{"id":2593,"date":"2025-03-22T16:01:01","date_gmt":"2025-03-22T16:01:01","guid":{"rendered":"https:\/\/szmz.hu\/teaching\/?page_id=2593"},"modified":"2025-03-22T16:54:42","modified_gmt":"2025-03-22T16:54:42","slug":"mediahistory-on-the-history-of-electricity","status":"publish","type":"page","link":"https:\/\/szmz.hu\/teaching\/media-history\/mediahistory-on-the-history-of-electricity\/","title":{"rendered":"MediaHistory: on the History of Electricity"},"content":{"rendered":"\n<figure class=\"wp-block-embed is-type-video is-provider-youtube wp-block-embed-youtube wp-embed-aspect-16-9 wp-has-aspect-ratio\"><div class=\"wp-block-embed__wrapper\">\n<iframe loading=\"lazy\" title=\"Shock and Awe: The Story of Electricity -- Jim Al-Khalili  BBC Horizon\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/Gtp51eZkwoI?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe>\n<\/div><\/figure>\n\n\n\n<p>It was well known from at least the antiquity that by rubbing certain materials electrical charge can be created, but for several centuries we did&#8217;t have any explanation of this strange phenomena. Systematic experiments with static electricity began not earlier than the 17th century, and became an important subject of entertainers &#8211; called electritians &#8211; by the 18th century.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"571\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Guericke_Sulfur_globe-1024x571.jpg\" alt=\"\" class=\"wp-image-2596\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Guericke_Sulfur_globe-1024x571.jpg 1024w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Guericke_Sulfur_globe-300x167.jpg 300w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Guericke_Sulfur_globe-768x428.jpg 768w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Guericke_Sulfur_globe-1536x857.jpg 1536w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Guericke_Sulfur_globe-2048x1142.jpg 2048w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">Figure V and VI from Ottonis De Guericke Experimenta Nova (ut vocantur) Magdeburgica De Vacuo Spatio, Amstelodami: Janssonius, 1672, p. 148, showing Guericke&#8217;s experiments with the sulfur globe.<br><\/figcaption><\/figure>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-28f84493 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"406\" height=\"649\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Hauksbee_generator.jpg\" alt=\"\" class=\"wp-image-2599\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Hauksbee_generator.jpg 406w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Hauksbee_generator-188x300.jpg 188w\" sizes=\"auto, (max-width: 406px) 100vw, 406px\" \/><figcaption class=\"wp-element-caption\">The great advances in experimenting with electricity came during the 1700s from increased ability to control it. Pictured here (Physico-Mechanical Experiments, 1702) is a device Hauksbee made with a hollow glass sphere that could be mechanically rubbed at high speed, producing larger and more stable charges.<\/figcaption><\/figure>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<figure class=\"wp-block-image alignright size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"672\" height=\"956\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02static2.jpg\" alt=\"\" class=\"wp-image-2602\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02static2.jpg 672w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02static2-211x300.jpg 211w\" sizes=\"auto, (max-width: 672px) 100vw, 672px\" \/><figcaption class=\"wp-element-caption\">In a famous episode, the German experimentalist Georg Richmann, working at the Russian court in St. Petersburg, was killed in 1753 while trying to capture the charge of lightning. This tragedy was widely illustrated in the contemporary press as a story of heroism in the pursuit of science.<br><\/figcaption><\/figure>\n<\/div>\n<\/div>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"708\" height=\"415\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02grayboy.jpg\" alt=\"\" class=\"wp-image-2605\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02grayboy.jpg 708w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02grayboy-300x176.jpg 300w\" sizes=\"auto, (max-width: 708px) 100vw, 708px\" \/><figcaption class=\"wp-element-caption\">This is one of Gray&#8217;s most famous experiments, in which he showed that a boy suspended by (insulating) silk cords could be charged (with the glass tube) and then as a (conducting) body could (electrostatically) attract small objects. Dramatic experiments such as these became quite well-known &#8212; this plate is in fact from a German\u2028publication in 1744 describing Gray&#8217;s work.<\/figcaption><\/figure>\n\n\n\n<p>Experiments by the silk-trader Stephen Gray spread the fashion of static electricity from the 1740s in Europe. Gray discovered that some materials conduct, while others insulate electric current. At that time electric flow was considered similar to the flow of water, with the exception that it was still impossible to store the misterious energy.<\/p>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-28f84493 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"692\" height=\"1024\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02static-692x1024.jpg\" alt=\"\" class=\"wp-image-2608\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02static-692x1024.jpg 692w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02static-203x300.jpg 203w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02static.jpg 703w\" sizes=\"auto, (max-width: 692px) 100vw, 692px\" \/><\/figure>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<figure class=\"wp-block-image alignright size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"668\" height=\"1024\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02nollet-668x1024.jpg\" alt=\"\" class=\"wp-image-2611\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02nollet-668x1024.jpg 668w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02nollet-196x300.jpg 196w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02nollet-768x1178.jpg 768w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02nollet-1001x1536.jpg 1001w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02nollet.jpg 1141w\" sizes=\"auto, (max-width: 668px) 100vw, 668px\" \/><\/figure>\n<\/div>\n<\/div>\n\n\n\n<p>Pieter von Musschenbroek accidentally finds the way to store electrical charge; the Leyden Jar was capable to keep its charge for several days. Despite that conductors and insulators were already at that time, electric charge, electricity became firt transportable by carrying Leyden Jars.<\/p>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"950\" height=\"695\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02leydenjar.gif\" alt=\"\" class=\"wp-image-2614\"\/><figcaption class=\"wp-element-caption\">Besides creating static electricity with friction machines, by 1746 experimentalists learned how to capture and store it. The &#8220;Leyden jar&#8221; was named for the Dutch university where the professor Pieter von Musschenbroek (1692-1761) refined the device. It was a condensor that let one store charge in the water (or conducting foil) in a bottle and then\u2028discharge a powerful spark.<\/figcaption><\/figure>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-28f84493 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" src=\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/5\/5f\/Benjamin_West%2C_English_%28born_America%29_-_Benjamin_Franklin_Drawing_Electricity_from_the_Sky_-_Google_Art_Project.jpg\" alt=\"\"\/><figcaption class=\"wp-element-caption\">Benjamin West: <em>Benjamin Franklin Drawing Electricity from the Sky<\/em>, cca. 1816<\/figcaption><\/figure>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" src=\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/e\/e3\/Benjamin_Franklin_1956_issue_3c.JPG\" alt=\"\"\/><\/figure>\n<\/div>\n<\/div>\n\n\n\n<p>Pieter von Musschenbroek accidentally finds the way to store electrical charge; the Leyden Jar was capable to keep its charge for several days. Despite that conductors and insulators were already at that time, electric charge, electricity became firt transportable by carrying Leyden Jars.<\/p>\n\n\n\n<p>The American Benjamin Franklin proved that thunderbolts are electrical phenomena, thus linking electricity with light. During his experiments with the Leyden jar he discovered the difference between negative and positive charge. He imagined that every conducting body was surrounded by an invisible electric fluid; on the side of positive charge too much electrical fluid is present, while at the negative pole there is a lack of this fluid. And that nature endeavors to balance always (as does the ideal american economy), the two poles attract each other. This is the explanation to why the Leiden bottle is only charged with electricity when you keep it in your hands, which serves as a conductor: the positive charge of the human hand attracts the negative charge, from which the glass of the jar insulates it. This charging negative strain(voltage) cause the electric shock if we touch the conduit on the top of the jar. Contemporary condensators, which is a component of almost every electrical appliance, work exactly the same way, they are the modern miniature versions of the Leyden jar.<\/p>\n\n\n\n<figure class=\"wp-block-embed is-type-video is-provider-youtube wp-block-embed-youtube wp-embed-aspect-16-9 wp-has-aspect-ratio\"><div class=\"wp-block-embed__wrapper\">\n<iframe loading=\"lazy\" title=\"Shock and Awe: The Story of Electricity -- Jim Al-Khalili  BBC Horizon\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/Gtp51eZkwoI?start=1246&#038;feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe>\n<\/div><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"747\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02walshpicture1-1024x747.png\" alt=\"\" class=\"wp-image-2623\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02walshpicture1-1024x747.png 1024w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02walshpicture1-300x219.png 300w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02walshpicture1-768x561.png 768w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02walshpicture1.png 1044w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">Male and female Torpedo. From John Walsh, \u201cOf the Electric Property of the Torpedo,\u201d\u2028Philosophical Transactions 63 (1773): 480.<\/figcaption><\/figure>\n\n\n\n<p>With the introduction of the torpedo fish in England a new type of electricity (fundamentally different from static electricity) was discovered. Henry Cavendish aimed to reproduce the amazingly strong electric shock produced by the torpedo fish, and discovers the difference between voltage(electric tension) and amperage (the intensity of electric current).<\/p>\n\n\n\n<figure class=\"wp-block-embed is-type-video is-provider-youtube wp-block-embed-youtube wp-embed-aspect-16-9 wp-has-aspect-ratio\"><div class=\"wp-block-embed__wrapper\">\n<iframe loading=\"lazy\" title=\"Shock and Awe: The Story of Electricity -- Jim Al-Khalili  BBC Horizon\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/Gtp51eZkwoI?start=1768&#038;feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe>\n<\/div><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"578\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02huntertpicture1-1024x578.png\" alt=\"\" class=\"wp-image-2629\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02huntertpicture1-1024x578.png 1024w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02huntertpicture1-300x169.png 300w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02huntertpicture1-768x433.png 768w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02huntertpicture1.png 1040w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">Cross-section of the Torpedo (displaying electrical organs). From John Hunter, \u201cAnatomical Observations on the Torpedo,\u201d Philosophical Transactions 63 (1773): 489.<\/figcaption><\/figure>\n\n\n\n<p>The fact that living organisms can produce electricity opened a new chapter in investigating the mysterious phenomena. Is this the same electricity what can be produced artificially, which is similar to God&#8217;s whip, to the thunderbolt?<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"614\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02galvani2-1024x614.jpg\" alt=\"\" class=\"wp-image-2632\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02galvani2-1024x614.jpg 1024w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02galvani2-300x180.jpg 300w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02galvani2-768x460.jpg 768w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02galvani2.jpg 1378w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">By the end of the century, there were also tantalizing experimental suggestions that electricity might be the force of life, a Newtonian entity that would explain &#8220;animal spirits&#8221;. Deeply influential were the experimental results of the anatomist Luigi Galvani (1737-98), who reported in 1791 his startling work on the effects of electricity on muscle.<\/figcaption><\/figure>\n\n\n\n<p>In Italy two scientists competed with each other from the distance of 150km, in Bologna and Pavia; the studies of Galvani and Volta were the next important milestones of the history of electricity. Galvani&#8217;s approach came from anatomy\/autopsy, he concentrated on electrical shocking of dead or paralyzed tissues. He was convinced that living organisms are filled with a completely different kind of electricity from the artificially produceable one, that was planted into every living creature by God.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"726\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Experiments_with_buckets_animal_parts_Essai_th_orique_et_exp_rimental_sur_le_galvanisme_1804-1024x726.jpg\" alt=\"\" class=\"wp-image-2635\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Experiments_with_buckets_animal_parts_Essai_th_orique_et_exp_rimental_sur_le_galvanisme_1804-1024x726.jpg 1024w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Experiments_with_buckets_animal_parts_Essai_th_orique_et_exp_rimental_sur_le_galvanisme_1804-300x213.jpg 300w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Experiments_with_buckets_animal_parts_Essai_th_orique_et_exp_rimental_sur_le_galvanisme_1804-768x545.jpg 768w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Experiments_with_buckets_animal_parts_Essai_th_orique_et_exp_rimental_sur_le_galvanisme_1804.jpg 1536w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"749\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Experiments_with_cadavers_and_severed_heads_Essai_th_orique_et_exp_rimental_sur_le_galvanisme_1804-1024x749.jpg\" alt=\"\" class=\"wp-image-2638\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Experiments_with_cadavers_and_severed_heads_Essai_th_orique_et_exp_rimental_sur_le_galvanisme_1804-1024x749.jpg 1024w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Experiments_with_cadavers_and_severed_heads_Essai_th_orique_et_exp_rimental_sur_le_galvanisme_1804-300x219.jpg 300w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Experiments_with_cadavers_and_severed_heads_Essai_th_orique_et_exp_rimental_sur_le_galvanisme_1804-768x562.jpg 768w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Experiments_with_cadavers_and_severed_heads_Essai_th_orique_et_exp_rimental_sur_le_galvanisme_1804.jpg 1536w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"736\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Experiments_with_headless_cadavers_Essai_th_orique_et_exp_rimental_sur_le_galvanisme_1804-1024x736.jpg\" alt=\"\" class=\"wp-image-2641\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Experiments_with_headless_cadavers_Essai_th_orique_et_exp_rimental_sur_le_galvanisme_1804-1024x736.jpg 1024w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Experiments_with_headless_cadavers_Essai_th_orique_et_exp_rimental_sur_le_galvanisme_1804-300x216.jpg 300w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Experiments_with_headless_cadavers_Essai_th_orique_et_exp_rimental_sur_le_galvanisme_1804-768x552.jpg 768w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Experiments_with_headless_cadavers_Essai_th_orique_et_exp_rimental_sur_le_galvanisme_1804.jpg 1536w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">Among the inspirations for Mary Shelley&#8217;s gothic classic &#8216;Frankenstein&#8217; from 1818 were the (in)famous experiments carried out in public by the physicist Giovanni Aldini (1762-1834) at the Royal College of Surgeons in 1803.<br><br>&#8220;In January 1803, the body of the murderer George Forster was pulled from the gallows of Newgate Prison in London and taken to the Royal College of Surgeons. There, before an audience of doctors and curiosity-seekers, Giovanni Aldini, nephew of the late Luigi Galvani, prepared to return the corpse to life.<br><br>At least, that is what some of the spectators thought they were witnessing. When Aldini applied conducting rods, connected to a large battery, to Forster&#8217;s face, &#8220;the jaw began to quiver, the adjoining muscles were horribly contorted, and the left eye actually opened&#8221;. The climax of the performance came as Aldini probed Forster&#8217;s rectum, causing his clenched fist to punch the air, as if in fury, his legs to kick and his back to arch violently.&#8221;<\/figcaption><\/figure>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-28f84493 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"768\" height=\"1024\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02VoltaBattery.jpg\" alt=\"\" class=\"wp-image-2644\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02VoltaBattery.jpg 768w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02VoltaBattery-225x300.jpg 225w\" sizes=\"auto, (max-width: 768px) 100vw, 768px\" \/><\/figure>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"838\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Voltaic_pile.svg_-1024x838.png\" alt=\"\" class=\"wp-image-2647\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Voltaic_pile.svg_-1024x838.png 1024w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Voltaic_pile.svg_-300x245.png 300w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Voltaic_pile.svg_-768x628.png 768w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Voltaic_pile.svg_.png 1252w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n<\/div>\n<\/div>\n\n\n\n<figure class=\"wp-block-embed is-type-video is-provider-youtube wp-block-embed-youtube wp-embed-aspect-4-3 wp-has-aspect-ratio\"><div class=\"wp-block-embed__wrapper\">\n<iframe loading=\"lazy\" title=\"The Voltaic Pile\" width=\"500\" height=\"375\" src=\"https:\/\/www.youtube.com\/embed\/edMN7P5oCaY?start=9&#038;feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe>\n<\/div><\/figure>\n\n\n\n<p>As Volta invented his famous piles, it became possible to examine the phenomenon of electrolysis. The continuous electrical current led to the disintegration of water molecules, caused hydrogen and oxygen precipitation from the water. This started a new chapter in all natural sciences, both in chemistry where new chemical elements could be discovered, but even in physics.<\/p>\n\n\n\n<figure class=\"wp-block-embed is-type-video is-provider-youtube wp-block-embed-youtube wp-embed-aspect-16-9 wp-has-aspect-ratio\"><div class=\"wp-block-embed__wrapper\">\n<iframe loading=\"lazy\" title=\"Water Electrolysis\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/HQ9Fhd7P_HA?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe>\n<\/div><\/figure>\n\n\n\n<p>The following step was the discovery of the relationship between electricity and the magnetic field. In 1820 the Danish Hans Christian \u00d8rsted discovers that the electric flow in wires hijacks the compass. Based on \u00d8rsted&#8217;s discovery Faraday proves the existence of electromagnetic field and electromagnetic induction.<\/p>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"854\" height=\"575\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02iranytu.jpg\" alt=\"\" class=\"wp-image-2650\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02iranytu.jpg 854w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02iranytu-300x202.jpg 300w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02iranytu-768x517.jpg 768w\" sizes=\"auto, (max-width: 854px) 100vw, 854px\" \/><\/figure>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-28f84493 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"400\" height=\"282\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Faradayrotations_01.jpg\" alt=\"\" class=\"wp-image-2653\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Faradayrotations_01.jpg 400w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Faradayrotations_01-300x212.jpg 300w\" sizes=\"auto, (max-width: 400px) 100vw, 400px\" \/><\/figure>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"826\" height=\"625\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Induction_experiment.png\" alt=\"\" class=\"wp-image-2656\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Induction_experiment.png 826w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Induction_experiment-300x227.png 300w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Induction_experiment-768x581.png 768w\" sizes=\"auto, (max-width: 826px) 100vw, 826px\" \/><\/figure>\n<\/div>\n<\/div>\n\n\n\n<p>Faraday essentially created the first electric motor, and the first practical device producing electricity, the Faraday wheel: this homopolar generator was capable to develop electrical current from rotating movement in a magnetic field.<\/p>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-28f84493 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"487\" height=\"382\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Faraday_disk_generator.jpg\" alt=\"\" class=\"wp-image-2659\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Faraday_disk_generator.jpg 487w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Faraday_disk_generator-300x235.jpg 300w\" sizes=\"auto, (max-width: 487px) 100vw, 487px\" \/><\/figure>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<figure class=\"wp-block-image alignright size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"352\" height=\"273\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02ind_disc_01_co.gif\" alt=\"\" class=\"wp-image-2662\"\/><\/figure>\n<\/div>\n<\/div>\n\n\n\n<p>The Faraday disk was the first electric generator (1831). The horseshoe-shaped magnet (A) created a magnetic field through the disk (D). When the disk was turned, this induced an electric current radially outward from the center toward the rim. The current flowed out through the sliding spring contact m, through the external circuit, and back into the center of the disk through the axle.<\/p>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"1005\" height=\"476\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02electromagnet.jpg\" alt=\"\" class=\"wp-image-2665\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02electromagnet.jpg 1005w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02electromagnet-300x142.jpg 300w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02electromagnet-768x364.jpg 768w\" sizes=\"auto, (max-width: 1005px) 100vw, 1005px\" \/><\/figure>\n\n\n\n<p>The coiled electromagnets created by William Sturgeon and Joseph Henry have paved the way for the creation of the first telecommunication medium, the telegraph.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"449\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02transatlantic-1024x449.jpg\" alt=\"\" class=\"wp-image-2668\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02transatlantic-1024x449.jpg 1024w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02transatlantic-300x132.jpg 300w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02transatlantic-768x337.jpg 768w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02transatlantic.jpg 1181w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<p>Following the invention of the light bulb, Edison started to set up an electrical network in Manhattan. The direct current (DC), however, can not be transmitted economically over long distances, so the alternating current (AC, invented by Tesla) networks, based on transformators was the real breakthrough.<\/p>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"1000\" height=\"685\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/menlo-park-facility.jpg\" alt=\"\" class=\"wp-image-2671\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/menlo-park-facility.jpg 1000w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/menlo-park-facility-300x206.jpg 300w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/menlo-park-facility-768x526.jpg 768w\" sizes=\"auto, (max-width: 1000px) 100vw, 1000px\" \/><figcaption class=\"wp-element-caption\">Edison&#8217;s lab in Menlo Park.<\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"677\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02westinghouseAC-1024x677.jpg\" alt=\"\" class=\"wp-image-2674\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02westinghouseAC-1024x677.jpg 1024w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02westinghouseAC-300x198.jpg 300w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02westinghouseAC-768x508.jpg 768w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02westinghouseAC-1536x1015.jpg 1536w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02westinghouseAC-2048x1354.jpg 2048w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<p>Maxwell described mathematically the operation of the electric field, what Heinrich Hertz and Oliver Lodge proved by demonstrative practical experiments, besides laying the foundations of the practical use of electromagnetic (radio) waves. Following Lodge, Jagadish Chandra Bose creates the first telegraph which was stolen by Marconi, who patents it and makes money from it. But Bose discovers the advantages of using semiconductor crystals for the detection of radio waves, so practically invents the radio-receiver.<\/p>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"880\" height=\"591\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Marconi.jpg\" alt=\"\" class=\"wp-image-2677\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Marconi.jpg 880w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Marconi-300x201.jpg 300w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Marconi-768x516.jpg 768w\" sizes=\"auto, (max-width: 880px) 100vw, 880px\" \/><\/figure>\n\n\n\n<p>The ancestors of &#8220;neon-tubes&#8221;, the first vacuum tubes filled with different gases were produced by Johann Heinrich Wilhelm Geissler (1815-1879) from the 1850s. These early cathode-ray tubes were called Geissler-tubes. In these spectacular tubes the contained gases were glowing in various colors as electric current was conducted through them. (Today&#8217;s fluorescent tubes and lightbulbs work pretty the same way &#8211; it is rather surprising that they were invented decades before Edison&#8217;s light bulb.)<\/p>\n\n\n\n<figure class=\"wp-block-image alignwide size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"600\" height=\"346\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02box3.jpg\" alt=\"\" class=\"wp-image-2680\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02box3.jpg 600w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02box3-300x173.jpg 300w\" sizes=\"auto, (max-width: 600px) 100vw, 600px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-image alignwide size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"600\" height=\"338\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02box4.jpg\" alt=\"\" class=\"wp-image-2683\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02box4.jpg 600w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02box4-300x169.jpg 300w\" sizes=\"auto, (max-width: 600px) 100vw, 600px\" \/><figcaption class=\"wp-element-caption\">Sir William Crookes (1832-1919) was able to produce even more perfect wacuum in glass tubes by inventing a pump in 1879, which more efficiently blew out air from them.<\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"768\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02railway_tube1-big-1024x768.jpg\" alt=\"\" class=\"wp-image-2686\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02railway_tube1-big-1024x768.jpg 1024w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02railway_tube1-big-300x225.jpg 300w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02railway_tube1-big-768x576.jpg 768w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02railway_tube1-big-1536x1152.jpg 1536w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02railway_tube1-big-2048x1536.jpg 2048w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">The Railway tube (Crookes nr 11)<br>Demonstrates kinetic energy.\u00a0 The electrons bounced at\u00a0 the paddles covered\u00a0 with a small amount of phosphor will turn\u00a0\u00a0the paddlewheel and move from one to the other side of the tube. In fact it is the heat which is present when the electrons strike the vanes that turns the peddle wheel similar as the Radiometer. Several scientists like Maxwell and Puluj stated this although Crookes was convinced of the electron force theory. Eventually it was Thomson who proved (1903) that the electron force in the tube necessary to move the wheel was insufficient.<\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"817\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02maltese_cross_tube-big.jpg\" alt=\"\" class=\"wp-image-2689\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02maltese_cross_tube-big.jpg 1024w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02maltese_cross_tube-big-300x239.jpg 300w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02maltese_cross_tube-big-768x613.jpg 768w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">The Maltese Cross tube (Crookes nr 9)<br>This is one of the most famous Crookes tubes. The tube demonstrates that electrons go in a straight line and don&#8217;t go through metal. The cross can actually lay down and stand up (mechanically). When the cross lies\u00a0 down, the glass face of the tube emits a green glow when the electrons strike the glass wall, when it&#8217;s right up you will see the shadow of the cross. After a while due to fatigue of the glass the glow is less strong, when the cross is tipped over at that time, the previous unexposed glass glows brighter than the surrounding glass.<\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"768\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02maltesecrossbig-4-1024x768.jpg\" alt=\"\" class=\"wp-image-2692\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02maltesecrossbig-4-1024x768.jpg 1024w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02maltesecrossbig-4-300x225.jpg 300w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02maltesecrossbig-4-768x576.jpg 768w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02maltesecrossbig-4.jpg 1280w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-embed is-type-video is-provider-youtube wp-block-embed-youtube wp-embed-aspect-16-9 wp-has-aspect-ratio\"><div class=\"wp-block-embed__wrapper\">\n<iframe loading=\"lazy\" title=\"Vacuum Tube - Sixty Symbols\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/7NCs7YiFRBU?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe>\n<\/div><\/figure>\n\n\n\n<figure class=\"wp-block-image aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"647\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Crookes_tube_xray_experiment-1024x647.jpg\" alt=\"\" class=\"wp-image-2695\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Crookes_tube_xray_experiment-1024x647.jpg 1024w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Crookes_tube_xray_experiment-300x190.jpg 300w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Crookes_tube_xray_experiment-768x486.jpg 768w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Crookes_tube_xray_experiment.jpg 1161w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">Photo of experimenters taking an X-ray with an early Crookes tube apparatus, from the late 1800s. The Crookes x-ray tube is visible suspended at center. The upper man is examining the bones of his hand with a fluoroscope screen. The lower man is taking a radiograph of his hand with a photographic plate. The power source is an induction coil, seen at left, and the mechanism immediately to its right against the wall is a motor-operated &#8216;break wheel&#8217; interrupter in the coil&#8217;s primary circuit. The large flat disk on the table is a rheostat (adjustable resistor) power control to adjust the primary current to the coil. Several spare Crookes X-ray tubes are seen in a rack on the wall. No precautions against radiation exposure are taken; its hazards were not known at the time.<\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"463\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02braun-tube-big-1024x463.jpg\" alt=\"\" class=\"wp-image-2698\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02braun-tube-big-1024x463.jpg 1024w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02braun-tube-big-300x136.jpg 300w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02braun-tube-big-768x347.jpg 768w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02braun-tube-big-1536x695.jpg 1536w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02braun-tube-big-2048x926.jpg 2048w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">The Braun tube, this small early 1900 tube is in fact a cold Cathode Crookes tube with an internal mica screen covered with phosphorescent paint. The neck contains a glass diaphragm with a small 2mm hole to let only a tiny electron beam go through\u00a0 (focus) which can be deflected by an (electro) magnet to produce a spot on the screen.\u00a0<\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"784\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02wehnelt_crt-big-1024x784.jpg\" alt=\"\" class=\"wp-image-2701\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02wehnelt_crt-big-1024x784.jpg 1024w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02wehnelt_crt-big-300x230.jpg 300w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02wehnelt_crt-big-768x588.jpg 768w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02wehnelt_crt-big-1536x1175.jpg 1536w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02wehnelt_crt-big.jpg 1964w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">Wehnelt CRT after Thomson ca 1930<br>This nice tube is the first demonstration CRT with a direct heated filament cathode and a Wehnelt cylinder for focussing the electron beam.This tube, probably imported from E Leybolds Nachfolger and sold by W Edwards and co London. Special is the fact that this tube has four static deflection plates.\u00a0<\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"419\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Thomson1-big-1024x419.jpg\" alt=\"\" class=\"wp-image-2704\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Thomson1-big-1024x419.jpg 1024w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Thomson1-big-300x123.jpg 300w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Thomson1-big-768x314.jpg 768w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Thomson1-big-1536x629.jpg 1536w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02Thomson1-big-2048x838.jpg 2048w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">This from origin cold cathode Braun tube is equipped with two deflection plates to bent the beam electrostatically instead of magnetically as with the Braun tube. This tube became forerunner of the static CRT used in measuring equipment like the oscilloscope. The neck contains an aluminum diaphragm to form the beam.<\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"576\" src=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02elektroncsovek-1024x576.jpg\" alt=\"\" class=\"wp-image-2707\" srcset=\"https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02elektroncsovek-1024x576.jpg 1024w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02elektroncsovek-300x169.jpg 300w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02elektroncsovek-768x432.jpg 768w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02elektroncsovek-1536x864.jpg 1536w, https:\/\/szmz.hu\/teaching\/wp-content\/uploads\/2025\/03\/02elektroncsovek-2048x1152.jpg 2048w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<p>Transistors, How do they work ?<a href=\"https:\/\/www.youtube.com\/watch?v=7ukDKVHnac4\" target=\"_blank\" rel=\"noreferrer noopener\">https:\/\/www.youtube.com\/watch?v=7ukDKVHnac4<\/a><\/p>\n\n\n\n<p><a href=\"https:\/\/www.youtube.com\/watch?v=ABmDDn8Y1QY\" target=\"_blank\" rel=\"noreferrer noopener\">Hogyan k\u00e9sz\u00fclt? Az audio v\u00e1kuumcs\u00f6vek<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>It was well known from at least the antiquity that by rubbing certain materials electrical charge can be created, but for several centuries we did&#8217;t have any explanation of this strange phenomena. Systematic experiments with static electricity began not earlier than the 17th century, and became an important subject of entertainers &#8211; called electritians &#8211; [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":892,"menu_order":10,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-2593","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/szmz.hu\/teaching\/wp-json\/wp\/v2\/pages\/2593","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/szmz.hu\/teaching\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/szmz.hu\/teaching\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/szmz.hu\/teaching\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/szmz.hu\/teaching\/wp-json\/wp\/v2\/comments?post=2593"}],"version-history":[{"count":3,"href":"https:\/\/szmz.hu\/teaching\/wp-json\/wp\/v2\/pages\/2593\/revisions"}],"predecessor-version":[{"id":2710,"href":"https:\/\/szmz.hu\/teaching\/wp-json\/wp\/v2\/pages\/2593\/revisions\/2710"}],"up":[{"embeddable":true,"href":"https:\/\/szmz.hu\/teaching\/wp-json\/wp\/v2\/pages\/892"}],"wp:attachment":[{"href":"https:\/\/szmz.hu\/teaching\/wp-json\/wp\/v2\/media?parent=2593"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}