fact that color vision in humans and animals is very complex, and it is not easy to create computer vision similar to human vision. Vision, like hearing, is based on adaptation to the environment. The perception of sound depends not only on the frequency, sound pressure and duration of the sound, but also on the presence or absence of other sounds in the environment. So it is with vision - the perception of color depends not only on frequency and wavelength, but also on the characteristics of the environment. For example, the colors of the surrounding objects affect our perception of color.

From an evolutionary perspective, such adaptations are necessary to help us get used to our environment and to stop paying attention to insignificant elements, but to direct our full attention to what is changing in the environment. This is necessary in order to make it easier to spot predators and find food. Sometimes optical illusions occur due to this adaptation. For example, depending on the color of the surrounding objects, we perceive the color of two bodies differently, even when they reflect light with the same wavelength. The illustration shows an example of such an optical illusion. The brown square at the top of the image (second row, second column) appears lighter than the brown square at the bottom of the image (fifth row, second column). In fact, their colors are the same. Even knowing this, we still perceive them as different colors. Since our perception of color is so complex, it is difficult for programmers to describe all these nuances in algorithms for machine vision. Despite these difficulties, we have already achieved a lot in this area.

Unit Converter articles were edited and illustrated by Anatoly Zolotkov

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1 megahertz [MHz] = 1,000,000 hertz [Hz]

Initial value

Converted value

hertz exahertz petahertz terahertz gigahertz megahertz kilohertz hectohertz decahertz decigertz santigertz millihertz microhertz nanohertz picohertz femtohertz attohertz cycles per second wavelength in exameters wavelength in petameters wavelength in terameters wavelength in megameters wavelength in kilometers in decameters wavelength in meters wavelength in decimeters wavelength in centimeters wavelength in millimeters wavelength in micrometers Compton wavelength of an electron Compton wavelength of a proton Compton wavelength of a neutron revolutions per second revolutions per minute revolutions per hour revolutions per day

More about frequency and wavelength

General information

Frequency

Frequency is a quantity that measures how often a particular periodic process repeats. In physics, frequency is used to describe the properties of wave processes. Wave frequency - the number of complete cycles of the wave process per unit of time. The SI unit of frequency is hertz (Hz). One hertz is equal to one oscillation per second.

Wavelength

There are many different types of waves in nature, from wind-induced sea waves to electromagnetic waves. The properties of electromagnetic waves depend on the wavelength. Such waves are divided into several types:

• Gamma rays with a wavelength of up to 0.01 nanometer (nm).
• X-rays with a wavelength of 0.01 nm to 10 nm.
• Waves ultraviolet which have a length of 10 to 380 nm. They are not visible to the human eye.
• Light in visible part of the spectrum with a wavelength of 380-700 nm.
• Invisible to humans infrared radiation with a wavelength from 700 nm to 1 millimeter.
• Infrared waves are followed by microwave, with a wavelength from 1 millimeter to 1 meter.
• The longest - radio waves... Their length starts from 1 meter.

This article is about electromagnetic radiation, and especially light. In it, we will discuss how wavelength and frequency affect light, including the visible spectrum, ultraviolet and infrared radiation.

Electromagnetic radiation

Electromagnetic radiation is energy, the properties of which are simultaneously similar to those of waves and particles. This feature is called wave-particle duality. Electromagnetic waves consist of a magnetic wave and an electrical wave perpendicular to it.

The energy of electromagnetic radiation is the result of the movement of particles called photons. The higher the frequency of radiation, the more active they are, and the more harm they can bring to the cells and tissues of living organisms. This is because the higher the frequency of the radiation, the more energy they carry. Great energy allows them to change the molecular structure of the substances on which they act. That is why ultraviolet, X-ray and gamma radiation are so harmful to animals and plants. A huge part of this radiation is in space. It is also present on Earth, despite the fact that the ozone layer of the atmosphere around the Earth blocks most of it.

Electromagnetic radiation and atmosphere

The earth's atmosphere only transmits electromagnetic radiation at a specific frequency. Most of gamma rays, X-rays, ultraviolet light, some infrared radiation, and long radio waves are blocked by the Earth's atmosphere. The atmosphere absorbs them and does not let them go further. Part of the electromagnetic waves, in particular, radiation in the short-wave range, is reflected from the ionosphere. All other radiation hits the surface of the Earth. In the upper atmospheric layers, that is, farther from the surface of the Earth, there is more radiation than in the lower layers. Therefore, the higher, the more dangerous it is for living organisms to be there without protective suits.

The atmosphere transmits small amounts of ultraviolet light to the Earth and is harmful to the skin. It is because of ultraviolet rays that people get sunburn and can even get skin cancer. On the other hand, some rays transmitted by the atmosphere are beneficial. For example, infrared rays that hit the Earth's surface are used in astronomy - infrared telescopes track infrared rays emitted by astronomical objects. The higher from the surface of the Earth, the more infrared radiation, therefore telescopes are often installed on mountain tops and other elevations. Sometimes they are sent into space to improve the visibility of infrared rays.

Relationship between frequency and wavelength

Frequency and wavelength are inversely proportional to each other. This means that as the wavelength increases, the frequency decreases and vice versa. It is easy to imagine: if the frequency of oscillations of the wave process is high, then the time between oscillations is much shorter than for waves, the oscillation frequency of which is less. If you imagine a wave on a chart, then the distance between its peaks will be the smaller, the more oscillations it makes over a certain period of time.

To determine the speed of propagation of a wave in a medium, it is necessary to multiply the frequency of the wave by its length. Electromagnetic waves in a vacuum always propagate at the same speed. This speed is known as the speed of light. It is equal to 299 & nbsp792 & nbsp458 meters per second.

Light

Visible light is electromagnetic waves of frequency and length that determine its color.

Wavelength and color

The shortest wavelength of visible light is 380 nanometers. It is purple, followed by blue and cyan, then green, yellow, orange, and finally red. White light consists of all colors at once, that is, white objects reflect all colors. This can be seen with a prism. The light entering it is refracted and lined up in a strip of colors in the same sequence as in a rainbow. This sequence is from the colors with the shortest wavelength to the longest. The dependence of the speed of propagation of light in a substance on the wavelength is called dispersion.

A rainbow is formed in a similar way. Water droplets scattered in the atmosphere after rain behave like a prism and refract every wave. The colors of the rainbow are so important that in many languages ​​there are mnemonics, that is, a technique for memorizing the colors of the rainbow, so simple that even children can remember them. Many Russian speaking children know that "Every hunter wants to know where the pheasant is sitting." Some people come up with their own mnemonics, and this is a particularly useful exercise for children, because when they come up with their own method of remembering the colors of the rainbow, they will remember them faster.

The light to which the human eye is most sensitive is green, with a wavelength of 555 nm in light environments and 505 nm in twilight and darkness. Not all animals can distinguish colors. In cats, for example, color vision is not developed. On the other hand, some animals see colors much better than humans. For example, some species see ultraviolet and infrared light.

Light reflection

The color of an object is determined by the wavelength of light reflected from its surface. White objects reflect all waves of the visible spectrum, while black ones, on the contrary, absorb all waves and reflect nothing.

One of the natural materials with a high dispersion coefficient is diamond. Properly cut diamonds reflect light from both the outer and inner edges, refracting it, just like a prism. In this case, it is important that most of this light is reflected upwards towards the eye, and not, for example, downwards, into the frame, where it is not visible. Thanks to their high dispersion, diamonds shine very beautifully in the sun and under artificial light. Glass cut like a diamond also shines, but not as much. This is because, due to their chemical composition, diamonds reflect light much better than glass. The angles used when cutting diamonds are extremely important because corners that are too sharp or too obtuse either prevent light from reflecting off the interior walls or reflect light into the setting, as shown in the illustration.

Spectroscopy

Spectral analysis or spectroscopy is sometimes used to determine the chemical composition of a substance. This method is especially good if the chemical analysis of a substance cannot be carried out by working with it directly, for example, when determining the chemical composition of stars. Knowing what kind of electromagnetic radiation a body absorbs, you can determine what it consists of. Absorption spectroscopy, one of the branches of spectroscopy, determines which radiation is absorbed by the body. Such analysis can be done at a distance, therefore it is often used in astronomy, as well as in working with poisonous and dangerous substances.

Determination of the presence of electromagnetic radiation

Visible light, like all electromagnetic radiation, is energy. The more energy is emitted, the easier it is to measure this radiation. The amount of radiated energy decreases as the wavelength increases. Vision is possible precisely because humans and animals recognize this energy and sense the difference between radiation of different wavelengths. Electromagnetic radiation of different lengths is perceived by the eye as different colors. According to this principle, not only the eyes of animals and people work, but also technologies created by people for processing electromagnetic radiation.

Visible light

People and animals see a wide range of electromagnetic radiation. Most people and animals, for example, react to visible light and some animals are also exposed to ultraviolet and infrared rays. The ability to distinguish colors - not in all animals - some only see the difference between light and dark surfaces. Our brain determines the color as follows: photons of electromagnetic radiation enter the eye on the retina and, passing through it, excite the cones, photoreceptors of the eye. As a result, a signal is transmitted through the nervous system to the brain. In addition to cones, there are other photoreceptors, rods, in the eyes, but they are not able to distinguish colors. Their purpose is to determine the brightness and intensity of light.

There are usually several types of cones in the eye. There are three types in humans, each of which absorbs photons of light within specific wavelengths. When they are absorbed, a chemical reaction occurs, as a result of which nerve impulses with information about the wavelength enter the brain. These signals are processed by the visual cortex. This is the part of the brain responsible for the perception of sound. Each type of cone is responsible only for waves with a certain length, so to get a complete picture of the color, the information received from all the cones is added together.

Some animals have even more types of cones than humans. So, for example, in some species of fish and birds, there are from four to five types. Interestingly, some animal females have more types of cones than males. Some birds, such as seagulls that catch their prey in or on the water, have yellow or red oil droplets inside the cones that act as a filter. This helps them see more colors. The eyes of reptiles are arranged in a similar way.

Infrared light

In snakes, unlike humans, not only visual receptors, but also sensory organs that respond to infrared radiation... They absorb the energy of infrared rays, that is, they react to heat. Some devices, such as night vision goggles, also react to the heat generated by the infrared emitter. Such devices are used by the military, as well as to ensure the safety and security of premises and territory. Animals that see infrared light, and devices that can recognize it, see not only objects that are in their field of view at the moment, but also traces of objects, animals, or people that were there before, if too a lot of time. For example, snakes can be seen if rodents have dug a hole in the ground, and police who use night vision devices can see if traces of a crime, such as money, drugs, or something else, have recently been hidden in the ground. Devices for recording infrared radiation are used in telescopes, as well as for checking containers and cameras for leaks. With their help, the place of heat leakage is clearly visible. In medicine, infrared images are used for diagnostics. In art history - to determine what is depicted under the top coat of paint. Night vision devices are used to guard premises.

Ultraviolet light

Some fish see ultraviolet light... Their eyes contain pigment that is sensitive to ultraviolet rays. Fish skin contains areas that reflect ultraviolet light that are invisible to humans and other animals - which is often used in the animal kingdom to mark the sex of animals, as well as for social purposes. Some birds also see ultraviolet light. This skill is especially important during the mating season when the birds are looking for potential mates. The surfaces of some plants also reflect UV light well, and the ability to see it helps in finding food. In addition to fish and birds, some reptiles, such as turtles, lizards, and green iguanas (pictured), see ultraviolet light.

The human eye, like the eyes of animals, absorbs ultraviolet light, but cannot process it. In humans, it destroys cells in the eye, especially in the cornea and lens. This, in turn, causes various diseases and even blindness. Despite the fact that ultraviolet light is harmful to vision, a small amount of it is necessary for humans and animals to produce vitamin D. Ultraviolet radiation, like infrared, is used in many industries, for example, in medicine for disinfection, in astronomy for observing stars and other objects. and in chemistry for the solidification of liquid substances, as well as for visualization, that is, to create diagrams of the distribution of substances in a certain space. With the help of ultraviolet light, counterfeit banknotes and passes are detected if signs are to be printed on them with special ink recognizable using ultraviolet light. In the case of counterfeiting documents, an ultraviolet lamp does not always help, as criminals sometimes use the real document and replace it with a photograph or other information, so that the markings for the ultraviolet lamps remain. There are many other uses for ultraviolet radiation as well.

Color blindness

Some people are unable to distinguish colors due to visual defects. This problem is called color blindness or color blindness, after the person who first described this feature of vision. Sometimes people can't see only colors at a certain wavelength, and sometimes they can't see colors at all. Often the cause is underdeveloped or damaged photoreceptors, but in some cases the problem lies in damage to the pathway of the nervous system, for example, in the visual cortex of the brain, where color information is processed. In many cases, this condition creates inconveniences and problems for people and animals, but sometimes the inability to distinguish colors, on the contrary, is an advantage. This is confirmed by the fact that, despite the long years of evolution, color vision is not developed in many animals. People and animals that are color blind may, for example, see camouflage of other animals well.

Despite the benefits of color blindness, in society it is considered a problem, and for people with color blindness, the road to some professions is closed. Usually they cannot get full rights to fly the aircraft without restrictions. In many countries, driving licenses for these people also have restrictions, and in some cases they cannot get a license at all. Therefore, they cannot always find a job where they need to drive a car, an airplane, and other vehicles. They also find it difficult to find a job where the ability to identify and use colors is of great importance. For example, they find it difficult to become designers, or work in an environment where color is used as a signal (for example, about danger).

Work is underway to create more favorable conditions for people with color blindness. For example, there are tables in which colors correspond to signs, and in some countries these signs are used in offices and public places along with color. Some designers do not use or limit the use of color to convey important information in their work. Instead of, or along with color, they use brightness, text, and other ways to highlight information so that even people who cannot distinguish colors can fully receive the information conveyed by the designer. In most cases, people with color blindness do not distinguish between red and green, so designers sometimes replace the combination “red = danger, green = okay” with red and blue. Most operating systems also allow you to customize colors so that people with color blindness can see everything.

Color in machine vision

Machine vision in color is a fast-growing branch of artificial intelligence. Until recently, most of the work in this area took place with monochrome images, but now more and more scientific laboratories are working with color. Some algorithms for working with monochrome images are also used for processing color images.

Application

Machine vision is used in a number of industries, such as controlling robots, self-driving cars, and unmanned aerial vehicles. It is useful in the field of security, for example, for identifying people and objects from photographs, for searching databases, for tracking the movement of objects, depending on their color, and so on. Determining the location of moving objects allows the computer to determine the direction of a person's gaze or track the movement of cars, people, hands, and other objects.

In order to correctly identify unfamiliar objects, it is important to know about their shape and other properties, but color information is not that important. When working with familiar objects, on the contrary, color helps to recognize them faster. Working with color is also convenient because color information can be obtained even from low-resolution images. Recognizing the shape of an object, as opposed to color, requires high resolution. Working with color instead of object shape can reduce image processing time and use less computer resources. Color helps to recognize objects of the same shape, and can also be used as a signal or sign (for example, red is a signal of danger). In this case, you do not need to recognize the shape of this sign, or the text written on it. There are many interesting examples of the use of color vision on the YouTube website.

Processing color information

Photos processed by the computer are either uploaded by users or taken by the built-in camera. The process of digital photography and video shooting is well mastered, but the processing of these images, especially in color, is associated with many difficulties, many of which have not yet been resolved. This is due to the fact that color vision in humans and animals is very complex, and it is not easy to create computer vision similar to human vision. Vision, like hearing, is based on adaptation to the environment. The perception of sound depends not only on the frequency, sound pressure and duration of the sound, but also on the presence or absence of other sounds in the environment. So it is with vision - the perception of color depends not only on frequency and wavelength, but also on the characteristics of the environment. For example, the colors of the surrounding objects affect our perception of color.

From an evolutionary perspective, such adaptations are necessary to help us get used to our environment and to stop paying attention to insignificant elements, but to direct our full attention to what is changing in the environment. This is necessary in order to make it easier to spot predators and find food. Sometimes optical illusions occur due to this adaptation. For example, depending on the color of the surrounding objects, we perceive the color of two bodies differently, even when they reflect light with the same wavelength. The illustration shows an example of such an optical illusion. The brown square at the top of the image (second row, second column) appears lighter than the brown square at the bottom of the image (fifth row, second column). In fact, their colors are the same. Even knowing this, we still perceive them as different colors. Since our perception of color is so complex, it is difficult for programmers to describe all these nuances in algorithms for machine vision. Despite these difficulties, we have already achieved a lot in this area.

Unit Converter articles were edited and illustrated by Anatoly Zolotkov

Do you find it difficult to translate a unit of measurement from one language to another? Colleagues are ready to help you. Post a question to TCTerms and you will receive an answer within a few minutes.

That clock frequency is the most well-known parameter. Therefore, it is necessary to specifically deal with this concept. Also, within the framework of this article, we will discuss understanding the clock speed of multi-core processors, because there are interesting nuances that not everyone knows and takes into account.

For quite a long time, the developers have been betting on increasing the clock frequency, but over time, the "fashion" has changed and most of the developments are spent on creating a more perfect architecture, increasing the cache memory and developing multi-core, but no one forgets about the frequency either.

What is CPU clock speed?

First you need to understand the definition of "clock frequency". The clock speed tells us how much the processor can perform calculations per unit of time. Accordingly, the higher the frequency, the more operations the processor can perform per unit of time. The clock speed of modern processors is generally 1.0-4 GHz. It is determined by multiplying the external or base frequency by a certain factor. For example, Intel processor The Core i7 920 uses a 133 MHz FSB and a multiplier of 20, resulting in a clock speed of 2660 MHz.

The frequency of the processor can be increased at home by overclocking the processor. There are special models of processors from AMD and Intel that are focused on overclocking by the manufacturer itself, for example Black Edition from AMD and the K-series line from Intel.

I want to note that when buying a processor, the frequency should not be a decisive factor in your choice, because only part of the processor's performance depends on it.

Understanding Clock Speed ​​(Multi-Core Processors)

Nowadays, there are no single-core processors left in almost all market segments. Well, it is logical, because the IT industry does not stand still, but is constantly moving forward with leaps and bounds. Therefore, you need to clearly understand how the frequency is calculated for processors that have two or more cores.

Visiting many computer forums, I noticed that there is a common misconception about understanding (calculating) the frequencies of multi-core processors. I will immediately give an example of this incorrect reasoning: “There are 4 nuclear processor with a clock frequency of 3 GHz, so its total clock frequency will be: 4 x 3GHz = 12 GHz, right? ”- No, not like that.

I will try to explain why the total processor frequency cannot be understood as: “the number of cores NS the specified frequency ".

Let me give you an example: “A pedestrian is walking along the road, his speed is 4 km / h. This is analogous to a single core processor on N GHz. But if 4 pedestrians are walking along the road at a speed of 4 km / h, then this is similar to a 4-core processor on N GHz. In the case of pedestrians, we do not believe that their speed will be 4x4 = 16 km / h, we just say: "4 pedestrians are walking at a speed of 4 km / h"... For the same reason, we do not perform any mathematical operations with the frequencies of the processor cores, but simply remember that the 4-core processor is N GHz has four cores, each of which operates at a frequency N GHz ".

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1 megahertz [MHz] = 0.001 gigahertz [GHz]

Initial value

Converted value

hertz exahertz petahertz terahertz gigahertz megahertz kilohertz hectohertz decahertz decigertz santigertz millihertz microhertz nanohertz picohertz femtohertz attohertz cycles per second wavelength in exameters wavelength in petameters wavelength in terameters wavelength in megameters wavelength in kilometers in decameters wavelength in meters wavelength in decimeters wavelength in centimeters wavelength in millimeters wavelength in micrometers Compton wavelength of an electron Compton wavelength of a proton Compton wavelength of a neutron revolutions per second revolutions per minute revolutions per hour revolutions per day

Thermal efficiency and fuel efficiency

More about frequency and wavelength

General information

Frequency

Frequency is a quantity that measures how often a particular periodic process repeats. In physics, frequency is used to describe the properties of wave processes. Wave frequency - the number of complete cycles of the wave process per unit of time. The SI unit of frequency is hertz (Hz). One hertz is equal to one oscillation per second.

Wavelength

There are many different types of waves in nature, from wind-induced sea waves to electromagnetic waves. The properties of electromagnetic waves depend on the wavelength. Such waves are divided into several types:

• Gamma rays with a wavelength of up to 0.01 nanometer (nm).
• X-rays with a wavelength of 0.01 nm to 10 nm.
• Waves ultraviolet which have a length of 10 to 380 nm. They are not visible to the human eye.
• Light in visible part of the spectrum with a wavelength of 380-700 nm.
• Invisible to humans infrared radiation with a wavelength from 700 nm to 1 millimeter.
• Infrared waves are followed by microwave, with a wavelength from 1 millimeter to 1 meter.
• The longest - radio waves... Their length starts from 1 meter.

This article is about electromagnetic radiation, and especially light. In it, we will discuss how wavelength and frequency affect light, including the visible spectrum, ultraviolet and infrared radiation.

Electromagnetic radiation

Electromagnetic radiation is energy, the properties of which are simultaneously similar to those of waves and particles. This feature is called wave-particle duality. Electromagnetic waves consist of a magnetic wave and an electrical wave perpendicular to it.

The energy of electromagnetic radiation is the result of the movement of particles called photons. The higher the frequency of radiation, the more active they are, and the more harm they can bring to the cells and tissues of living organisms. This is because the higher the frequency of the radiation, the more energy they carry. Great energy allows them to change the molecular structure of the substances on which they act. That is why ultraviolet, X-ray and gamma radiation are so harmful to animals and plants. A huge part of this radiation is in space. It is also present on Earth, despite the fact that the ozone layer of the atmosphere around the Earth blocks most of it.

Electromagnetic radiation and atmosphere

The earth's atmosphere only transmits electromagnetic radiation at a specific frequency. Most of gamma rays, X-rays, ultraviolet light, some infrared radiation, and long radio waves are blocked by the Earth's atmosphere. The atmosphere absorbs them and does not let them go further. Part of the electromagnetic waves, in particular, radiation in the short-wave range, is reflected from the ionosphere. All other radiation hits the surface of the Earth. In the upper atmospheric layers, that is, farther from the surface of the Earth, there is more radiation than in the lower layers. Therefore, the higher, the more dangerous it is for living organisms to be there without protective suits.

The atmosphere transmits small amounts of ultraviolet light to the Earth and is harmful to the skin. It is because of ultraviolet rays that people get sunburn and can even get skin cancer. On the other hand, some rays transmitted by the atmosphere are beneficial. For example, infrared rays that hit the Earth's surface are used in astronomy - infrared telescopes track infrared rays emitted by astronomical objects. The higher from the surface of the Earth, the more infrared radiation, therefore telescopes are often installed on mountain tops and other elevations. Sometimes they are sent into space to improve the visibility of infrared rays.

Relationship between frequency and wavelength

Frequency and wavelength are inversely proportional to each other. This means that as the wavelength increases, the frequency decreases and vice versa. It is easy to imagine: if the frequency of oscillations of the wave process is high, then the time between oscillations is much shorter than for waves, the oscillation frequency of which is less. If you imagine a wave on a chart, then the distance between its peaks will be the smaller, the more oscillations it makes over a certain period of time.

To determine the speed of propagation of a wave in a medium, it is necessary to multiply the frequency of the wave by its length. Electromagnetic waves in a vacuum always propagate at the same speed. This speed is known as the speed of light. It is equal to 299 & nbsp792 & nbsp458 meters per second.

Light

Visible light is electromagnetic waves of frequency and length that determine its color.

Wavelength and color

The shortest wavelength of visible light is 380 nanometers. It is purple, followed by blue and cyan, then green, yellow, orange, and finally red. White light consists of all colors at once, that is, white objects reflect all colors. This can be seen with a prism. The light entering it is refracted and lined up in a strip of colors in the same sequence as in a rainbow. This sequence is from the colors with the shortest wavelength to the longest. The dependence of the speed of propagation of light in a substance on the wavelength is called dispersion.

A rainbow is formed in a similar way. Water droplets scattered in the atmosphere after rain behave like a prism and refract every wave. The colors of the rainbow are so important that in many languages ​​there are mnemonics, that is, a technique for memorizing the colors of the rainbow, so simple that even children can remember them. Many Russian speaking children know that "Every hunter wants to know where the pheasant is sitting." Some people come up with their own mnemonics, and this is a particularly useful exercise for children, because when they come up with their own method of remembering the colors of the rainbow, they will remember them faster.

The light to which the human eye is most sensitive is green, with a wavelength of 555 nm in light environments and 505 nm in twilight and darkness. Not all animals can distinguish colors. In cats, for example, color vision is not developed. On the other hand, some animals see colors much better than humans. For example, some species see ultraviolet and infrared light.

Light reflection

The color of an object is determined by the wavelength of light reflected from its surface. White objects reflect all waves of the visible spectrum, while black ones, on the contrary, absorb all waves and reflect nothing.

One of the natural materials with a high dispersion coefficient is diamond. Properly cut diamonds reflect light from both the outer and inner edges, refracting it, just like a prism. In this case, it is important that most of this light is reflected upwards towards the eye, and not, for example, downwards, into the frame, where it is not visible. Thanks to their high dispersion, diamonds shine very beautifully in the sun and under artificial light. Glass cut like a diamond also shines, but not as much. This is because, due to their chemical composition, diamonds reflect light much better than glass. The angles used when cutting diamonds are extremely important because corners that are too sharp or too obtuse either prevent light from reflecting off the interior walls or reflect light into the setting, as shown in the illustration.

Spectroscopy

Spectral analysis or spectroscopy is sometimes used to determine the chemical composition of a substance. This method is especially good if the chemical analysis of a substance cannot be carried out by working with it directly, for example, when determining the chemical composition of stars. Knowing what kind of electromagnetic radiation a body absorbs, you can determine what it consists of. Absorption spectroscopy, one of the branches of spectroscopy, determines which radiation is absorbed by the body. Such analysis can be done at a distance, therefore it is often used in astronomy, as well as in working with poisonous and dangerous substances.

Determination of the presence of electromagnetic radiation

Visible light, like all electromagnetic radiation, is energy. The more energy is emitted, the easier it is to measure this radiation. The amount of radiated energy decreases as the wavelength increases. Vision is possible precisely because humans and animals recognize this energy and sense the difference between radiation of different wavelengths. Electromagnetic radiation of different lengths is perceived by the eye as different colors. According to this principle, not only the eyes of animals and people work, but also technologies created by people for processing electromagnetic radiation.

Visible light

People and animals see a wide range of electromagnetic radiation. Most people and animals, for example, react to visible light and some animals are also exposed to ultraviolet and infrared rays. The ability to distinguish colors - not in all animals - some only see the difference between light and dark surfaces. Our brain determines the color as follows: photons of electromagnetic radiation enter the eye on the retina and, passing through it, excite the cones, photoreceptors of the eye. As a result, a signal is transmitted through the nervous system to the brain. In addition to cones, there are other photoreceptors, rods, in the eyes, but they are not able to distinguish colors. Their purpose is to determine the brightness and intensity of light.

There are usually several types of cones in the eye. There are three types in humans, each of which absorbs photons of light within specific wavelengths. When they are absorbed, a chemical reaction occurs, as a result of which nerve impulses with information about the wavelength enter the brain. These signals are processed by the visual cortex. This is the part of the brain responsible for the perception of sound. Each type of cone is responsible only for waves with a certain length, so to get a complete picture of the color, the information received from all the cones is added together.

Some animals have even more types of cones than humans. So, for example, in some species of fish and birds, there are from four to five types. Interestingly, some animal females have more types of cones than males. Some birds, such as seagulls that catch their prey in or on the water, have yellow or red oil droplets inside the cones that act as a filter. This helps them see more colors. The eyes of reptiles are arranged in a similar way.

Infrared light

In snakes, unlike humans, not only visual receptors, but also sensory organs that respond to infrared radiation... They absorb the energy of infrared rays, that is, they react to heat. Some devices, such as night vision goggles, also react to the heat generated by the infrared emitter. Such devices are used by the military, as well as to ensure the safety and security of premises and territory. Animals that see infrared light, and devices that can recognize it, see not only objects that are in their field of view at the moment, but also traces of objects, animals, or people that were there before, if too a lot of time. For example, snakes can be seen if rodents have dug a hole in the ground, and police who use night vision devices can see if traces of a crime, such as money, drugs, or something else, have recently been hidden in the ground. Devices for recording infrared radiation are used in telescopes, as well as for checking containers and cameras for leaks. With their help, the place of heat leakage is clearly visible. In medicine, infrared images are used for diagnostics. In art history - to determine what is depicted under the top coat of paint. Night vision devices are used to guard premises.

Ultraviolet light

Some fish see ultraviolet light... Their eyes contain pigment that is sensitive to ultraviolet rays. Fish skin contains areas that reflect ultraviolet light that are invisible to humans and other animals - which is often used in the animal kingdom to mark the sex of animals, as well as for social purposes. Some birds also see ultraviolet light. This skill is especially important during the mating season when the birds are looking for potential mates. The surfaces of some plants also reflect UV light well, and the ability to see it helps in finding food. In addition to fish and birds, some reptiles, such as turtles, lizards, and green iguanas (pictured), see ultraviolet light.

The human eye, like the eyes of animals, absorbs ultraviolet light, but cannot process it. In humans, it destroys cells in the eye, especially in the cornea and lens. This, in turn, causes various diseases and even blindness. Despite the fact that ultraviolet light is harmful to vision, a small amount of it is necessary for humans and animals to produce vitamin D. Ultraviolet radiation, like infrared, is used in many industries, for example, in medicine for disinfection, in astronomy for observing stars and other objects. and in chemistry for the solidification of liquid substances, as well as for visualization, that is, to create diagrams of the distribution of substances in a certain space. With the help of ultraviolet light, counterfeit banknotes and passes are detected if signs are to be printed on them with special ink recognizable using ultraviolet light. In the case of counterfeiting documents, an ultraviolet lamp does not always help, as criminals sometimes use the real document and replace it with a photograph or other information, so that the markings for the ultraviolet lamps remain. There are many other uses for ultraviolet radiation as well.

Color blindness

Some people are unable to distinguish colors due to visual defects. This problem is called color blindness or color blindness, after the person who first described this feature of vision. Sometimes people can't see only colors at a certain wavelength, and sometimes they can't see colors at all. Often the cause is underdeveloped or damaged photoreceptors, but in some cases the problem lies in damage to the pathway of the nervous system, for example, in the visual cortex of the brain, where color information is processed. In many cases, this condition creates inconveniences and problems for people and animals, but sometimes the inability to distinguish colors, on the contrary, is an advantage. This is confirmed by the fact that, despite the long years of evolution, color vision is not developed in many animals. People and animals that are color blind may, for example, see camouflage of other animals well.

Despite the benefits of color blindness, in society it is considered a problem, and for people with color blindness, the road to some professions is closed. Usually they cannot get full rights to fly the aircraft without restrictions. In many countries, driving licenses for these people also have restrictions, and in some cases they cannot get a license at all. Therefore, they cannot always find a job where they need to drive a car, an airplane, and other vehicles. They also find it difficult to find a job where the ability to identify and use colors is of great importance. For example, they find it difficult to become designers, or work in an environment where color is used as a signal (for example, about danger).

Work is underway to create more favorable conditions for people with color blindness. For example, there are tables in which colors correspond to signs, and in some countries these signs are used in offices and public places along with color. Some designers do not use or limit the use of color to convey important information in their work. Instead of, or along with color, they use brightness, text, and other ways to highlight information so that even people who cannot distinguish colors can fully receive the information conveyed by the designer. In most cases, people with color blindness do not distinguish between red and green, so designers sometimes replace the combination “red = danger, green = okay” with red and blue. Most operating systems also allow you to customize colors so that people with color blindness can see everything.

Color in machine vision

Machine vision in color is a fast-growing branch of artificial intelligence. Until recently, most of the work in this area took place with monochrome images, but now more and more scientific laboratories are working with color. Some algorithms for working with monochrome images are also used for processing color images.

Application

Machine vision is used in a number of industries, such as controlling robots, self-driving cars, and unmanned aerial vehicles. It is useful in the field of security, for example, for identifying people and objects from photographs, for searching databases, for tracking the movement of objects, depending on their color, and so on. Determining the location of moving objects allows the computer to determine the direction of a person's gaze or track the movement of cars, people, hands, and other objects.

In order to correctly identify unfamiliar objects, it is important to know about their shape and other properties, but color information is not that important. When working with familiar objects, on the contrary, color helps to recognize them faster. Working with color is also convenient because color information can be obtained even from low-resolution images. Recognizing the shape of an object, as opposed to color, requires high resolution. Working with color instead of object shape can reduce image processing time and use less computer resources. Color helps to recognize objects of the same shape, and can also be used as a signal or sign (for example, red is a signal of danger). In this case, you do not need to recognize the shape of this sign, or the text written on it. There are many interesting examples of the use of color vision on the YouTube website.

Processing color information

Photos processed by the computer are either uploaded by users or taken by the built-in camera. The process of digital photography and video shooting is well mastered, but the processing of these images, especially in color, is associated with many difficulties, many of which have not yet been resolved. This is due to the fact that color vision in humans and animals is very complex, and it is not easy to create computer vision similar to human vision. Vision, like hearing, is based on adaptation to the environment. The perception of sound depends not only on the frequency, sound pressure and duration of the sound, but also on the presence or absence of other sounds in the environment. So it is with vision - the perception of color depends not only on frequency and wavelength, but also on the characteristics of the environment. For example, the colors of the surrounding objects affect our perception of color.

From an evolutionary perspective, such adaptations are necessary to help us get used to our environment and to stop paying attention to insignificant elements, but to direct our full attention to what is changing in the environment. This is necessary in order to make it easier to spot predators and find food. Sometimes optical illusions occur due to this adaptation. For example, depending on the color of the surrounding objects, we perceive the color of two bodies differently, even when they reflect light with the same wavelength. The illustration shows an example of such an optical illusion. The brown square at the top of the image (second row, second column) appears lighter than the brown square at the bottom of the image (fifth row, second column). In fact, their colors are the same. Even knowing this, we still perceive them as different colors. Since our perception of color is so complex, it is difficult for programmers to describe all these nuances in algorithms for machine vision. Despite these difficulties, we have already achieved a lot in this area.

Unit Converter articles were edited and illustrated by Anatoly Zolotkov

Do you find it difficult to translate a unit of measurement from one language to another? Colleagues are ready to help you. Post a question to TCTerms and you will receive an answer within a few minutes.

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