Visible light (daylight, sunlight, 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 are valence electrons in atoms and molecules, which change their position in space, as well as free charges moving at an accelerated rate. light atom
Radiation, which has different wavelengths in the range of visible light, has a physiological effect on the retina of the eye, causing a psychological sensation of color. For example, electromagnetic radiation in the 530 - 590 nm range produces a yellow sensation. Color is one of the obvious properties of light.
How the visual image arises: light inverted image eyes optic nerve imaging in the brain
Refraction of light by transparent bodies and the appearance of a rainbow strip in this case was known long before Newton. True, then it was believed that white light is simple. And so, Newton did a simple experiment: he passed a sunbeam through a glass prism and received on the screen a wide strip of seven pure colors - a spectrum. This is how the phenomenon of DISPERSION of light was discovered. Range
Newton's experiment: spectrum of a quartz prism beam of light
Two Essential Properties of Light Diffraction Interference
Diffraction is a phenomenon in which a circular wave beam (ray) passing through an opening breaks up into secondary waves
Interference is the phenomenon of mutual influence of light waves T. Young's experiment As the slits approach each other, the number of interference fringes increases.
Wavelength range:
Phrases to help remember the colors of the spectrum: 1) Every Hunter Wants to Know Where the Pheasant Sits. 2) How Once Jacques-Bell-Ringer 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 - the process of chlorophyll production in plants under the influence of sunlight
2) Under the influence of light, hormones (bilirubin) are produced, organisms grow. 3) Daylight helps us learn about the world around us. 4) Sunlight carries energy and heat.
Some insects and deep sea animals can emit light. Natural sources of light also include: the Sun and other celestial bodies (Moon), lightning, fire, comets, astronomical phenomena, noble gases that glow under the action of an 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 the 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 the bombardment of them with electrons. TVs and computer monitors
Chemiluminescence is the emission of light as a result of a chemical reaction. Light source remains cold (rotting debris, fireflies) Deep sea fish Bacteria
Photoluminescence is a property of certain substances that emit a glow under the influence of incident radiation (fluorescent paints, phosphorus) Daylight lamp
Newton's circle of colors from the book "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 magenta is formed from mixing red and violet colors.
The first explanations of the spectrum of visible radiation were given by Isaac Newton in the book "Optics" and by Johann Goethe in the work "The Theory of Flowers", but even before them Roger Bacon observed the optical spectrum in a glass of water. Only four centuries later, 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 beam of light hits the surface of a glass prism at an angle to the surface, part of the light is reflected, and part of it 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 him, red light moved faster than violet, and therefore the red ray was deflected on the prism not as much as violet. 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 from the belief (derived from the ancient Greek sophists) that there is a connection between colors, musical notes, objects in the solar system and the days of the week. The human eye is relatively weakly sensitive to the frequencies of the indigo color, so some people cannot distinguish it from blue or purple. Therefore, after Newton, it was often proposed to consider indigo not as an independent color, but only as 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 blue. Goethe, in contrast to Newton, believed that the spectrum arises from the superposition of different components of the world. Observing wide beams of light, he found 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 the spectrum appears when these edges are brought close enough to each other. In the 19th century, with the discovery of ultraviolet and infrared radiation, the understanding of the visible spectrum became more accurate. In the early 19th century, Thomas Jung and Hermann von Helmholtz also investigated the relationship between the visible spectrum and color vision. Their theory of color vision correctly assumed that it uses three different types of receptors to determine eye color.
Visible light. They arise in the frequency range 3.85 × 1014 - 7.89 × 1014 Hz; The wavelengths are in the range 380 × 10-9 - 780 × 10-9m; The source of visible light are valence electrons in atoms and molecules, which change their position in space, as well as free charges moving at an accelerated rate.
Slide 7 from presentation "Types of electromagnetic waves"... The size of the archive with the presentation is 174 KB.Physics grade 11
summaries of other presentations"Radio waves and frequencies" - Reflective layers of the ionosphere. Possibility of directed wave emission. Radio waves and frequencies. The ability to bend around the body. Short waves. Spectrum distribution. How radio waves propagate. Radio frequency waves. What are radio waves. Mathematician Oliver Heaviside.
"Sounds around us" - Physics around us. Musical sounds. Bell. Musical instruments. The lowest musical sound heard by man. 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 force" - How will the ampere 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 the 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 that creates the magnetic field. Ampere force. Applying 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 grade 11 "- A bit of history. Characteristics of sound waves. It is interesting. Echo. Types of waves. Sound propagation mechanism. Sound. A wave is vibrations that propagate through space. The meaning of the sound. Mechanical waves. During the flight, the bats sing songs. Sound wave receivers. What is sound. Sound waves in various environments. The type of sound waves. Wave propagation in elastic media. Physical characteristics of the wave.
"" The structure of the atom "Grade 11" - Concrete ideas about the structure of the atom developed as physics accumulated facts about the properties of matter. Thomson's atomic structure model. Conclusions from the experiments. Target. Based on the conclusions from the experiments, Rutherford proposed a planetary model of the atom. The postulates of Niels Bohr became an attempt to save the planetary model of the atom. Deviation is possible only when it encounters 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 fringes. Repetition of the passed material. Study of interference phenomena. Interferometers. Enlightenment of optics. The distance between the slots. Accurate wavelength measurements. Thomas Jung. Coherence condition for light waves. Beam deflection angle. Diffraction grating. Light diffraction.
Early concepts of light From the Greeks, as well as the Hindus, the assertion that vision is something emanating from the eye and, as it were, touching objects, but also other theories, according to which light is a stream of matter emanating from a visible object, came down. Among these hypotheses, the point of view of Democritus (5th century BC) is closest to modern concepts. 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 result 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, the Platonists gave a very complex explanation of the essence of vision, based on the hypothesis of three streams of particles emanating from the Sun, an object and an eye, merging together and returning to the eye.
Early concepts of light In the Middle Ages, with the revival of sciences in Europe, the understanding came that it is possible to correctly explain physical phenomena only by fully studying what is 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 the theory of color as it exists to this day. According to his theory, white is a mixture of all colors, and objects appear to be colored because they reflect some components of white into the eye of the observer more intensely than others.
Wave theory Only at the beginning of the 19th century T. Jung in England and O. Fresnel in France created a detailed wave theory of light, capable of answering Newton's objections, and also simply and convincingly explaining almost all optical phenomena known at that time. The mathematical wave theory of Fresnel and its sequences underlies modern theoretical optics, although it is simply a theory of wave motion. At the origins of another way of searching for the nature of light lay the discovery of J. Maxwell, made in 1861 and that light phenomena are associated with electricity and magnetism. At first, the ether was considered by Maxwell as a complex mechanical system, the action of which manifests itself in electrical and magnetic forces, but obeys the laws of mechanics.
Quantum theory Einstein's theory of relativity appeared in 1905 and in a surprisingly short time, given its radical nature, gained universal acceptance. This was partly because the theory of relativity, through its deep connection with experimental facts, demonstrated that the theory of the aether should be discarded. Although Einstein's theory did not answer 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 of all sorts of theories of aether, proving that there is no mechanical solution. Light is a wave, but not mechanical until there is an exchange of energy 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 collection 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 shown by I. Newton.
The wavelength range of the Visible region corresponds to the wavelength range from 400 nm (violet border) to 760 nm (red border), which is a negligible part of the total electromagnetic spectrum. Sources in laboratories are incandescent solids, electrical discharge and laser. The receivers of visible light are the human eye, photographic plates, photocells, photomultipliers.
Literature: GS Landsberg Optics. M., 1976 T. Brill Light: Effects on Works of Art. Moscow, 1982 L. A. Apresyan, Yu. A. Kravtsov Theory of radiation transfer. M., 1983 M. A. Elyashevich Atomic and molecular spectroscopy M., 1962 I. I. Sobel'man Introduction to the theory of atomic spectra M., 1964
"Electromagnetic field" - What will happen next? A magnet lying on the table creates only a magnetic field. The causes of electromagnetic waves. An alternating magnetic field will create an alternating electric field. There will be a disturbance in the electromagnetic field. Imagine a conductor through which an 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 kind 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.Radioradiation and infrared.
"Electromagnetic waves" - Infrared radiation is given by all bodies at any temperature. B. Electromagnetic waves of different frequencies are different from each other. Questions for consolidation. Emitted at high acceleration of electrons. Radio waves. The electromagnetic wave is transverse. The nature of the electromagnetic wave.
"Electromagnetic radiation" - A bloodworm in a normal environment. Bloodworm, which was under the radiation of a mobile phone for two days. The influence of electromagnetic waves on a living organism. Recommendations: Reduce the time of communication on a mobile phone. Conclusions and recommendations. The theory of electromagnetic radiation. Keep the phone 4 cm away from your body.
"Electromagnetic vibrations" - Amplitude -. The number of oscillations in 1 s. Phase-quantity, Equations q = q (t) has the form: A. q = 0.001sin 500t B. q = 0.0001 cos500t B. q = 100sin500t. 100c. The amplitude of the charge fluctuations on the capacitor is 100 μC. The stage of generalization and systematization of the material. Opening speech. Frequency-. Distance from the pendulum to the equilibrium position.
"Electromagnetic waves" - Condition for maximum and minimum interference. EMEs spread in space, moving away from the vibrator in all directions. Mutually perpendicular, since K. In 1885 - 89. - Professor at the Higher Technical School in Karlsruhe. 4.2 Differential equation of EME. Approximately wavelengths fit in one train. A complete analogy of refraction and reflection of EME with light waves has been established.
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