Phenomena of interference and diffraction of waves download presentation. Interference. presentation for a lesson in physics (Grade 11) on the topic. Explanation of "Newton's rings"

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Technology teacher MBOU secondary school No. 16, Novy Urengoy Interior and planning of the kitchen - dining room

What is an interior? The interior is the internal space of the room, which consists in its architectural, artistic and functional design.

Requirements for the interior Ergonomic requirements - the premises should be comfortable for each member of the family. Switches should be arranged at such a height that everyone can use them, the height of hooks on a hanger, shelves in cabinets should correspond to the height of family members, etc. Sanitary and hygienic requirements - cleanliness, comfortable temperature and humidity, good lighting different zones, isolation of the room from external noise. Aesthetic requirements - the interior should be cozy, beautiful. The colors of the walls and furniture should be combined, the decoration and indoor plants should be chosen with taste.

Kitchen planning "Layout" - the division of space into separate parts that have different purposes. To plan a kitchen means to place furniture and equipment in it in accordance with a certain plan.

Kitchen planning Cooking area (working). The main elements of this zone are a sink, a cooker for cooking food and a refrigerator. Also, floor tables with work surfaces for primary processing and cutting of products, wall cabinets for storing kitchen utensils and equipment, an oven. Modern kitchens are equipped microwave oven, dishwasher and air cleaner (hood).

Kitchen planning Dining area (dining room). There is a dining table and chairs here. Additional lighting may be provided above this area.

Designers are involved in creating interiors An interior designer is a specialist in creating new projects of a harmonious environment to improve human living conditions. The profession of an interior designer involves the whole process of interior design, from the layout of the room, lighting, ventilation systems, acoustics, wall decoration, to furniture arrangement, textile design and the installation of navigation signs.

They believe that the layout of the kitchen primarily depends on the size and shape of the room of the future kitchen. But in any case, the arrangement of furniture and equipment should take place according to the principle of a working triangle, which is set by the position of the sink, stove and refrigerator. This is done in order to spend as little time and effort as possible during cooking.

Kitchen layout options Linear kitchen Suitable for a narrow space and takes up little space.

Kitchen layout options Corner kitchen The most popular, used for a square room. In such a kitchen, a dining table is well placed.

Kitchen layout options A parallel kitchen is convenient for housewives who cook a lot, because a large number of work surfaces are organized.

Kitchen layout options A U-shaped kitchen allows you to create a compact working triangle and use the space functionally.

Color scheme and decoration of the kitchen

Household electrical appliances in the kitchen It is impossible to imagine the life of a modern family without household electrical appliances. They make our lives easier and save time.

A household refrigerator is used to store food and cooked food. Refrigerators are of three types: medium-temperature chambers for storing food for several hours or days; low temperature freezers for long-term storage of products; two-chamber refrigerators, including both components. They are most often installed in home kitchens.

Microwave ovens (microwave ovens) with its help, you can quickly heat up food or defrost food.

The dishwasher washes dishes and dries with hot air, while killing all pathogenic microbes

The air purifier (hood) is used to purify the air

Practical work "Creating a kitchen interior" Cut out templates of furniture and kitchen equipment from a sheet of paper, made in a scale of 1:20. Draw in workbook on the same scale plan your kitchen. By moving the templates on the kitchen plan, perform a rational layout of the kitchen, taking into account the principle of the working triangle. Glue the templates to the plan with glue. Draw a working triangle with a colored felt-tip pen using a ruler. Evaluate the resulting layout.

Consolidation of the material covered 1. Why is it necessary to place equipment according to the principle of a working triangle when planning a kitchen? 2. What type of layout is chosen for your home kitchen? 3. Why does planning need to be done on paper?

A thin film is applied to the surface of the glass

coated optics

The reflection of light for the extreme parts of the spectrum - red and violet - will be less. The lens has a lilac tint.

Deviation of the direction of wave propagation from a rectilinear one at the boundary of the obstacle (envelopment of obstacles by waves)
Condition: the size of the obstacle should be comparable to the wavelength

The Grimaldi Experience

In the middle of the 17th century, the Italian scientist Francesca Maria Grimaldi observed strange shadows from small objects placed in a very narrow beam of light. To the scientist's surprise, these shadows did not have sharp borders, but for some reason were bordered by colored stripes.

Observation conditions

- the size of the obstacle must be commensurate with the wavelength of light
- the distance from the obstacle to the observation point must be much greater than the size of the obstacle

As a result of diffraction, light waves coming from different points are superimposed (coherent waves), and one observes interference waves

Diffraction manifests itself in violation of the straightness of the propagation of light!

Huygens principle Fresnel

Each point of the wave front is a source of secondary waves, and all secondary sources are coherent.

Fresnel proved the rectilinearity of light propagation and considered quantitatively diffraction by various kinds of obstacles.

Peculiarities

diffraction pattern

Explanation

Slit image dimensions

more sizes

obtained through

geometric

constructions

Secondary waves come over

slit edges

Peculiarities

diffraction pattern

Explanation

In the center of the picture appears

light streak

Secondary waves in

direction,

perpendicular to the slot

have the same

phase. Therefore, when they

overlay amplitude

fluctuation increases

Features of the diffraction

Explanation

Along the edges of the picture - alternation

light and dark stripes

Secondary waves interfere

in a direction at an angle to

perpendicular to the slot

having some phase difference, from

which the resulting

oscillation amplitude

Diffraction does not make it possible to obtain distinct images of small objects, as light bends around objects.
Images are blurry. This occurs when the linear dimensions of objects are less than the wavelength of light.

Resolution of the microscope and telescope

If two stars are at a small angular distance from each other, then these rings are superimposed on each other, and the eye cannot distinguish whether there are two luminous points or one.

Wave properties of light: interference, diffraction, polarization Light waves are considered by their nature as electromagnetic waves, which have all their properties. Wave optics is a branch of optics that explains optical phenomena based on the wave nature of light. Wave optics describes such optical phenomena as interference, diffraction, polarization, and dispersion.

Light interference Electromagnetic waves, like mechanical waves, have the principle of superposition, that is, if several waves simultaneously propagate in a medium, then they propagate independently of each other. However, in those places where some fluctuations are superimposed on other fluctuations, their amplitudes add up vectorially. In this case, both an increase in the intensity of light (when waves with identical phases are superimposed) and a decrease in intensity (when waves with opposite phases are added) can be observed. This phenomenon is called light interference. Light interference is the addition of two or more waves, as a result of which a stable pattern of amplification and attenuation of light vibrations at different points in space is observed. Only coherent waves can interfere, that is, waves that have the same frequency and a phase difference that is constant in time. There are no coherent sources in nature, but they can be obtained in different ways. One of them is shown in the picture. It is shown here how, using a screen E 1 with two narrow slits, two coherent ones are obtained from one light source S. The interference pattern in the form of alternating light and dark stripes is observed on the E 2 screen.

Interference patterns can be observed on thin oil films on the water surface, soap bubbles, dragonfly wings, tint colors on the metal surface after heating. The phenomenon of interference in thin films is used to determine the wavelengths of radiation from light sources, to control the quality of polished surface processing, to determine the expansion coefficient of bodies when heated, etc. There are special devices - interferometers designed to measure the lengths of bodies, refractive indices with great accuracy .

Diffraction of light Diffraction is the ability of waves to bend around obstacles encountered in their path, to deviate from rectilinear propagation. To observe the diffraction of light waves, certain conditions are necessary: either the dimensions of the obstacles (or holes) must be very small, or the distance from the obstacle to the observed pattern must be large. Let's take on the path of rays from a point source of light S, put up a barrier with a very small hole of diameter d, then on the screen E we will see a system of alternating light and dark rings (provided that d

Diffraction patterns are often observed in natural conditions. For example, colored rings surrounding a light source viewed through fog or fogged window glass, or when viewing a bright source through eyelashes. To observe diffraction, special instruments are used - diffraction gratings. A diffraction grating (one-dimensional) is a system of parallel equally spaced slits of equal width. The simplest diffraction grating can be made from a glass plate on which parallel scratches are applied with a diamond cutter with intact gaps between them (slits). The distance between adjacent slots is called the period or lattice constant d (Fig.).

where a is the distance between adjacent slots, b is the slot width. The path difference Δ of the rays falling at an arbitrary point P from two adjacent slots will be:

Obviously, oscillations at the point P will reinforce the other if the phase difference of the beams is equal to 0 or differs by 2π, which corresponds to: where k = 0, 1, 2, 3. . . Then the condition for observing the maxima (amplification of oscillations) of light will be: where k = 0, 1, 2, 3. . . Due to diffraction, an uneven redistribution of light energy between the maxima occurs. The diffraction grating is a spectral device. With its help, you can determine the wavelengths in the emission spectra of sources (for example, stars):

Polarization of light As shown above, the light emitted by most sources is a superposition of a huge number of waves emitted by individual atoms. Since the atoms radiate independently of each other, the spatial orientation of the vectors E of the waves of different atoms is arbitrary. Such light is called natural (Fig. a) A beam in which the oscillations of the vector E occur in only one direction (have polarity) is called plane-polarized (or linearly polarized) (Fig. b). The plane in which the vector E oscillates is called the plane of oscillation. The plane in which the vector H (or B) oscillates is called the plane of polarization. The angle between these planes is 900. Natural light can be turned into polarized using devices called polarizers. When natural light falls on the interface between media with different refractive indices, the reflected and refracted beams are always polarized.

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Interference of mechanical waves and light. Physics teacher S.V. Gavrilova

Wave optics Wave optics is a branch of optics in which light is treated as an electromagnetic wave.

Review What do you know about electromagnetic waves? Electromagnetic field propagating in space. The speed in a vacuum is the greatest.

Review List the properties of electromagnetic waves. reflected; The law of rectilinear propagation is fulfilled; Refracted, reflected, absorbed; Plane polarized; Interference and diffraction;

interference of Mechanical waves of Light Sound

Waves that have the same frequency and constant phase difference are called coherent.

The phenomenon of interference is possible if Superimposition of coherent waves Coherent waves Amplification or weakening of waves in space The time-constant phenomenon of mutual amplification and attenuation of oscillations at different points in the medium as a result of superposition of coherent waves is called interference. Interference conditions

Conditions for interference maxima and minima Maximum condition A bright band is observed d 2 , d 1 geometric path of the rays; d=d 2 -d 1 geometric path difference - the difference in distances from the wave sources to the point of their interference; Δ d = d∙n - optical path difference - geometric path difference multiplied by the relative refractive index of the medium. Maximum condition Condition max - the amplitude of oscillations of particles of the medium at a given point is maximum if the difference between the paths of two waves that excite oscillations at a given point is equal to an integer number of wavelengths.

Conditions for interference maxima and minima Minimum condition Minimum condition A dark band is observed Condition min - the amplitude of oscillations of particles of the medium at a given point is minimal if the path difference of two waves that excite oscillations at this point is equal to an odd number of half-wavelengths

Energy distribution during interference Waves carry energy During interference, energy is redistributed Concentrated at maxima, does not enter minima

The history of the discovery of light interference The phenomenon of light interference was discovered in 1802, when the Englishman T. Jung, a physician, astronomer and orientalist, a man with very diverse interests, conducted the now classic "experiment with two holes." June 13, 1773 - May 10, 1829

Light interference Light waves from various sources(except laser) are incoherent Coherence is achieved by dividing light from one source into parts. Light interference is the phenomenon of superposition of light beams, as a result of which a pattern of alternating light and dark stripes is formed.

Jung's classic experience “I made a small hole in the window shutter and covered it with a piece of thick paper, which I pierced with a thin needle. In the path of a sunbeam I placed a strip of paper about one-thirtieth of an inch wide and observed its shadow either on the wall or on a moving screen. Next to the colored stripes on each edge of the shadow, the shadow itself was divided by identical parallel stripes of small sizes, the number of stripes depended on the distance at which the shadow was observed, the center of the shadow always remained white. These stripes were the result of the connection of parts of the light beam that passed on both sides of the strip and inflected, rather diffracted, into the shadow region. T. Jung proved the correctness of this explanation by eliminating one of the two parts of the beam. The interference fringes disappeared, although the diffraction fringes remained. This experience clearly proved that light is not a stream of particles, as was thought since the time of Newton, but a wave. Only waves, forming in different ways, are capable of both amplifying and canceling each other - to interfere.

Interference pattern: alternating light and dark fringes Classical Young's experiment Waves interfere in the overlap region Condition max: Condition min: d- optical path difference - wavelength

color Wavelength, nm Frequency, THz red 760-620 385-487 orange 620-585 484-508 yellow 585-575 508-536 green 575-510 536-600 blue 510-480 600-625 blue 480-450 625- 667 Violet 450-380 667-789 By studying interference fringes, Jung was the first to determine the length and frequency of light waves of different colors. Modern meanings given in the table.

With the help of his theory of interference, Jung was able to explain for the first time a well-known phenomenon - the multi-colored coloring of thin films (oil films on water, bubble, dragonfly wings...)

Interference in thin films Coherent light waves reflected from the top and bottom surfaces interfere. the film thickness is not the same and the interference maxima for waves of different lengths are observed in different places of the film

Newton's rings. Waves 1 and 2 are coherent. Wave 1 is reflected from the glass-air interface Wave 2 is reflected from the air-glass interface The interference pattern occurs in the air gap between the glass plates

Thanks for your attention D.Z. §67-69

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