“Electromagnetic field” - What happens next? A magnet lying on a table creates only a magnetic field. Causes of electromagnetic waves. A varying magnetic field will create a varying electric field. An electromagnetic field disturbance will occur. Let's imagine a conductor through which electric current flows. Properties of electromagnetic waves:
“Electromagnetic waves lesson” - Electromagnetic nature. What type of radiation do electromagnetic waves with a length of 0.1 mm belong to? Similarities. What type of radiation has the greatest penetrating power? Sources. Differences. Visible light. Wave properties. 1.Radio radiation 2.X-ray 3.Ultraviolet and X-ray 4.Radio radiation and infrared.
“Electromagnetic waves” - Infrared radiation is produced by all bodies at any temperature. B. Electromagnetic waves of different frequencies are different from each other. Questions for consolidation. Emitted at high electron accelerations. Radio waves. An electromagnetic wave is transverse. The nature of the electromagnetic wave.
“Electromagnetic radiation” - Bloodworms that were in a normal environment. A bloodworm that was exposed to mobile phone radiation for two days. The influence of electromagnetic waves on a living organism. Recommendations: Reduce the time spent communicating on a mobile phone. Conclusions and recommendations. Theory of electromagnetic radiation. Keep the phone at a distance of 4 cm from the body.
"Electromagnetic oscillations" - Amplitude -. Number of oscillations per 1s. Phase-magnitude, Equation q=q(t) has the form: A. q= 0.001sin 500t B. q= 0.0001 cos500t C. q= 100sin500t. 100v. The amplitude of charge oscillations on the capacitor is 100 μC. The stage of generalization and systematization of the material. Introduction. Frequency-. Distance from the pendulum to the equilibrium position.
“Electromagnetic waves” - Conditions for maximum and minimum interference. Electromagnetic waves propagate in space, moving away from the vibrator in all directions. Mutually perpendicular, because in 1885 - 89. – Professor at the Higher Technical School in Karlsruhe. 4.2 Differential equation of EMW. Approximately wavelengths fit into one train. A complete analogy of the refraction and reflection of electromagnetic waves with light waves has been established.
There are a total of 14 presentations in the topic
Newton's circle of colors from Optics (1704), showing the relationship between colors and musical notes. The colors of the spectrum from red to violet are separated by notes, starting with D (D). The circle is a full octave. Newton placed the red and violet ends of the spectrum next to each other, emphasizing that the mixture of red and violet produces purple.
The first explanations of the spectrum of visible radiation were given by Isaac Newton in his book “Optics” and Johann Goethe in his work “The Theory of Colors,” but even before them, Roger Bacon observed the optical spectrum in a glass of water. Only four centuries after this, Newton discovered the dispersion of light in prisms. Newton was the first to use the word spectrum (Latin spectrum - vision, appearance) in print in 1671, describing his optical experiments. He made the observation that when a ray of light hits the surface of a glass prism at an angle to the surface, some of the light is reflected and some passes through the glass, forming multi-colored stripes. The scientist suggested that light consists of a stream of particles (corpuscles) of different colors, and that particles of different colors move at different speeds in a transparent medium. According to his assumption, red light moved faster than violet, and therefore the red beam was not deflected by the prism as much as the violet one. Because of this, the visible spectrum of colors arose. Newton divided light into seven colors: red, orange, yellow, green, blue, indigo and violet. He chose the number seven because of his belief (derived from the ancient Greek sophists) that there was a connection between colors, musical notes, objects in the solar system and days of the week. The human eye is relatively sensitive to indigo frequencies, so some people cannot distinguish it from blue or violet. Therefore, after Newton, it was often proposed that indigo should not be considered an independent color, but only a shade of violet or blue (however, it is still included in the spectrum in the Western tradition). In the Russian tradition, indigo corresponds to the color blue. Goethe, unlike Newton, believed that the spectrum arises from the superposition of different components of light. Observing wide beams of light, he discovered that when passing through a prism, red-yellow and blue edges appear at the edges of the beam, between which the light remains white, and a spectrum appears if these edges are brought close enough to each other. In the 19th century, with the discovery of ultraviolet and infrared radiation, understanding of the visible spectrum became more precise. In the early 19th century, Thomas Young and Hermann von Helmholtz also explored the relationship between the visible light spectrum and color vision. Their theory of color vision correctly assumed that it uses three different types of receptors to determine eye color
Early ideas about light From the Greeks, as well as the Hindus, came the statement that vision is something emanating from the eye and, as it were, feeling objects, but also other theories according to which light is a flow of matter emanating from a visible object. Among these hypotheses, the point of view of Democritus (5th century BC) is closest to modern ideas. He believed that light is a stream of particles with certain physical properties, which do not include color (the sensation of color arises as a consequence of the entry of light into the eye). He wrote: “Sweetness exists as a convention, bitterness as a convention, color as a convention, in reality there are only atoms and emptiness.” Later, Platonists gave a very complex explanation of the essence of vision, based on the hypothesis of three streams of particles emanating from the Sun, the object and the eye, merging together and returning to the eye.
Early ideas about light In the Middle Ages, with the revival of science in Europe, it was realized that physical phenomena could only be properly explained by fully studying what was happening, and this new spirit of science aroused special interest in optical experiments. We owe Descartes the concept of “luminiferous ether” (1637) - an infinitely elastic medium that fills all space and transmits light as a kind of pressure. In 1666, I. Newton began an experimental study of the nature of color. He created color theory in the form in which it exists to this day. According to his theory, white color is a mixture of all colors, and objects appear colored because they reflect some components of white color more intensely than others into the observer's eye.
Wave theory Only at the beginning of the 19th century, T. Young in England and O. Fresnel in France created a detailed wave theory of light, capable of answering Newton’s objections, as well as simply and convincingly explaining almost all optical phenomena known at that time. The mathematical wave theory of Fresnel and his sequences underlies modern theoretical optics, although it is simply a theory of wave motion. The origins of another way of searching for the nature of light lay in the discovery of J. Maxwell, made in 1861, that light phenomena are associated with electricity and magnetism. At first, Maxwell considered the ether as a complex mechanical system, the action of which is manifested in electrical and magnetic forces, but is subject to the laws of mechanics.
Quantum theory Einstein's theory of relativity appeared in 1905 and in a surprisingly short time, given its radical nature, won universal recognition. This was partly because the theory of relativity, through its deep connection with experimental facts, demonstrated that the theory of the ether should be discarded. Although Einstein's theory did not provide an answer to the fundamental question of how light propagates, leaving the problem almost in the same form as in the time of Jung and Fresnel, it knocked the ground out from under various kinds of theories of the ether, proving that for this question there is no mechanical solution. Light is a wave, but not a mechanical one, until energy is exchanged with matter. The transition of energy from light to matter or from matter to light obeys the relation E = hν.
Spectrum The spectrum of electromagnetic radiation, a set of monochromatic waves ordered by length into which light or other electromagnetic radiation is decomposed. A typical example of a spectrum is the well-known rainbow. The possibility of decomposing light into a continuous sequence of rays of different colors was first experimentally demonstrated by I. Newton.
Wavelength Range The visible region covers the wavelength range from 400 nm (violet edge) to 760 nm (red edge), which is a tiny part of the full electromagnetic spectrum. The sources in laboratories are red-hot solids, electric discharge and laser. Receivers of visible light are the human eye, photographic plates, photocells, and photomultipliers.
Literature: G. S. Landsberg Optics. M., 1976 T. Brill Light: Impact on works of art. M., 1982 L. A. Apresyan, Yu. A. Kravtsov Theory of radiation transfer. M., 1983 M. A. Elyashevich Atomic and molecular spectroscopy M., 1962 I. I. Sobelman Introduction to the theory of atomic spectra M., 1964
Visible light. Occur in the frequency range 3.85?1014 – 7.89?1014 Hz; Wavelengths lie in the range 380?10-9 - 780?10-9m; The source of visible light is valence electrons in atoms and molecules, changing their position in space, as well as free charges moving at an accelerated rate.
Slide 7 from the presentation "Types of electromagnetic waves". The size of the archive with the presentation is 174 KB.Physics 11th grade
summary of other presentations“Radio waves and frequencies” - Reflective layers of the ionosphere. Possibility of directed radiation of waves. Radio waves and frequencies. The ability to bend around bodies. Short waves. Spectrum distribution. How radio waves propagate. Radio waves. What are radio waves? Mathematician Oliver Heaviside.
“Sounds around us” - Physics around us. Musical sounds. Bell. Musical instruments. The lowest musical sound audible to humans. We listen to music willingly. Organ. Ultrasound. Bottom note. Infrasounds in art. The beauty of formulas. Sounds coming from vibrating strings. Piano. Sounds of different instruments. The difference between music and noise.
“Ampere's force” - How will the Ampere's force acting on a straight conductor with current in a uniform magnetic field change when the current in the conductor decreases by 2 times? Application of Ampere force. Direction in space, which is determined by the left-hand rule. Maxwell called Ampere the "Newton of electricity." Determine the position of the poles of the magnet creating the magnetic field. Ampere power. Using the left-hand rule, determine the direction of the force with which the magnetic field will act on the current-carrying conductor.
“Mechanical waves” physics 11th grade” - A little from history. Characteristics of sound waves. This is interesting. Echo. Types of waves. Mechanism of sound propagation. Sound. A wave is an oscillation propagating in space. The meaning of sound. Mechanical waves. Bats sing songs while flying. Sound wave receivers. What is sound? Sound waves in various media. Type of sound waves. Wave propagation in elastic media. Physical characteristics of the wave.
““Structure of the atom” 11th grade” - Specific ideas about the structure of the atom developed as physics accumulated facts about the properties of matter. Thomson's model of the structure of the atom. Conclusions from experiments. Target. Based on conclusions from experiments, Rutherford proposed a planetary model of the atom. An attempt to save the planetary model of the atom was the postulates of Niels Bohr. Deviation is possible only when encountering a positively charged particle of large mass.
“The phenomenon of interference” - Wave optics. Light waves. Newton's rings. Newton's rings in green and red light. Distance between interference fringes. Repetition of covered material. Study of interference phenomena. Interferometers. Enlightening optics. Distance between slots. Accurate wavelength measurements. Thomas Young. Condition for coherence of light waves. Beam deflection angle. Diffraction grating. Diffraction of light.
Visible light (daylight, solar, electric) is the only range of electromagnetic waves perceived by the human eye. Light waves occupy a narrow range: 380 – 780 nm.
Light source. The source of light is valence electrons in atoms and molecules, changing their position in space, as well as free charges moving at an accelerated rate. light atom
Radiation of different wavelengths in the visible light range has a physiological effect on the retina of the eye, causing a psychological sensation of color. For example, electromagnetic radiation in the range of 530 – 590 nm causes the sensation of yellow color. Color is one of the obvious properties of light.
How does a visual image arise: light, inverted image of the eyes, optic nerve, representation in the brain
The refraction of light by transparent bodies and the appearance of the rainbow stripe was known long before Newton. True, then they believed that white light was simple. And so, Newton performed a simple experiment: he passed a sunbeam through a glass prism and received a wide band of seven pure colors on the screen - a spectrum. This is how the phenomenon of light dispersion was discovered. Range
Newton's experiment: spectrum quartz prism beam of light
Two most important properties of light Diffraction Interference
Diffraction is a phenomenon in which a round wave beam (ray) passing through an opening is broken into secondary waves
Interference is the phenomenon of mutual influence of light waves. Experiment by T. Young As the slits get closer, the number of interference bands increases.
Wavelength range:
Phrases that help you remember the colors of the spectrum: 1) Every Hunter Wants to Know Where the Pheasant Sits. 2) How Jacques the Beller Once Broke the Lantern with His Head.
Visible light is the source of life on Earth. Visible light plays a huge role in the life of all living things: 1) Photosynthesis is the process of producing chlorophyll in plants under the influence of sunlight
2) Under the influence of light, hormones (bilirubin) are produced, and organisms grow. 3) Daylight helps us understand the world around us. 4) Sunlight carries energy and heat.
Some insects and deep-sea animals can emit light. Natural light sources also include: the Sun and other celestial bodies (Moon), lightning, fire, comets, astronomical phenomena, noble gases that glow under the influence of electric current (neon, krypton). Artificial sources include: electric lamps, candles.
Types of radiation: Thermal radiation Electroluminescence Cathodoluminescence Chemiluminescence Photoluminescence
Thermal radiation is light radiation due to the energy of thermal motion of atoms. Heat sources: incandescent lamp Sun flame
Electroluminescence is the phenomenon of glow of non-electric sources under the influence of electric field discharges. Northern Lights Glow of noble gases (krypton, argon, xenon)
Cathodoluminescence is the glow of solids caused by bombardment of them with electrons. TVs and computer monitors
Chemiluminescence is the emission of light as a result of a chemical reaction. The light source remains cold (rotting remains, fireflies) Deep sea fish Bacteria
Photoluminescence is a property of some substances that emit a glow under the influence of radiation incident on them (fluorescent paints, phosphorus) Fluorescent lamp
