Presentation on the topic Emiliy Khristianovich Lenz. Lenz's rule presentation for a physics lesson (grade 11) on the topic
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Course work Lenz's rule. The phenomenon of self-induction. The work was performed by Galina Alekseevna Romanova, physics teacher, Secondary School No. 2, Vyazma, 2011.
Goal: learn to determine the direction of the induction current; Using the example of Lenz’s rule, formulate an idea of the fundamental nature of the ESA; explain the essence of the phenomenon of self-induction; derive a formula for calculating the energy of the magnetic field, find out the physical meaning of this formula.
Faraday's experiment: the direction of deflection of the ammeter needle (and, therefore, the direction of the current) can be different.
What is the phenomenon of EMR? If the current strength is changed in a circuit containing a closed circuit (coil), then an induced current will also arise in the circuit itself. This current will also obey Lenz's rule.
Demonstration of the phenomenon of electromagnetic induction
Lenz's experiment If you bring a magnet closer to a conducting ring, it will begin to be repelled from the magnet. This repulsion can only be explained by the fact that an induced current arises in the ring, caused by an increase in the magnetic flux through the ring, and the ring with the current interacts with the magnet.
Demonstration of Lenz's experience
If the magnetic flux through the circuit increases, then the direction of the induced current in the circuit is such that the magnetic induction vector of the field created by this current is directed opposite to the magnetic induction vector of the external magnetic field. If the magnetic flux through the circuit decreases, then the direction of the induced current is such that the vector of the magnetic induction of the field created by this current is codirectional to the vector of the magnetic induction of the external field.
Lenz's rule: the induced current has such a direction that the magnetic flux it creates always tends to compensate for the change in magnetic flux that caused the current. Lenz's rule is a consequence of the law of conservation of energy.
Magnet hovering over superconducting bowl Magnet falls; an alternating magnetic field arises; a vortex electric field arises; undamped ring currents arise in the superconductor; according to Lenz's rule, the direction of these currents is such that the magnet is repelled from the superconductor; the magnet “floats” above the bowl.
Self-induction phenomenon
SELF-INDUCTION – the appearance of a vortex electric field in a conducting circuit when the current strength in it changes; a special case of electromagnetic induction. Due to self-induction, a closed circuit has “inertia”: the current strength in the circuit containing the coil cannot be changed instantly.
Manifestation of the phenomenon of self-induction Circuit closure When a circuit is closed, the current increases, which causes an increase in the magnetic flux in the coil, an eddy electric field appears directed against the current, i.e., a self-induction emf appears in the coil, preventing the increase in current in the circuit. As a result, L1 lights up later than L2.
Opening the circuit When the electrical circuit is opened, the current decreases, a decrease in the magnetic flux in the coil occurs, an eddy electric field appears, directed like a current, i.e., a self-inductive emf appears in the coil, maintaining the current in the circuit. As a result, L flashes brightly when turned off.
Derivation of the formula for self-inductive emf If a magnetic field is created by a current, then it can be argued that Ф ~ В ~ I, i.e. Ф ~ I or Ф = LI, where L is the inductance of the circuit (or self-inductance coefficient). Then
Physical meaning of inductance Inductance is a physical quantity, numerically equal to the self-induction emf that occurs in the circuit when the current changes by 1 A in 1 s.
The phenomenon of self-induction is especially pronounced in a circuit containing a coil with an iron core, since iron significantly increases the magnetic flux of the coil, and therefore the magnitude of the self-induction emf when it changes.
Consequences of self-induction Due to the phenomenon of self-induction, when circuits containing coils with steel cores (electromagnets, motors, transformers) are opened, a significant self-induction EMF is created and sparking or even an arc discharge may occur.
There is an analogy between the establishment of a current of magnitude I in a circuit and the process of a body gaining speed V 1. The establishment of a current I in a circuit occurs gradually. 2. To achieve current strength I, work must be done. 3. The larger L, the slower I grows. 4. 1. The body reaches speed V gradually. 2. To achieve speed V, work must be done. 3. The larger m, the slower V grows. 4.
Questions for the test work on the topic “EMP phenomenon. Self-induction" 1. Definition of the phenomenon of EMR 2. Lenz's rule 3. Law of EMR (definition, formula) 4. Definition of the phenomenon of self-induction 5. EMF of self-induction (formula) 6. Inductance (definition, formula, unit of measurement) 7. Energy of the magnetic field of the current ( formula)
Resources used 1.L.E.Gendenshtein, Yu.L.Dik.- M.: Mnemosyne, 2009.-272 pp.: ill. 2.OK "1C: School. Physics. Grades 7-11: Library of visual aids.” 3. http://files. shcool – collection . edu.ru 4. http://class-fizika.narod.ru
Thank you for your attention!
Slide 1
Emilius Christianovich Lenz From 1823 to 1826 he took part as a physicist in Kotzebue's trip around the world. In 1829 he took part in the first expedition to Elbrus under the leadership of General Emmanuel. In 1828 he was elected adjunct of the academy, and in 1834 academician.Slide 2
At the same time, he was a professor, and in recent years, the rector of St. Petersburg University. He also taught at the famous German School of St. Peter (1830-1831), at the Main Pedagogical Institute and at the Mikhailovsky Artillery School. His lectures on physics and physical geography were distinguished by remarkable clarity and strict systematicity. His famous manuals on physics (for the gymnasium) and physical geography had the same qualities; Both textbooks went through several editions, but the first of them was especially widespread. The scientific activity of Academician Lenz was just as brilliant and fruitful.
Slide 3
In the history of physics, his scientific works will always be given an honorable place. Many of his scientific studies relate to physical geography (on the temperature and salinity of the sea, on the variability of the level of the Caspian Sea, on the barometric measurement of heights, on the measurement of magnetic inclination and the intensity of the earth's magnetism, etc.). But mainly he worked in the field of electromagnetism. By the way, the works of A. Savelyev are devoted to elucidating the importance of these works: “On the works of Academician Lenz in magnetoelectricity” (St. Petersburg, 1854) and V. Lebedinsky: “Lenz as one of the founders of the science of electromagnetism” (magazine “Electricity” 1895). The most important results of his research are presented in all physics textbooks. Exactly:
Slide 4
Lenz's rule, a rule for determining the direction of the induction current: The induction current arising from the relative movement of the conducting circuit and the source of the magnetic field always has such a direction that its own magnetic flux compensates for changes in the external magnetic flux that caused this current. Formulated in 1833 by E. H. Lenz. If the current increases, then the magnetic flux increases. If the induced current is directed opposite the main current. If the induced current is directed in the same direction as the main current. The induced current is always directed in such a way as to reduce the effect of the cause that causes it. In its general formulation, Lenz's rule states that the induced current is always directed in such a way as to counteract the root cause that caused it.
Slide 5
The Joule-Lenz law is a physical law that provides a quantitative assessment of the thermal effect of electric current. Installed in 1842 by Emilius Lenz. In verbal formulation it sounds as follows: The power of heat released per unit volume of a medium during the flow of electric current is proportional to the product of the electric current density and the electric field value. Mathematically can be expressed in the following form: where w is the power of heat release per unit volume, is the electric density current, is the electric field strength, σ is the conductivity of the medium.
Slide 2
At the same time, he was a professor, and in recent years, the rector of St. Petersburg University. He also taught at the famous German School of St. Peter (1830-1831), at the Main Pedagogical Institute and at the Mikhailovsky Artillery School. His lectures on physics and physical geography were distinguished by remarkable clarity and strict systematicity. His famous manuals on physics (for the gymnasium) and physical geography had the same qualities; Both textbooks went through several editions, but the first of them was especially widespread. The scientific activity of Academician Lenz was just as brilliant and fruitful.
Slide 3
In the history of physics, his scientific works will always be given an honorable place. Many of his scientific studies relate to physical geography (on the temperature and salinity of the sea, on the variability of the level of the Caspian Sea, on the barometric measurement of heights, on the measurement of magnetic inclination and the intensity of the earth's magnetism, etc.). But mainly he worked in the field of electromagnetism. By the way, the works of A. Savelyev are devoted to elucidating the importance of these works: “On the works of Academician Lenz in magnetoelectricity” (St. Petersburg, 1854) and V. Lebedinsky: “Lenz as one of the founders of the science of electromagnetism” (magazine “Electricity” 1895). The most important results of his research are presented in all physics textbooks. Exactly:
Slide 4
Lenz's rule, a rule for determining the direction of the induction current: The induction current arising from the relative movement of the conducting circuit and the source of the magnetic field always has such a direction that its own magnetic flux compensates for changes in the external magnetic flux that caused this current. Formulated in 1833 by E. H. Lenz. If the current increases, then the magnetic flux increases. If the induced current is directed opposite the main current. If the induced current is directed in the same direction as the main current. The induced current is always directed in such a way as to reduce the effect of the cause that causes it. In its general formulation, Lenz's rule states that the induced current is always directed in such a way as to counteract the root cause that caused it.
Slide 5
The Joule-Lenz law is a physical law that provides a quantitative assessment of the thermal effect of electric current. Installed in 1842 by Emilie Lenz. In verbal formulation it sounds as follows: The power of heat released per unit volume of a medium during the flow of electric current is proportional to the product of the electric current density and the electric field value. Mathematically can be expressed in the following form: where w is the power of heat release per unit volume, is the electric density current, is the electric field strength, σ is the conductivity of the medium.
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Presentation on the topic: Lenz
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Emilius Christianovich Lenz (born Heinrich Friedrich Emil Lenz. Born February 12 (24), 1804. Died February 10, 1865, Rome) - famous Russian physicist. From 1823 to 1826 he took part as a physicist in Kotzebue's trip around the world. The results of scientific research of this expedition were published by him in “Memoirs of the St. Petersburg Academy of Sciences” (1831). In 1829 he took part in the first expedition to Elbrus under the leadership of General Emanuel. In 1828 he was elected to the adjunct academy, and in 1834 he became an academician. At the same time, he was a professor, and in recent years, the rector of St. Petersburg University. He also taught at the famous German School of St. Peter (1830-1831), at the Main Pedagogical Institute and at the Mikhailovsky Artillery School. His lectures on physics and physical geography were distinguished by remarkable clarity and strict systematicity. His famous manuals on physics (for the gymnasium) and physical geography had the same qualities; Both textbooks went through several editions, but the first of them was especially widespread. The scientific activity of Academician Lenz was just as brilliant and fruitful.
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Slide description:
In the history of physics, his scientific works will always be given an honorable place. Many of his scientific studies relate to physical geography (on the temperature and salinity of the sea, on the variability of the level of the Caspian Sea, on the barometric measurement of heights, on the measurement of magnetic inclination and the intensity of the earth's magnetism, etc.). But mainly he worked in the field of electromagnetism. By the way, the works of A. Savelyev are devoted to elucidating the importance of these works: “On the works of Academician Lenz in magnetoelectricity” (St. Petersburg, 1854) and V. Lebedinsky: “Lenz as one of the founders of the science of electromagnetism” (magazine “Electricity” 1895). The most important results of his research are presented in all physics textbooks. Namely: the law of induction (“Lenz’s Rule”), according to which the direction of the induction current is always such that it interferes with the action (for example, movement) that causes it (1834). "Joule and Lenz's Law": the amount of heat generated by a current in a conductor is proportional to the square of the current and the resistance of the conductor (1844). Experiments confirming the “Peltier phenomenon”; if you pass a galvanic current through bismuth and antimony rods, soldered at the ends and cooled to 0 °C, you can freeze water poured into a hole near the junction (1838). Experiments on the polarization of electrodes (1847), etc.
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Lenz carried out some of his research together with Parrot (on the compression of bodies), Savelyev (on galvanic polarization) and academician Boris Jacobi (on electromagnets). A list of his memoirs, which were published in the Notes of the Imperial Academy of Sciences and in the journal Poggendorfs Annalen, is placed in the Biographisch-literarisches Handwörterbuch von Poggendorf (I, 1424).
Heinrich Friedrich Emil Lenz or Emilius Christianovich Lenz, as he was later called in St. Petersburg, was born in 1804 in the city of Dorpat (now Tartu). At the age of sixteen he entered the University of Dorpat, but did not finish his studies, since in 1823 he was invited to take part in a round-the-world expedition on the sloop “Enterprise” under the command of Lieutenant-Commander Otto Evstafievich Kotzebue. During the trip, Lenz managed to do a number of important geographical studies, for which, upon his return, he received a doctorate from the University of Heydenburg. After which he began teaching physics at St. Petersburg military schools. A year later, Emilius Lenz was elected adjutant of the St. Petersburg Academy of Sciences, and he accepted the offer to participate in a new expedition, this time to the Caucasus “for magnetic, thermometric, barometric and geognostic observations and research in the vicinity of Elbrus.” Then, together with astronomer Karl Khristoforovich Knorre, director of the Nikolaev Observatory, he made geographical observations on the shores of the Caspian Sea. In 1830, Lenz published the results of his research and a report on the work during the trip. By decision of the academic council, he was appointed extraordinary academician and director of the physics laboratory at the Academy of Sciences. Here he met Boris Semenovich Jacobi. Lenz's work in the field of electricity and magnetism dates back to this time. The commonality of scientific interests brought him closer to Jacobi, linking the scientists with a close friendship for life. They worked side by side in the new, developing field of electrical science. Lenz was, as they would say today, a theoretician. Jacobi was an experimenter and a very inventive person. Together with Jacobi, Lenz established that any magnetoelectric machine that serves to produce electric current can be used as an electric motor. Lenz gets acquainted with the works of Faraday, becomes interested in his experiments, conducts his own experiments, on the basis of which he formulates his famous rule. After convincing experiments, Lenz gave a generalized law of induction. Many of Lenz's achievements were ahead of their time and were forgotten. And half a century later - calling the emerging electrical engineering cornerstones. Lenz's work ethic and diversity of interests are incredible. He was also a geophysicist and oceanographer, a university professor and administrator, taught at many educational institutions, was an academician and continuously carried out scientific work. He wrote several textbooks and manuals, which were very popular and went through more than one edition. At the same time, Lenz never sought profit or profited from his talent. His lectures and textbooks, his scientific work, were distinguished by remarkable clarity and strict systematicity. His experiments were always accurate, the results were repeatedly verified and convincing. He taught at the Naval Cadet Corps, at the Mikhailovsky Artillery School, lectured at the Main Pedagogical Institute and headed the department of physics and physical geography at the Pedagogical University. Young people - students and assistants - crowded around Lenz everywhere. Everyone knew the independence of opinions and actions from external influences. For these character traits, Emilius Khristianovich was often appointed to commissions on various sensitive issues. First elected dean of the Faculty of Physics and Mathematics, he was elected rector of the university in 1863. But he did not stay in this position for long. Having received leave for treatment in 1864, Lenz went abroad and died suddenly in Rome on February 10, 1865. Lenz's school produced remarkable scientists who played a prominent role in the development of physical science. And Emilius Christianovich Lenz himself occupies a prominent place in the history of physics, in the history of science, not only in terms of his scientific results, but also in his moral character, being an example of honest and selfless service to Russia.
