Presentation on the topic of types of radiation. Types of radiation Light sources natural artificial
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Types of radiation
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Types of radiation
Thermal radiation - radiation from heated bodies. When fast atoms collide with each other, some of them kinetic energy goes to the excitation of atoms, which then emit light and pass into an unexcited state.
Electroluminescence In a gas discharge, an electric field imparts large kinetic energy to electrons. Fast electrons experience inelastic collisions with atoms. Some of the energy goes into the excitation of atoms. Excited atoms emit light.
Cathodoluminescence is the glow of solids caused by the bombardment of them with electrons.
Chemiluminescence With some chemical reactions going with the release of energy, part of this energy is spent on the emission of light.
1) Fluorescence 2) Phosphoroscence C light excites the atoms of a substance, and after that they glow themselves. Photoluminescence
Fluorescence Some substances have the property of self-luminosity during the time they are exposed to illumination of an extraneous light source. For example, a weak solution of quinine sulfate, acidified with a few drops of sulfuric acid, shines from the surface with a weak bluish light in daylight. The glow immediately disappears as soon as the access of light to the liquid is cut off.
Application of fluorescence Traffic signs on billboards covered with fluorescent film Christmas toys covered with fluorescent paint
Stokes rule the phenomenon of phosphorescence arises in bodies capable of phosphoresis almost exclusively under the influence of light containing rays of short wavelengths - violet and ultraviolet. the photoluminescence wavelength is longer than the exciting light wavelength.
Photoluminescence The phenomenon of photoluminescence is widely used in fluorescent lamps. The Soviet physicist S.I. Vavilov proposed to cover the inner surface of the discharge tube with substances capable of glowing under the influence of radiation from a gas discharge.
A black light lamp is a lamp that emits predominantly in the long-wavelength ultraviolet region of the spectrum (UVA range) and produces very little visible light. To protect documents from counterfeiting, they are often provided with ultraviolet tags that are only visible under ultraviolet light. Disinfection with ultraviolet (UV) radiation. Air sterilization and hard surfaces... Disinfection of water is carried out by chlorination in combination, as a rule, with ozonation or disinfection with ultraviolet (UV) radiation. Chemical analysis, UV spectrometry. UV spectrophotometry is based on the irradiation of a substance with monochromatic UV radiation, the wavelength of which changes over time. The substance absorbs UV radiation at different wavelengths to varying degrees. The graph, the ordinate of which is the amount of transmitted or reflected radiation, and the abscissa is the wavelength, forms a spectrum. Spectra are unique for each substance, which is the basis for the identification of individual substances in a mixture, as well as their quantitative measurement. Catching insects. In medicine (disinfection of premises).
GOKU JSC Comprehensive school at penal institutions "
TYPES OF RADIATION.
SOURCES OF LIGHT.
Physics presentation
Prepared by a physics teacher - G.F. Poleshchuk
Light is electromagnetic waves with a length of 4 · 10¯⁷ - 8 ∙ 10⁻⁷m. Electromagnetic waves are emitted when accelerated movement charged particles. These particles are part of the atoms that make up the substance. In order for an atom to start emitting, it needs to transfer a certain amount of energy. At radiation, the atom loses it. For a continuous glow, an inflow of energy from the outside is required.
TYPES OF RADIATION
* THERMAL RADIATION
* CATHODOLUMINESCENCE
* CHEMILUMINESCENCE
* PHOTOLUMINESCENCE
CHEMILUMINESCENCE- This is a glow that occurs due to the release of energy during certain chemical reactions.
PHOTOLUMINESCENCE- this is the phenomenon of glow of a body directly under the influence of radiation incident on it
In preparing the presentation, Internet resources were used:
bonfire + - + pictures # urlhash =5757898114734803683
http://go.mail.ru/search_images?tsg=l&q= polar + auroras + -photo # urlhash =115382898120037314
http://go.mail.ru/search_images?tsg=l&q= fluorescence + - + photo # urlhash =4067125506694357117
http://go.mail.ru/search_images?fr=spc&q= that% 20 is called% 20 fluorescence% 20% 3 F # urlhash =2632216883017076572
http://go.mail.ru/search_images?q=%20 fluorescence% 20i% 20phosphorescence% 20-% 20photo & fr = web # urlhash =6848376861429583508
Physics textbook-11, G. Ya. Myakishev, B.B. Bukhovtsev, V.M. Charugin, Moscow, "Education", 2014.
Slide 1
Types of radiation Light sources Physics teacher Trifoeva Natalia Borisovna School No. 489, Moscow region of St. PetersburgSlide 2
The light source must consume energy. Light is electromagnetic waves with a wavelength of 4 × 10-7-8 × 10-7 m. Electromagnetic waves are emitted during the accelerated motion of charged particles. These charged particles are part of the atoms that make up matter. There is no light inside the atom. Atoms give birth to light only after they are excited. In order for an atom to begin to radiate, it needs to transfer a certain energy. Radiating, the atom loses the received energy, and for the continuous glow of the substance, an inflow of energy to its atoms from the outside is necessary.
Slide 3
Thermal radiation Thermal radiation is the simplest and most widespread type of radiation, in which the energy losses of atoms for the emission of light are compensated by the energy of the thermal motion of atoms (or molecules) radiating body... The higher the body temperature, the faster the atoms move. When fast atoms (or molecules) collide with each other, part of their kinetic energy is converted into the excitation energy of atoms, which then emit light. The heat source of radiation is the sun, as well as an ordinary incandescent lamp. The lamp is a very convenient but low-cost source. Only about 12% of all the energy released in the lamp filament by electric current is converted into light energy. Finally, the heat source of light is a flame. Grains of soot (fuel particles that did not have time to burn) are heated by the energy released during the combustion of fuel and emit light.
Slide 4
Electroluminescence The energy required for atoms to emit light can also be obtained from non-thermal sources. In a discharge in gases, the electric field imparts large kinetic energy to the electrons. Fast electrons experience inelastic collisions with atoms. Part of the kinetic energy of electrons goes to excite atoms. Excited atoms release energy in the form of light waves. Due to this, the discharge in the gas is accompanied by a glow. This is electroluminescence. The Northern Lights are a manifestation of electroluminescence. Charged particle streams emitted by the Sun are captured magnetic field Earth. They excite the atoms of the upper layers of the atmosphere at the magnetic poles of the Earth, due to which these layers glow. Also, electroluminescence is used in advertising tubes.
Slide 5
Cathodoluminescence The glow of solids caused by the bombardment of them with electrons is called cathodoluminescence. Thanks to cathodoluminescence, the screens of cathode ray tubes of televisions glow.
Slide 6
Chemiluminescence In some chemical reactions that release energy, some of this energy is directly spent on the emission of light. The light source remains cold (it has a temperature environment). This phenomenon is called chemiluminescence. Almost everyone of you is probably familiar with it. In summer, you can see a firefly insect in the forest at night. He has a small green "flashlight" on his body. You won't burn your fingers by catching a firefly. The luminous speck on its back has almost the same temperature as the surrounding air. Other living organisms also have the ability to glow: bacteria, insects, many fish living at great depths. Pieces of rotting wood often glow in the dark.
Slide 7
Photoluminescence Light incident on a substance is partially reflected and partially absorbed. The energy of the absorbed light in most cases only causes heating of bodies. However, some bodies themselves begin to glow directly under the influence of the radiation incident on it. This is photoluminescence. Light excites the atoms of the substance (increases their internal energy), and after that they light up themselves. For example, the glowing paints that are used on many Christmas tree decorations emit light after being irradiated. The light emitted by photoluminescence has, as a rule, a longer wavelength than the light that excites luminescence. This can be observed experimentally. If you direct a light beam through a violet light filter to a vessel with fluorescein (organic dye), then this liquid begins to glow with a green-yellow light, that is, light of a longer wavelength than that of violet light. The phenomenon of photoluminescence is widely used in fluorescent lamps. Fluorescent lamps are about three to four times more economical than conventional incandescent lamps.
PRESENTATION in physics on the topic "Types of radiation" Completed by a student of 11 "B" class Dvigalova Ekaterina 900 igr. net
Infrared radiation Infrared - E vk vf William Herschel (German) 1800 g "thermal" radiation. Radiation source: any body heated to a certain temperature. λ = 0.74 - 2000 μm; Properties: Little absorbed by air, dust; They cause heating of bodies.
The use of infrared radiation IR (infrared) diodes and photodiodes are widely used in remote controls remote control, automation systems, security systems, etc. Infrared emitters are used in industry for drying paint and varnish surfaces. Sterilization of food is also a positive side effect. A feature of the use of infrared radiation in Food Industry is the possibility of penetration of an electromagnetic wave into such capillary-porous products as grain, cereals, flour, etc. Electromagnetic wave a certain frequency range has not only a thermal, but also a biological effect on the product, promotes the acceleration of biochemical transformations in biological polymers (starch, protein, lipids).
Ultraviolet radiation λ: 380 nm - 10 nm; ν: from 7, 9 × 1014 - 3 × 1016 Hz Radiation source: Sun, mercury lamps Properties: William Hyde Wollaston (English) 1801 is intensively absorbed by the atmosphere and is investigated only by vacuum devices; Possesses high chemical and biological activity. Ionizes the air
UFISH increases the tone of a living organism; W activates defense mechanisms; Ш increases the level of immunity, and also increases the secretion of a number of hormones; III substances are formed that have a vasodilating effect, increase the permeability of skin vessels; W changes carbohydrate and protein metabolism in the body; Ш changes pulmonary ventilation - the frequency and rhythm of breathing; gas exchange increases; W is formed in the body of vitamin D, which strengthens the musculoskeletal system and has an antirachitic effect.
X-rays X-ray radiation λ: 10 -14 to 10 -8 m Properties: v High chemical and biological activity; v Ionizes the air; v High penetrating power; v Glow of gases; v Causes mutation in organisms. Wilhelm Konrad Röntgen 1895
Application of RI Medicine. Revealing defects in products (rails, welds, etc.)) using X-ray radiation is called X-ray flaw detection. In materials science, crystallography, chemistry, and biochemistry, X-rays are used to elucidate the structure of substances at the atomic level using X-ray diffraction scattering (X-ray analysis). A well-known example is the determination of the structure of DNA. In addition, with the help of X-rays, it can be determined chemical composition substances. At airports, X-ray television introscopes are actively used, which allow viewing the contents of hand luggage and baggage in order to visually detect dangerous objects on the monitor screen.
