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Text content of presentation slides: dispersion of light. DISPERSION Dependence of the speed of light in a substance on the oscillation frequency (or wavelength) DISPERSION Dependence of the refractive index of light on the oscillation frequency (or wavelength) Isaac Newton Dispersion 1666 I. Newton's experience S P E K T Rspectrum (lat.) - insight. I. Newton's experience I. V. Goethe Newton's light is light “tormented by all kinds of instruments of torture – slits, prisms, lenses” Each color has its own length and frequency of the wave. 760 - 620 nm 620 - 590 nm 590 - 560 nm 560 - 500 nm 500 - 480 nm 480 - 450 nm 450 - 380 nm the phenomenon of decomposition of white light into a spectrum. White light is complex, consisting of monochromatic colors. The refractive index of a medium depends on the color of the light (violet, red). The refractive index of light in a medium depends on its frequency. Thomas Young Red + Green + Blue = White light 1807 A17 When white light passes through red glass, the light becomes red. This is due to the fact that light waves of other colors are mainly 1) reflected 2) scattered 3) absorbed 4) refracted A17 sunlight Rainbows form on raindrops. This is due to the fact that white light consists of electromagnetic waves with different wavelengths, which are differently absorbed by water drops 1) Absorbed 2) reflected 3) polarized 4) refracted A17 Do the frequency and wavelength of light change when it passes from water to vacuum? 1) the wavelength decreases, the frequency increases 2) the wavelength increases, the frequency decreases 3) the wavelength decreases, the frequency does not change 4) the wavelength increases, the frequency does not change A17 Do the frequency and wavelength of light change when it passes from vacuum to water? Choose the correct statement 1) the wavelength decreases, the frequency increases 2) the wavelength increases, the frequency decreases 3) the wavelength decreases, the frequency does not change 4) the wavelength increases, the frequency does not change A16 Dispersion manifests itself in the following phenomena: A. change in the visible color of a white fabric when viewed through colored glass. B. A rainbow is formed when light passes through small drops of water. The statement(s) is true(s): 1) only A2) only B3) both A and B 4) neither A nor B (see figure), a beam of blue light falls. What is the speed of light at this ISO after reflection from the mirror if the angle of incidence is 60°? The speed of light from a stationary source in vacuum is c.1) 2) С 3)с-2v 4)c+2v The following optical phenomena occur in a water drop: Refraction of light Dispersion of light, i.e. decomposition of white light into a spectrum Reflection of light Homework.
Dispersion - sounds great word; Beautiful and the phenomenon itself It is close and familiar to us from childhood, We have observed it hundreds of times! The thunder has died down, the summer downpour has died down quickly; And a rainbow hung over the freshly washed earth With a disembodied bridge, Captivating us with its beauty. Dispersion here "had a hand in it." The usual white ray of light She, as if spread out in a prism, In the raindrop he met.
Outstanding English physicist and mathematician, founder classical mechanics. I. Newton was born into the family of a poor farmer in the town of Woolsthorpe, near the town of Grantham. At the age of 12, he began studying at Grantham School. In 1661, Newton entered one of the colleges of the University of Cambridge and upon graduation received degree bachelor. An exceptional role in Newton's life was played by 1665 - 1667, which he spent in his native Woolsthorpe, hiding from the plague. Here he basically developed those ideas that led the scientist to important discoveries: the creation of the mathematical basis of physics - differential and integral calculus, the discovery of the law gravity, to the invention mirror telescope; here he conducted experiments on the decomposition of light. In 1668, Newton was awarded a master's degree, and then he headed the physical and mathematical department at the University of Cambridge. In 1672 He was elected a member of the Royal Society of London, and in 1703. Became its president.
Newton's experiments Newton sent a white beam to a glass prism. As soon as visible light enters the prism, it is refracted and decomposed into an iridescent strip, which is called the spectrum. White color is conventionally divided into seven colors. As experience has shown, each color has its own refractive index: the largest is violet, the smallest is red. As we already know from light diffraction experiments, colors have different wavelengths. Light passing through a trihedral prism is refracted and, upon exiting the prism, deviates from its original direction towards the base of the prism. The magnitude of the deflection of the beam depends on the refractive index of the substance of the prism, and, as experiments show, the refractive index depends on the frequency of the light.
The considered experiments were first made in 1666 by the English physicist Isaac Newton. The figure shows one of the experiments set by Newton himself. Newton in his experiments used sunlight, which he passed into the room through a narrow hole in the window shutter.
Each color corresponds to its own wavelength and frequency, such a single-color light is called - monochromatic Color Wavelength, nm Section width, nm Red Orange Yellow585 - Green Blue510 - Blue480 - Violet
CONCLUSIONS FROM NEWTON'S EXPERIMENTS White light is not monochromatic. The second prism only refracts the rays, but does not change their color. These rays were called simple or monochromatic. White light consists of monochromatic - simple colors. The refractive index of a medium depends on the color of the light: rays of red light in any medium are refracted more weakly than all others. When leaving the prism, white light is decomposed into seven colors: red, orange, yellow, green, blue, indigo, violet. The red light is deflected the least, the violet the most. Light with different wavelengths propagates through a medium with different speeds: purple with the smallest, red with the largest since n = c/v.
COLORS OF OPAQUE BODIES The variety of colors and shades in the world around us explains the phenomenon of dispersion. When interacting with different bodies, rays of light of different colors are reflected and absorbed by these bodies in different ways. Bodies painted white reflect rays of light of different frequencies equally well. Bodies painted black absorb light rays of different frequencies equally well. Opaque bodies are painted in the color whose rays of light they reflect well. With the help of light dispersion, such a phenomenon as a rainbow can be explained.
COLORS OF TRANSPARENT BODIES COLORS OF TRANSPARENT BODIES The color of a transparent body is determined by the composition of the light that passes through it. If a transparent body uniformly absorbs the rays of all colors, then in transmitted white light it is colorless, and in colored light it has the color of those rays with which it is illuminated. When white light is passed through tinted glass, it lets through the color it is painted with. This property is used in various light filters.
GENERALIZATION OF THE MATERIAL Dispersion of light is the phenomenon of decomposition of white light into a spectrum with the help of a prism. The order of the colors in the spectrum does not change. The dispersion of light occurs because the refractive index of the medium depends on the color of the light. The dispersion of light proves that white light is complex, consisting of simple - monochromatic colors. Dispersion helps explain colors transparent bodies, so that the body differently reflect and absorb light of different frequencies.
Consolidation. 1. Observe the formation of colored circles around the light bulb street lamp and explain this phenomenon, note the sequence of circles. (The explanation should be related to the refractive index of colored rays with the propagation velocity Vcr.> Vf) 2. Why do we see white - white, black - black, red - red? 3. Observe a white sheet of paper through colored glass and explain why the paper takes on the color of glass? Vph) 2. Why do we see white - white, black - black, red - red? 3. Observe a white sheet of paper through colored glass and explain why the paper takes on the color of glass?"> 
4. “Excellent” and green “good” are written on the notebook in red pencil. There are two glasses, red and green, which one should be looked through to see the “excellent” rating? 5. On the gray background of the stage is a figure in red. What kind of light should be illuminated to create the appearance of disappearance? 6.From the story of Jules Verne " green beam": "Have you ever seen the setting sun on the horizon? - Yes, sure! “… But have you noticed how the last ray of sunshine appears and goes out when the air is freed from fog and becomes transparent? – Probably not! And so, if you imagine seeing this phenomenon - it happens very rarely - then pay attention to the fact that this last ray will not be red, but green. Yes, yes, will have a wonderful green color, that is, such a green that no artist can create on his palette. Such a green color cannot be found anywhere in nature, because it cannot be found in flora, despite all the multitude and diversity, and near the brightest seas "
slide presentation
Slide text: Light dispersion Lesson for studying new material Grade 11 Physics teacher Tulyupa Iraida Borisovna Municipal budgetary educational institution « high school No. 17 "of the city of Ryazan
Slide text: The world around us plays with colors: we are pleased and excited by the blueness of the sky, the greenery of grass and trees, the red glow of the sunset, the seven-color arc of the rainbow. How can one explain the amazing variety of colors in nature?
Slide text: The purpose of the lesson: to give a concept of the dispersion of light, to explain the dispersion from the point of view of electromagnetic theory, to explain the origin of the colors of the bodies around us
Slide text: Isaac Newton, an English physicist and mathematician, while improving telescopes, drew attention to the fact that the image given by the lens is colored around the edges (1643 -1727)
Slide text: I. Newton's experiment Passing through a prism, sunlight was refracted and gave an image on the wall with a rainbow alternation of colors
Slide text: Spectral composition of light Isaac Newton was the first to pay attention to the spectral composition of light. The scientist found out that the iridescent strip was formed due to different values of the deflection of rays of different colors, i.e. rays with different wavelengths. This is how Newton discovered the dispersion of light.
Slide text: Rainbow stripe - spectrum from the Latin "spectrum" - vision Every hunter wants to know where the pheasant is sitting
Slide text: Closing the hole with red glass, Newton observed only a red spot on the wall. One color wave - monochromatic
Slide text: Closing the hole with blue glass, Newton observed only a blue spot on the wall Wave of one color - monochromatic
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Slide text: Each color has its own wavelength and frequency
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Slide text: Wavelengths of monochromatic light
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Slide text: I. Newton's experiment Explaining the dispersion of light
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Slide text: Different degrees of refraction are associated with different speeds of propagation of light of different frequencies in a given medium. The dependence of the refractive index of light on the oscillation frequency (or wavelength) is called dispersion. Due to the different degree of refraction of different monochromatic colors, a beam of white light is decomposed by a prism into a spectrum.
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Slide text: Synthesis of white light using prisms Having collected the colored beams that came out of the prism with a lens, Newton received a white image of a hole on a white screen instead of a colored strip
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Slide text: Conclusions from Newton's experiments: a prism does not change light, but only decomposes it into its constituent parts; white light as an electromagnetic wave consists of seven monochromatic waves; light beams that differ in color differ in the degree of refraction; violet rays are most strongly refracted, red ones are less than others; red light has the highest speed in the medium, and violet - the smallest, so the prism decomposes the light.
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Slide text: Dispersion explains many natural phenomena: Rainbow Colors of opaque bodies Colors of transparent bodies Game of precious stones
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Slide text: Rainbow A rainbow is a spectrum of sunlight It is formed by the decomposition of white light in raindrops Wide multi-colored beams of light come out of raindrops at different angles of refraction An observer, being outside the rain zone, sees a rainbow against the background of clouds illuminated by the sun, at a distance of 1 - 2 km Conditions for the appearance of a rainbow: 1. A rainbow appears only when the sun peeks out from behind the clouds and only in the direction opposite to the sun. 2. A rainbow occurs when the sun illuminates a curtain of rain. 3. A rainbow appears provided that the angular height of the sun above the horizon does not exceed 42º
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Slide text: Optical phenomena occur in a water drop: Light refraction Light dispersion Light reflection
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Slide text: The color of opaque objects The variety of colors and shades in the world around us explains the phenomenon of dispersion. When interacting with different bodies, rays of light of different colors are reflected and absorbed by these bodies in different ways. Bodies painted white reflect rays of light of different frequencies equally well. Bodies painted black absorb light rays of different frequencies equally well. Opaque bodies are painted in the color whose rays of light they reflect well.
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Slide text: Color of transparent bodies The color of a transparent body is determined by the composition of the light that passes through it. If a transparent body uniformly absorbs the rays of all colors, then in transmitted white light it is colorless, and in colored light it has the color of those rays with which it is illuminated. When white light is passed through tinted glass, it lets through the color it is painted with. This property is used in various light filters.
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Slide text: The game of precious stones The phenomenon of dispersion during repeated refraction of light explains the game of precious stones. Precious stones seem to us to be colored, since the impurities contained in them absorb some components of white light
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Slide text: Conclusions: Dispersion is the phenomenon of decomposition of white light into a spectrum White light is complex, consisting of seven monochromatic colors. The refractive index of a medium depends on the color of light. Light with different wavelengths propagates in a medium at different speeds: violet at the lowest, red at the highest
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Slide text: Consolidation of the studied material "Traffic Light" Using the colored circles, select the correct answer.
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Slide text: 1. What is the name of the dependence of the refractive index on the oscillation frequency or wavelength? Dispersion Interference Diffraction Test yourself
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Slide text: 2. A light beam of small cross section was directed to the prism. The light beam is refracted by the prism and falls on the screen. What picture will be observed on the screen? Dark spot Light spot Spectrum Test yourself
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Slide text: 3. What can be said about the speed of propagation of electromagnetic waves of different frequencies in a vacuum? Red light has the highest speed Purple has the slowest speed Electromagnetic waves travel in a vacuum at the same speed of 300,000 km/s Test yourself
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Slide text: 4. Observation of the hyacinth macaw is carried out in white light, through red and blue light filters. What is the best way to see a bird? Through a red light filter Through a blue light filter In white light Test yourself
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Slide text: 5. What physical phenomenon underlies the formation of a rainbow? Interference Dispersion Diffraction Test yourself
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Slide text: Explain the result of the experiment with the spectral circle
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Slide text: Homework: Textbook § 66 learn Answer questions p. 206 orally Problem solver (Rymkevich) No. 1080 solve
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Slides captions:
dispersion of light.
Newton's experiment on the dispersion of light Newton directed a light beam of small cross section onto a prism. A beam of sunlight entered the darkened room through a small hole in the shutter.
Falling on a glass prism, the light beam was refracted and gave an image with an iridescent alternation of colors on the opposite wall. Newton identified seven colors: Violet Blue Blue Green Yellow Orange Red He called the rainbow stripe spectrum. Newton's experiment on the dispersion of light
Color depends on physical characteristics light wave: oscillation frequency or wavelength. Red light has the longest wavelength and violet light the shortest. Newton's experiment on the dispersion of light
The dependence of the refractive index of light on the oscillation frequency (or wavelength) is called dispersion. Newton made an important conclusion: "Light beams that differ in color differ in the degree of refraction." Newton's experiment on the dispersion of light
The refractive index is determined by the formula: n=c/ υ where c = 300,000 km/s is the speed of light in vacuum u is the speed of a set in a medium If light of different colors is refracted differently, then the speed of monochromatic waves in a substance is different. The refractive index for red light in glass is 1.64 and for violet 1.68. Dispersion and refractive index
Spectroscope and spectrograph O – eyepiece ST – spotting scope P – prism K – collimator Shch – sliding slit
Spectral analysis Emission spectra: 1 – continuous; 2 - sodium; 3 - hydrogen; 4 - helium. Absorption spectra: 5 - solar; 6 - sodium; 7 - hydrogen; 8 - helium.
Links to illustrations: http://im6-tub-ru.yandex.net/i?id=67146028-45-72. http://im4-tub-ru.yandex.net/i?id=46045339-28-72 . http://im4-tub-ru.yandex.net/i?id=289692535-28-72 . http://im5-tub-ru.yandex.net/i?id=344390577-21-72 . http://im7-tub-ru.yandex.net/i?id=496547705-61-72 . http://de.trinixy.ru/pics4/20110525/podb/12/amazing_nature_pics_17.jpg ; http://yro.narod.ru/bibliotheca/Icons/Ikoni/raduga.jpg ; http://www.eaas.co.uk/images/atmospheric_optics/rainbow.jpg ; http://im2-tub-ru.yandex.net/i?id=945671994-10-72 ; http://www.olympusmicro.com/primer/images/diffraction/rainbow.jpg . http://im8-tub-ru.yandex.net/i?id=139297492-17-72 ; http://im4-tub-ru.yandex.net/i?id=191916602-12-72 . http://im2-tub-ru.yandex.net/i?id=337964418-03-72 .
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