Unlike humans, some fish can detect ultraviolet light by absorbing it. Their visual system contains pigment that is sensitive to UV. It is believed that this ability is useful for feeding behaviors and choosing mates, as well as for some other social behaviors. Some birds also detect ultraviolet light, and similar to fish this ability is commonly used in courtship, to distinguish a potential mate. Some plant and animal material reflects UV light well, and these birds use their sensitivity to harvest food.
Several species of lizards, turtles, and rodents also have this ability. Green iguana species pictured are one example. Human eyes can absorb UV as well, but it is not detected. Instead extended exposure damages cells in the retina, the cornea, and the lens, and can cause a range of eye diseases, as well as blindness.
Similar to infrared light, UV is used in a range of areas such as medicine, disinfection, curing materials, chemical imaging, in space observatories, to detect forged currency and sometimes IDs if they are supposed to have marks printed in special UV-detectable ink. The latter does not always work, because some fake IDs are made from real IDs, but the photograph or other information is substituted.
In this case, they would have the special UV-detectable marks, just like the real IDs. Small amounts of UV are also needed by humans and some animals to produce vitamin D. UV radiation is used in other fields as well. Defects in color vision sometimes cause the inability to distinguish between colors.
This could be manifested for a particular wavelength or for all colors. Often this is caused by damaged or underdeveloped photoreceptors, but it could also be caused by the problems higher along the neural pathway to the brain, including brain damage in the visual cortex where the color information is processed. In most cases, this condition provides a disadvantage, but since many animals are color-blind, some scientists believe that this is a trait that developed through natural selection and gave an evolutionary advantage to some species.
For example, color-blind animals and people can see camouflaged animals better than those, who have color vision intact. Despite the potential benefits, color-blindness is viewed as a disadvantage in human society, and some vocational opportunities are limited only to people with normal color vision.
Some countries restrict or completely revoke driving privileges for color-blind people, and it is generally not possible to get a full, restriction-free piloting license for them. Jobs that rely on color information, such as graphic design or professions in which color serves as a warning or as a direction are generally not available to people with color-blindness. To address the problem of color-blindness in people a range of tools is being developed, such as color code tables that use signs to represent colors.
These signs are sometimes used together with color-coding in public places by several countries. Some graphic designers choose not to use color-coding all together or prefer a combination of color and other visual information such as brightness , to ensure that even the color-blind persons benefit from the design.
Some computer interfaces also accommodate for color-blindness under the accessibility settings. Computer vision is a rapidly developing field of artificial intelligence and color recognition is one of its branches.
Until recently a considerable amount of research and development in computer vision has been done without color, but more labs are working on incorporating color vision into their projects. Some algorithms that work with monochrome images are adapted for color images. The applications for computer vision include navigation for robots, self-driving cars and drones, security face recognition, etc , screening image databases, tracking objects based on their color, and many others.
For unfamiliar objects, other characteristics such as shape are more important for successful recognition. However, when interacting with the same objects on multiple occasions, color is very useful for identifying these objects. Colors do not depend on the resolution of the image, as does shape, for example. Therefore processing based on color may allow for faster processing with less demand for resources.
Colors also help with distinguishing between objects of the same shape, and in the case of warnings, provide an instantaneous signal e. You can see many interesting examples of applications of color vision in computers if you search for color computer vision on YouTube.
The images to be processed are either captured by the built-in camera of the unit or provided by the users. They are then analyzed by the computer system. While capturing images is a well-established field, there are still many challenges in color processing because the way the human brain perceives color is very difficult to recreate.
Like with hearing where we react to the frequencies, the sound pressure level, and the duration of the sound, in the vision we gather information about color from the frequency and the wavelength in combination with other complex factors.
For example, the colors of surrounding objects affect our perception of color. From the evolutionary perspective, this adaptation is needed to allow us to adapt to the surrounding environment and to learn to ignore the unimportant aspects of the environment while noticing the aspects that stand out.
Our senses can be tricked because of this tendency to adapt. For example, we may perceive two objects that reflect the light of the same frequency as having different colors, because of the other objects that surround them, as in the illustration of the famous visual illusion. Here we perceive the brown square in the top half of the image second row, second column as being lighter than the square in the second half of the image fifth row, second column.
In reality, both of the squares have the same color, but they are perceived differently because the first one is surrounded by darker colors, while the second — by the lighter colors. It is difficult for computer scientists to create algorithms that take into account all of these factors.
Despite the difficulties, there is considerable progress in the field. This article was written by Kateryna Yuri. Unit Converter articles were edited and illustrated by Anatoly Zolotkov. Do you have difficulty translating a measurement unit into another language? Help is available! Post your question in TCTerms and you will get an answer from experienced technical translators in minutes.
In this part of the TranslatorsCafe. Frequency is the number of occurrences of a repeating event per unit of time. The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency.
Any wave pattern can be described in terms of sinusoidal components. For periodic waves, frequency has an inverse relationship to the concept of wavelength; simply, frequency is inversely proportional to wavelength.
The wavelength of a tuning fork Hz is thus equal to approximately 0. In SI units, the unit of frequency is the hertz Hz. A previous name for this unit was a cycle per second. The SI unit of wavelength is the meter. Note: In this converter conversion between wavelength and frequency are performed for electromagnetic waves only. This online unit converter allows quick and accurate conversion between many units of measure, from one system to another.
The Unit Conversion page provides a solution for engineers, translators, and for anyone whose activities require working with quantities measured in different units. Learn Technical English with Our Videos! You can use this online converter to convert between several hundred units including metric, British and American in 76 categories, or several thousand pairs including acceleration, area, electrical, energy, force, length, light, mass, mass flow, density, specific volume, power, pressure, stress, temperature, time, torque, velocity, viscosity, volume and capacity, volume flow, and more.
Note: Integers numbers without a decimal period or exponent notation are considered accurate up to 15 digits and the maximum number of digits after the decimal point is In this calculator, E notation is used to represent numbers that are too small or too large. E-notation is commonly used in calculators and by scientists, mathematicians and engineers. We work hard to ensure that the results presented by TranslatorsCafe. However, we do not guarantee that our converters and calculators are free of errors.
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Spectra Did you know what would happen to the sound of the violin if we remove all higher harmonics from it leaving only the main frequency? More about Frequency and Wavelength The period of these waves on the Miami Beach coast is approximately 4 seconds.
This cavity magnetron is used in microwave ovens to emit electromagnetic energy into the cooking chamber. The atmosphere is transparent for microwaves in the C-band frequency range 4 to 8 GHz or wavelength 7. This oscilloscope, which measures the voltage of the wall electrical outlet, shows a frequency of Rainbow over Niagara River. Diamond ring. First image: correct cut of a diamond. The light is reflected up towards the eye of the viewer, and the diamond sparkles.
The second and third images show cuts that are too deep and too shallow respectively. Here the light is reflected down into the setting or to the sides, and the diamonds look bleak. Gulls and many other birds have red or yellow oil droplets in the cones of their retinas. This non-contact infrared thermometer determines temperature from the thermal radiation emitted by objects being measured. Green iguana species can detect ultraviolet light.
Viewers with normal color vision should clearly see the number 74 in this Ishihara color test plate. The Canon 5D camera automatically detects human faces and focuses on one of them. Color illusion. Compact Calculator Full Calculator Unit definitions.
Online Unit Converters Photometry — Light. Calculators In this part of the TranslatorsCafe. Wavelength Different types of waves exist in this world, from ocean waves caused by the wind to electromagnetic waves. In particular: This cavity magnetron is used in microwave ovens to emit electromagnetic energy into the cooking chamber Gamma rays have wavelengths up to 0.
X-rays fall between 0. Ultraviolet light , invisible to the human eye, is between 10 nm and nm. The visible spectrum of color light is between nm and nm.
One hertz simply means " one cycle per second" typically that which is being counted is a complete cycle ; Hz means " one hundred cycles per second", and so on.
The unit may be applied to any periodic event—for example, a clock might be said to tick at 1 Hz , or a human heart might be said to beat at 1. The number of hertz abbreviated Hz equals the number of cycles per second. The frequency of any phenomenon with regular periodic variations can be expressed in hertz , but the term is used most frequently in connection with alternating electric currents, electromagnetic waves light, radar, etc.
To calculate the frequency of a wave, divide the velocity of the wave by the wavelength. Write your answer in Hertz , or Hz , which is the unit for frequency. If you need to calculate the frequency from the time it takes to complete a wave cycle, or T, the frequency will be the inverse of the time, or 1 divided by T.
If you are talking about a periodic repetitive signal then a frequency of Hertz can be converted to a period in seconds simply by inverting it mathematically.
Units of measure Nanometer nm , an SI unit of length, equal to 10 - 9 m a thousand-millionth of a meter Nanomolar nM , in chemistry, one thousand-millionth molar. Nautical mile NM or nmi , a unit of length used for maritime and aviation purposes. Wavelength usually is expressed in units of meters. Usually frequency is measured in the hertz unit, named in honor of the 19th-century German physicist Heinrich Rudolf Hertz. The hertz measurement , abbreviated Hz, is the number of waves that pass by per second.
For example, an "A" note on a violin string vibrates at about Hz vibrations per second. The energy of each photon is equal to Planck's constant, multiplied by the frequency of the light, h is always 6. Like hertz , kilohertz is used to measure frequency, or cycles per second. Since one hertz is one cycle per second, one kilohertz is equal to 1, cycles per second.
Since the sound frequency doubles with each octave, the C7 key produces an audible frequency of just over 2 kHz 2, Hz. How do you convert Hz to meters? Category: science physics. Please provide values below to convert hertz [ Hz ] to wavelength in metres [ m ], or vice versa.
Hertz [ Hz ] Wavelength In Metres [ m ] 0. What is a Hertz equal to?
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