Light 5500. Which light is better: yellow or white? Lighting color temperature

In this article we will use simple examples to show what the technical characteristics of color temperature or “chromaticity” mean in the description of LED lamps.

Color temperature in the description of lamps is measured in degrees on the Kelvin scale (K) and characterizes the shade of their light as perceived by human vision. To make it easier for buyers to understand, manufacturers mark their products not only by indicating the color temperature of the LED lamp, but also by visually matching their shade in the pictures. Warm light is considered to be white light with a yellowish tint, and the lower the degree on the Kelvin scale, the more yellow the tint and the “warmer” the light they emit. Conversely, the higher the specified temperature, the bluer the tint. The most accessible way to evaluate these characteristics is in the figure below:

To make it even easier, we can draw several analogies for the color hue of light between color temperature and the shades of lighting we are familiar with:

800 K- the initial boundary of the red radiation of incandescent objects visible to the eye;
1500-2000 K- light from the fire of an ordinary wax candle;
2700 K— traditional incandescent lamp 40-75 W;
3000 K— a particularly powerful traditional light bulb with an incandescent filament (more than 150 W), a halogen light bulb;
3400 K— the light of the sun on the horizon;
4200 K- a standard fluorescent lamp, the so-called “tube” shape - they are often used in entrances, offices, corridors (visually, this is still a relatively warm white light);
4300-4500 K- sunshine in the morning and at 14-15 hours;
4500-5000 K— light from most automobile xenon lamps;
5000 K- sunlight at midday (about 12 hours);
5500-5600 K— camera flash;
6500-7500 K— light in cloudy weather;
7500-8500 K- light in the evening during sunset;
9500 K- the light of the blue clear sky at sunrise;
15000 K- deep blue light, characteristic of a clear winter sky.

The first household LED lamps featured a bright white light with a noticeable bluish tint. The color temperature of such lamps was at the level of 5500-6500K. This shade of light is normally perceived by a person on the street and is very similar to bright daylight, but indoors such light turned out to be not very comfortable for a person. For example, light from conventional incandescent lamps ranges from 2500 to 3000 degrees Kelvin and has a distinct yellowish tint, which is very comfortable for the eyes. It is for this reason that manufacturing technologies for LED lamps have been improved to convert their emission spectrum to lower temperatures, and most LED lamps for household purposes today have similar color characteristics to conventional incandescent lamps.

LED lamps have begun to actively penetrate not only household, but also office, public (shops, theaters, galleries) and industrial lighting, where a different shade of light is needed. Therefore, the choice of lighting shade when purchasing lamps is already quite worthy and it is possible to choose an LED lamp and luminaire for any purpose.

Articles about LED lighting

This article is for those who have asked a similar question for the first time and do not have a technical education. LED lighting is the lighting of something using relatively new light sources - LEDs. An LED is an industrially created crystal that, when connected to electricity, begins to emit light. To be fair, LED cannot be called a new light source, because... it was invented several decades ago, but it began to be actively developed and used in all spheres of our lives only at the beginning of 2000, thanks to new discoveries in the technological field and a significant reduction in production costs.

Modern technologies do not stand still and scientific and technological progress does not ignore such an area of our lives as lighting. Development is taking place both in the direction of increasing lighting technical characteristics and in the direction of the emergence of additional related technological devices that increase the usefulness of lamps and lighting systems in general. We are talking about numerous varieties of LED lights with built-in sensors.

We decided to make a review in which the most interesting reviews about LED lamps will be collected. We collected these reviews both from our customers (and continue to collect) and from the Internet - from various forums, blogs, thematic portals and other resources. Having received a large amount of data, we systematized it, anonymized it, and we got a certain set of interesting opinions and advice from real people who use LED lamps at home, in the country, in the office, etc.

Customers of our online store often ask questions - which LED lamps are the best, from which companies? Why exactly are they better? Can you trust the characteristics of the lamps indicated on the packaging? Is it possible to buy LED lamps made in China? Can LED lamps be used in children's rooms? These are just some of the questions that buyers ask when choosing the best option for themselves. Moreover, such questions arise when the buyer already knows what type of lamps is needed and with what characteristics. In this article we will try to answer all these questions and avoid new puzzles for the consumer :-)

An LED is a semiconductor device that transforms electric current into light radiation. LED has a generally accepted abbreviation - LED (light-emitting diode), which literally translated into Russian means “light-emitting diode”. The LED consists of a semiconductor crystal (chip) on a substrate, a housing with contact leads and an optical system. The light emission directly comes from this crystal, and the color of the visible radiation depends on its material and various additives. As a rule, there is one crystal in the LED housing, but if it is necessary to increase the power of the LED or to emit different colors, several crystals can be installed.

This is, of course, the most important issue, since the world today is on the threshold of a new era in lighting technology and we need to be sure that LED lighting is not harmful to health. To date (2014), this issue cannot be considered thoroughly studied, since the period of introduction of LED lighting into human life is still quite short and the necessary amount of statistical data for analysis has not yet been accumulated. However, at the moment there is a huge amount of facts and opinions of professionals in this field, indicating the absence of any harm from LED lighting.

This article is for those who do not understand light bulbs, the types of their sockets and electricity in general, but already understand that using LED lamps is much more economically profitable than incandescent lamps and even than fluorescent lamps (they are often called “energy saving”). Selecting the right LED lamps is very simple and we will help you make the right choice by following the instructions below. Or you can call us right away and we will be happy to help you with your choice.

In this article we will talk about the benefits of using LED lamps compared to fluorescent (often called "energy saving"), halogen and incandescent lamps. In the second part we will provide an economic calculation of the payback when replacing lamps with LED ones. The economic efficiency of LED lamps is so obvious that you do not need any special knowledge to draw your own conclusions.

One of the challenges that is often encountered during deep renovation or construction of residential and office premises is the level of sufficient lighting. In a situation where ordinary incandescent lamps are used as light sources, from experience you can roughly determine the required number and power of light bulbs, but if you have an idea to make your home more modern and comfortable, and at the same time regularly save quite significant amounts on lighting, then It makes sense to take a closer look at LED lighting. So, how many and what kind of LED lamps do you need to install to make the room comfortable?

In one of our articles we talked about what an LED is and how it developed. Now we want to dwell in more detail on the current industry leaders - those who produce LEDs and LED lamps. This is not the same thing, since lamp manufacturers do not always make LEDs and, conversely, LED manufacturers do not always mass produce lamps based on them. According to official data from IMS Research, as of February 2013, LED production is concentrated in China (more than 50%), then Taiwan (about 20%), South Korea (about 10%), Japan, USA, Europe and other regions (total 20%) .

This article is a practical guide for those who are planning to make major renovations in an apartment or house and are thinking about how to make the lighting of their future home comfortable, cozy, unique, easy to maintain, but at the same time economical and environmentally friendly. Today, indeed, there is something to think about, since LED lighting is becoming very inexpensive. The choice of power, size and external design of light sources is very rich and you don’t have to limit your imagination. Where to start? How to approach the task correctly? To do this, you need to understand what exactly you want to do, and then find the most effective solutions from both a practical and economic point of view. It is not as difficult as it seems and we will be happy to help you with this.

In our online store you can purchase LED lamps and LED luminaires, choosing them to suit the task of illuminating any object. But our activities are limited not only to sales - our team also includes highly experienced engineers in the field of design, production, installation and further operation of lighting control systems. Our partners are many engineering and design companies, together with whom we can implement projects for lighting systems for objects of any scale and complexity. This area of activity of our company is presented on the market as the WLightiT project.

In this article we will touch on a very important topic - office lighting. A third of most people's lives are spent at work, so the quality of lighting in the workplace is key to well-being and productivity. That is why, when planning lighting in an office space, it is important to take into account the main factors affecting the quality of lighting. The quality of lighting is affected even by seemingly trifles such as the color of the walls, the arrangement and material of the furniture. In our article, we briefly classify office lamps so that you can get a first idea of the variety of lighting solutions in office lighting, but we will focus on office lamps implemented using LEDs as light sources.

When creating an interior, designers use many ways to change the surrounding space, usually using color, shape and perspective. Also an important factor in creating the mood and overall appearance of the room is the color temperature of light from artificial lighting sources. In everyday life, this concept is usually limited to such concepts as “cold” and “warm” color.

In order to correctly place accents with the help of light, emphasize the advantages of the interior and hide its shortcomings, you need to know what is hidden under this concept.

Color temperature unit

A parameter such as color temperature relates to physics and is measured in degrees Kelvin (˚K). Absolute zero in the color temperature table is black. Next in order of increasing color temperature is dark red, which has a temperature of 800˚ Kelvin. Bright red corresponds to a temperature of 1300˚K, and orange - 2000˚K.

Shades of yellow range from 2500 to 5000˚K, and neutral white light corresponds to a temperature of 5500˚K.

Paradoxically, blue, which is considered cold in everyday life, has the highest color temperature - 9000 ˚K.

To find out the color temperature of a lamp, carefully study its packaging; this parameter is necessarily displayed on it.

It is worth understanding that this value is comparative and the lamp does not heat up to such temperatures.

Psychology of color

To choose the right artificial lighting lamps, you need to know exactly what room they are intended for. For example, a warm orange color will add coziness to the living room, bedroom or guest area of a restaurant, while neutral white will set you in a more work-oriented mood.

Lamps with white light will fit well into the interior of a study, kitchen or office. Warm yellowish color is suitable for living rooms. It is quite bright, but at the same time warm and conducive to relaxation and anxiety relief.

It is undesirable to use lamps with a bluish glow in the interior of a home, as it has an element of “sterility”. This lighting is more suitable for public places: hospitals, shops, offices.

When choosing lighting lamps, it is often necessary to focus not only on the aesthetic component, but also take into account the functions of the room. To understand which color temperature is best for the eyes, you need to take this specificity into account.

So in the workplace it is better to use fluorescent lamps - they tire the eyes less and distort the colors and shape of surrounding objects. The best choice would be lighting with a color temperature of 4000 to 4500 ˚K. For reading, a lamp with a cool white glow and a range of up to 6500 ˚K is much better suited.

Distortion of colors

Depending on the color emitted by artificial lighting lamps, the color of surrounding objects may visually change. This fact is important to know when creating a home design, because the final result of the design work depends on the choice of lighting fixture.

With the right lighting, you can either soften or completely remove the surrounding colors. So, in order to “tame” the red color in the interior a little, it is necessary to install lamps with a soft orange color in the lamps. Orange will become more gentle and calm under yellow lighting.

The green color of furniture and walls gives more choice when installing lamps. Warm yellow or orange light will change the green to a soft light green, and a color from the blue spectrum, on the contrary, will turn it into a bright, bold aqua color.

The most capricious in terms of lighting is blue and light blue. They require strict use of lamps with white, neutral light.

Trying to make the interior more expressive, many make serious mistakes when choosing lighting. So, when installing lamps with blue light, you can completely remove the yellow color from the interior - it will turn into an inexpressive gray. The most mistakes are made when lighting an interior with purple furniture or walls.

Lamps with a low color temperature turn violet into red, which radically changes the surrounding space. For this reason, it is necessary to choose lamps with a color temperature of 5000˚K.

To independently determine which lighting is best suited for your home, buy 3 lamps with color temperatures of 2500˚ K, 4000˚ K and 6000˚ K and try installing each of them one by one. In this case, it is better to take a photo of the interior at each color temperature in order to clearly make a choice.

Color rendition

In addition to color temperature, when choosing lamps you need to become familiar with the concept of “color rendering”. This parameter is indicated on the packaging with the Ra index and is determined by the lamp’s ability to accurately convey the natural color of the object illuminated by the lamp. A good color rendering index is 80 Ra and higher. Such lighting will not distort the original colors.

Depending on the type of lamps, they initially have different color rendering indices. Thus, incandescent lamps and halogen lamps have a maximum color rendering level of 99-100 Ra, which makes their indicators standard.

LED, metal halide and fluorescent lamps with a five-component phosphor have an index of 90, which makes their color rendering very good.

Fluorescent lamps with three-component phosphor have the worst performance, ranging from 80 to 89 Ra. Mercury and some LED lamps have much worse performance; they boast meager parameters of 40-59 Ra. Sodium lamps have the worst performance; their Ra index is less than 39, which is a very poor result.

Photo color temperature

Properly organized lighting plays an important role in everyday life. The color of the light flux created by a light bulb affects our state, perception of the environment and the shades of objects. Let's figure out which light, warm or cold, will be better for the eyes, and how to choose lighting for different areas of the apartment.

How does the shade of light affect a person?

There is no direct connection between the color of lamps and eye health. This means that, trying to maintain normal visual acuity, you don’t have to worry about what shade of light to choose for your office or living room.

Nevertheless, color temperature indirectly affects the health of the inhabitants of the room, affecting mood and general psycho-emotional state.

Cold glow tones, increases concentration, dispels drowsiness, and is therefore recommended for illuminating work areas.
The warm tone of light is characterized by the opposite properties: it relaxes, soothes, creates an atmosphere of comfort and coziness.

The human eye is capable of detecting changes in color temperature in the widest range – 800–20,000 K.

Selecting a light source

To find out what shade of light a regular or energy-saving light bulb emits, look at the color temperature of the product, which is printed on the packaging.

The temperature of light is measured in Kelvin (K). A yellow glow is produced by a light bulb with a lower value of this value. And at a high color temperature, the light from the device will be cold and slightly bluish.

The most common lamps with the following shades of light:

Cool white, which corresponds to values from 5400 to 5000 K.
Natural (neutral) white with a temperature of 3500 to 5000 K.
Warm white with a range of values from 2700 to 3500 K.

The differences between light at different temperatures are shown in the photo.

Which shades of light are best suited for different areas of the room?

Let's find out which glow colors are suitable for different rooms and areas.

Cold spectrum light

The glow in the cold temperature range is close in perception to the eye to the light of the sun in the winter season. It is ideal for work areas of an apartment or office. Cold light lamps:

looks brighter;
stimulates mental activity;
helps you concentrate and get ready for work;
suitable for work spaces with combined lighting - artificial and natural.

Pay attention! Cold glow distorts the color scheme of objects painted in warm colors. Orange will appear brownish, yellow will appear green, red will appear purple. At the same time, the green and blue palette becomes brighter and deeper.

You also need to take into account that the final color of the lighting depends on the color of the lampshade and the bulb of the device.

Lamps with high color temperatures will find application:

In the washbasin area in the bathroom. The cold glow invigorates and stimulates brain activity, promoting a speedy awakening.
In the kitchen area. Spot lighting is used here to help the housewife increase organization and productivity.
In large rooms with ultra-modern design.
In work areas and offices to increase concentration and mental alertness.

You should not use lamps with a cold glow in bedrooms and living rooms, where apartment residents relax in the evening. Scientists have found that bluish light slows down the production of melatonin, a hormone that is responsible for biorhythms and healthy sleep.

Neutral white lighting

Neutral electric lighting is optimal for rooms where you have to stay for a long time. Certain types of fluorescent and halogen lamps allow you to achieve a glow close to that of the sun. This backlight does not affect the tones of surrounding objects, so there is no fear of color distortion when it is turned on.

Above mirrors to see the most accurate reflection without distorted colors.
In corridors and hallways for quick adaptation of vision after street light.
In a child's room where a natural lighting tone is desired.
In kitchens and dining rooms, where owners spend a lot of time.
In places intended for reading.

Warm spectrum lighting

Light with a temperature of 3500–2700 K has a cozy, warming yellowish tint that is well perceived by the eyes. Such a glow is subconsciously associated with the morning or evening sun.

Both traditional incandescent lamps and halogen lamps can emit the yellow-tinged light we are used to. Fluorescent illuminators and LED devices with a low color temperature are also produced.

Light in the warm range enhances the color saturation of objects made in a pastel palette. Interior designers actively use this feature to create unique images. Details of cold tones with such lighting will become less expressive.

Important! Due to the absence of rays of the appropriate spectrum, cold colors under a yellow glow look distorted. Blue approaches green, blue turns black, violet turns red.

Yellowish warm light would be appropriate:

In the canteens. During meals, such lighting will make dishes more attractive and promote good digestion.
In bedrooms to create coziness and a calm atmosphere.

In the living rooms. Warm lighting will add ease and lightness to the atmosphere and relieve psychological stress for guests and apartment owners. A diffuser chandelier in this room will be the ideal solution.
In the bathroom, in the bathtub area, for relaxation and creating a sense of tranquility necessary to relax and get the maximum benefit from relaxing water treatments.

Additional options

In addition to the color temperature of the lighting device, other characteristics of the lamps are also important. There are several main criteria that need to be taken into account when choosing:

Operating principle. There are incandescent, halogen, LED and fluorescent lamps.
Efficiency. In the first place in this parameter are LED devices.
Flask device. It can have the shape of a ball, tube, mushroom, pear, spot.
Price. Incandescent lamps will cost less. LED ones are more expensive than others, but the one-time overpayment will pay off over time with lower power consumption.
Color rendering index. Indicated on the device packaging by the letters Ra. If it is equal to or exceeds 90, then the colors of the interior when illuminated by this product will remain natural, as in daylight. At a value of 80 and below, be prepared for distortion of the usual colors.

It cannot be said that a certain light tone - cold or warm - is better or worse. Each of them affects a person in a certain way, so it is important that the color of the lighting matches the purpose of the room or functional area.

The color temperature of LED lamps is one of the parameters that characterizes the quality and shade of light, and also partly determines the brightness level of the lighting element. When choosing, be sure to pay attention to the color temperature. If the llama is chosen incorrectly, it will be difficult to ensure a feeling of comfort in the room.

Light source in Kelvin

In earlier times, when incandescent lamps were mainly used, characterized by a standard color temperature, this parameter did not play as significant a role as it does today.

With the advent of LED emitters, the task of selection has become more complicated, since the shade of light in this case is determined by the semiconductor material. Therefore, we should consider in more detail what this parameter is. The unit of measurement is degrees, K (Kelvin scale).

The range of values is very wide: from 1,800 to 10,000 K. However, for residential, office premises, and public facilities, the most preferable are lamps whose colors lie in the range of 2,700-6,600 K. Conventionally, several ranges are distinguished:

2,700-3,200 K (warm white glow);
3,500-4,500 K (neutral or daylight);
4,700K-6,000K (white);
over 6,000 K – cold white glow.

For comparison, an incandescent lamp is characterized by a color temperature from the first group. That is why light sources with such properties are more comfortable, and a warm glow adds coziness to the interior. The working atmosphere is created by lamps with neutral white light.

Features of the office lighting system

The recommended shade of radiation in workplaces is characterized by a value of 4,200 to 5,500 K, i.e. white or neutral light is preferable. This is due to the fact that in such conditions the performance will be maximum (up to 100%).

Choosing lighting for office spaces

With other lighting (yellow, red, blue, cyan and orange tints), labor productivity is noticeably reduced, especially when it comes to orange light (about 80%).

The expediency of using lamps with neutral or white radiation in a working atmosphere is explained by the fact that they contain a blue spectrum, which in the daytime helps to concentrate attention and speed up reactions.

All these factors are good for work when it is important to increase labor productivity.

Color temperature in residential areas

What is good for an office is not always beneficial in a private home or apartment. For example, light in which the blue spectrum predominates is not recommended for use in a nursery, bedroom, i.e. in rooms where a person is at night. For each room of private housing, there are individual recommendations for organizing a lighting system.

For example, living rooms and bedrooms should be equipped with lamps with lamps whose lighting temperature ranges from 2,700 to 3,200 K (warm white). This glow will add coziness to the room.

, it is recommended to equip kitchens with emitters with a color temperature of 4,000-5,000 K (daylight, white light). Radiation with this spectrum is also preferable for the reading area, home office, as well as local lighting (for example, near a mirror in the bathroom).

Bright white and cool light with a color temperature of 5,000-6,500 K is also suitable for kitchens and bathrooms. This type of lighting is ideal for a garage as it creates a special atmosphere conducive to work.

Lamp brightness and color level

The glow intensity of a light source is determined by a number of parameters: power, color temperature, type of emitters (diodes) and diffuser. There is no direct relationship between the spectrum and the brightness level, but this parameter still determines the efficiency of the glow, although it is not the key one. For example, lamps with the same power, but with a different emission spectrum will provide different glow intensities.

Brightness and color

This is because lighting a lamp with a higher value (cool shades of 6,000 K and above) produces the brightest light. But this rule only applies if the other parameters (type of diodes, power level) are equivalent for different lamps.

If we compare a light source with a power of 18 and 5 W with different radiation spectrums (3,000 K in the first case and 5,000 K in the second), then it is obvious that an 18 W bulb will be more efficient, despite the fact that the color temperature of the radiation is noticeably below.

We must also not forget about such a concept as degradation, which means the natural process of clouding (decrease in luminescence intensity) of crystals. After a certain period of time, all diode lamps gradually become less efficient. In order for the light source to last longer, you need to select reliable brands.

Thus, color temperature is one of the key parameters of a modern lighting element. If you ignore it, the lighting system may not be effective enough due to an unpleasant glow and low light brightness.

For rooms with different purposes, there are individual recommendations that allow you to choose the most suitable lighting option. For the kitchen, bathroom - white or neutral light. In the bedroom, nursery and living room it is better to use warm light sources.

Introduction………………………………………………………………………………… 1. The concept of color temperature…………………………………………………………… ….. 1.1. Table of numerical values of color temperature of common light sources………………………………………………………………………………….. 1.2. XYZ chromaticity diagram………………………………………………….

1.3.Sunlight and Color Rendering Index (CRI - color rendering index)..

2. Methods for measuring color temperature……………………………...... Sources of information……………………………………………………….

Introduction.

According to our psychological sensations, colors are warm and hot, cold and very cold. In fact, all colors are hot, very hot, because each color has its own temperature and it is very high. Any object in the world around us has a temperature above absolute zero, which means it emits thermal radiation. Even ice, which has a negative temperature, is a source of thermal radiation. It's hard to believe, but it's true. In nature, the temperature of -89°C is not the lowest; even lower temperatures can be achieved, however, for now, in laboratory conditions. The lowest temperature that is currently theoretically possible within our universe is the temperature of absolute zero and it is equal to -273.15 ° C. At this temperature, the movement of the molecules of the substance stops and the body completely stops emitting any radiation (thermal, ultraviolet, and even more so visible). Complete darkness, no life, no warmth. Some of you may know that color temperature is measured in Kelvin. Anyone who bought energy-saving light bulbs for their home saw the inscription on the packaging: 2700K or 3500K or 4500K. This is precisely the color temperature of the light emitted by the light bulb. But why is it measured in Kelvin, and what does Kelvin mean? This unit of measurement was proposed in 1848. William Thomson (aka Lord Kelvin) and officially approved in the International System of Units. In physics and sciences directly related to physics, thermodynamic temperature is measured in Kelvin. The beginning of the temperature scale report begins at the 0 Kelvin point, which means - 273.15 degrees Celsius. That is, 0K is absolute zero temperature. You can easily convert temperature from Celsius to Kelvin. To do this, you just need to add the number 273. For example, 0°C is 273K, then 1°C is 274K, by analogy, a human body temperature of 36.6°C is 36.6 + 273.15 = 309.75K. That's how it all works out just like that.

Chapter 1. The concept of color temperature.

Let's try to figure out what color temperature is.

Light sources are bodies heated to high temperatures, the thermal vibrations of whose atoms cause radiation in the form of electromagnetic waves of various lengths. Radiation, depending on the wavelength, has its own color. At low temperatures and, accordingly, at longer waves, radiation with a warm, reddish color of the light flux predominates, and at higher temperatures, with a decrease in wavelength, with a cold, blue-blue color. The unit of wavelength is nanometer (nm), 1nm=1/1,000,000mm. Back in the 17th century, Isaac Newton, using a prism, decomposed the so-called white daylight and obtained a spectrum consisting of seven colors: red, orange, yellow, green, blue, indigo, violet, and as a result of various experiments he proved that any spectral color can be obtained by mixing light fluxes consisting of different ratios of three colors - red, green and blue, which were called the main ones. This is how the three-component theory appeared.

The human eye perceives the color of light thanks to receptors, the so-called cones, which have three varieties, each of which perceives one of the three primary colors - red, green or blue and has its own sensitivity to each of them. The human eye perceives electromagnetic waves in the range from 780 to 380 nanometers. This is the visible part of the spectrum. Consequently, the light receivers of information carriers - cinema and photographic film or the camera matrix must have a sensitivity to color identical to the eye. Sensitized films and matrices of video cameras perceive electromagnetic waves in a slightly wider range, capturing infrared radiation (IR) close to the red zone in the range of 780-900 nm and ultraviolet (UV) radiation close to the violet in the range of 380-300 nanometers. This region of the spectrum, in which geometric optics and photosensitive materials operate, is called the optical range.

In addition to light and dark adaptation, the human eye has so-called color adaptation, thanks to which it correctly perceives colors under different sources, with different ratios of wavelengths of primary colors. The film and matrix do not have such properties; they are balanced to a certain color temperature.

The heated body, depending on the heating temperature, has a different ratio of different wavelengths in its radiation and, accordingly, different colors of the light flux. The standard by which the color of radiation is determined is an absolute black body (ABB), the so-called. Planck emitter. An absolutely black body is a virtual body that absorbs 100% of the light radiation incident on it and is described by the laws of thermal radiation. And color temperature is the temperature of the black body in degrees Kelvin, at which the color of its radiation coincides with the color of the given radiation source. The difference between the temperature scale in degrees Celsius, where the freezing point of water is taken as zero, and the scale in Kelvin degrees is -273.16, because the starting point in the Kelvin scale is the temperature at which any movement of atoms in the body stops and, accordingly, any radiation stops , the so-called absolute zero, corresponding to a Celsius temperature of -273.16 degrees. That is, 0 degrees Kelvin corresponds to a temperature of -273.16 degrees. Celsius.

The main natural source of light for us is the Sun and various light sources - fire in the form of a fire, matches, torches and lighting devices, ranging from household appliances, technical devices to professional lighting devices created specifically for cinema and television. Both household and professional appliances use various lamps (we will not touch on their operating principles and design differences) with different energy ratios in their emission spectra of primary colors, which can be expressed by the value of color temperature. All light sources are divided into two main groups. The first, with a color temperature (Tc.) 5600 0K, of white daylight (DS), the radiation of which is dominated by the short-wave, cold part of the optical spectrum, the second - incandescent lamps (LN) with Tc. - 32000K and the predominance of the long-wave, warm part in the radiation optical spectrum.

Where does it all begin? Everything starts from scratch, including light radiation. Black color is the absence of light at all. From the point of view of color, black is 0 radiation intensity, 0 saturation, 0 hue (it simply does not exist), it is the complete absence of all colors at all. Why we see an object black is because it almost completely absorbs all the light falling on it. There is such a thing as a completely black body. An absolute black body is an idealized object that absorbs all radiation incident on it and does not reflect anything. Of course, in reality this is unattainable and absolutely black bodies do not exist in nature. Even those objects that seem black to us are not actually completely black. But it is possible to make a model of an almost completely black body. The model is a cube with a hollow structure inside; a small hole is made in the cube through which light rays penetrate into the cube. The design is somewhat similar to a birdhouse. Look at picture (1).

Figure (1). – Model of a completely black body.

Light entering through the hole will be completely absorbed after repeated reflections, and the outside of the hole will appear completely black. Even if we paint the cube black, the hole will be blacker than the black cube. This hole will be a completely black body. In the literal sense of the word, the hole is not a body, but only clearly demonstrates to us an absolutely black body.

All objects exhibit thermal radiation (as long as their temperature is above absolute zero, that is -273.15 degrees Celsius), but no object is a perfect thermal emitter. Some objects emit heat better, others worse, and all this depending on different environmental conditions. Therefore, a black body model is used. A completely black body is an ideal thermal emitter. We can even see the color of a blackbody if we heat it up, and the color we see will depend on what temperature we heat the blackbody to. We have come close to the concept of color temperature.

Look at picture (2).

Figure (2). – The color of an absolutely black body depending on the heating temperature.

a) There is an absolutely black body, we don’t see it at all. Temperature 0 Kelvin (-273.15 degrees Celsius) is absolute zero, the complete absence of any radiation.

b) Turn on the “super-powerful flame” and begin to heat up our absolutely black body. The body temperature, through heating, increased to 273K.

c) A little more time has passed and we already see a faint red glow of a completely black body. The temperature increased to 800K (527°C).

d) The temperature rose to 1300K (1027°C), the body acquired a bright red color. You can see the same color glow when heating some metals.

e) The body has heated up to 2000K (1727°C), which corresponds to an orange glow. Hot coals in a fire, some metals when heated, and a candle flame have the same color.

f) The temperature is already 2500K (2227°C). The glow at this temperature becomes yellow. Touching such a body with your hands is extremely dangerous!

g) White color – 5500K (5227°C), the same color of the Sun’s glow at noon.

h) Blue color of the glow – 9000K (8727°C). In reality, it will be impossible to obtain such a temperature by heating with a flame. But such a temperature threshold is quite achievable in thermonuclear reactors, atomic explosions, and the temperature of stars in the universe can reach tens and hundreds of thousands of Kelvin. We can only see the same blue tint of light, for example, from LED lights, celestial bodies or other light sources. The color of the sky in clear weather is approximately the same color. To summarize all of the above, we can give a clear definition of color temperature. Color temperature is the temperature of a completely black body at which it emits radiation of the same color tone as the radiation in question. Simply put, 5000K is the color that a black body acquires when heated to 5000K. The color temperature of orange is 2000K, which means that a completely black body must be heated to a temperature of 2000K for it to acquire an orange glow.

But the color of the glow of a hot body does not always correspond to its temperature. If the flame of a gas stove in the kitchen is blue-blue, this does not mean that the flame temperature is above 9000K (8727°C). Molten iron in its liquid state has an orange-yellow hue, which actually corresponds to its temperature, which is approximately 2000K (1727°C).