{"id":20,"date":"2024-10-24T11:28:09","date_gmt":"2024-10-24T15:28:09","guid":{"rendered":"https:\/\/sites.temple.edu\/chemdemo\/?p=20"},"modified":"2024-10-25T16:22:27","modified_gmt":"2024-10-25T20:22:27","slug":"cathode-ray-tube","status":"publish","type":"post","link":"https:\/\/sites.temple.edu\/chemdemo\/2024\/10\/24\/cathode-ray-tube\/","title":{"rendered":"Cathode Ray Tube"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\">Purpose<\/h2>\n\n\n\n<p>Show how electrons were discovered and that they are charged.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Procedure<\/h2>\n\n\n\n<p>Refer to the instruction manual for the cathode ray tube (CRT).<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Description<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Principle of CRT<\/strong>: Explains the functioning of the cathode ray tube.<\/li>\n\n\n\n<li><strong>Electron Beam View<\/strong>: Provides a clear view of the electron beam from the gun.<\/li>\n\n\n\n<li><strong>Power Requirements<\/strong>:<\/li>\n\n\n\n<li><strong>Heater<\/strong>: 6.3VAC or DC Source needed.<\/li>\n\n\n\n<li><strong>Accelerating Voltage<\/strong>: 150\u2013300V Source required.<\/li>\n\n\n\n<li><strong>Deflecting Plates<\/strong>: \u00b150VDC Source necessary.<\/li>\n\n\n\n<li><strong>Power Supply<\/strong>:<\/li>\n\n\n\n<li>Model: S43951P (sold separately)<\/li>\n\n\n\n<li>Integrates heater, acceleration, and deflection voltages.<\/li>\n\n\n\n<li><strong>Plate Dimensions<\/strong>: Measures 12 x 0.38 x 4.25 in. (30.5 x 0.97 x 10.8 cm).<\/li>\n\n\n\n<li><strong>Weight<\/strong>: 12 oz. (350g).<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Links<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><a href=\"http:\/\/building.pbworks.com\/Thomson-and-the-cathode-ray-tube\">Thomson and the Cathode Ray Tube<\/a><\/li>\n\n\n\n<li><a href=\"http:\/\/building.pbworks.com\/Thomson-and-the-cathode-ray-tube\">Thomson and the Cathode Ray Tube<\/a><\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Experimental Setup<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Equipment<\/strong>: Partially evacuated glass cylinder of various shapes with two metal electrodes (one at each end).<\/li>\n\n\n\n<li><strong>High Voltage Application<\/strong>: When a high voltage is applied between the electrodes, electrons travel in straight lines from the cathode to the anode.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Chemical Concepts Demonstrated<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Cathode rays<\/li>\n\n\n\n<li>Electrons<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Demonstration<\/h2>\n\n\n\n<ol class=\"wp-block-list\">\n<li>Touch one end of a Crookes&#8217; tube with a Tesla coil.<\/li>\n\n\n\n<li>Bring a horseshoe magnet near the tube.<\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Alternative<\/strong>: Connect the tube to a vacuum pump.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Observations<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The tube emits a glow in a straight line until the magnet is introduced, bending the glow into a curved line.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Explanations<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Cathode Rays<\/strong>: Streams of negatively charged particles (electrons).<\/li>\n\n\n\n<li><strong>Behavior of Cathode Rays<\/strong>:<\/li>\n\n\n\n<li>Contained in a glass tube that is partially evacuated.<\/li>\n\n\n\n<li>When connected to batteries, the cathode rays cause the opposite end of the tube to glow.<\/li>\n\n\n\n<li>Deflection by a magnetic field suggests that cathode rays are negatively charged.<\/li>\n\n\n\n<li>A solid object in the path of cathode rays casts a shadow on the wall opposite the cathode.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Historical Context<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Crookes Tube<\/strong>: An early electrical discharge tube invented by William Crookes and others (1869-1875) where cathode rays (electrons) were first discovered.<\/li>\n\n\n\n<li><strong>Usage<\/strong>: Utilized by Crookes, Hittorf, Pl\u00fccker, Goldstein, Hertz, Lenard, and others to study cathode ray properties, culminating in J.J. Thomson&#8217;s 1897 identification of cathode rays as negatively charged particles, later named electrons.<\/li>\n\n\n\n<li><strong>Deflection by Magnetic Fields<\/strong>:<\/li>\n\n\n\n<li>Crookes placed a magnet across the neck of the tube, showing that the beam bends under a magnetic field, akin to electric currents in a generator, confirming that cathode rays obey Faraday&#8217;s law.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Purpose Show how electrons were discovered and that they are charged. Procedure Refer to the instruction manual for the cathode ray tube (CRT). Description Links&#8230;<\/p>\n<div class=\"more-link-wrapper\"><a class=\"more-link\" href=\"https:\/\/sites.temple.edu\/chemdemo\/2024\/10\/24\/cathode-ray-tube\/\">Continue Reading<span class=\"screen-reader-text\">Cathode Ray Tube<\/span><\/a><\/div>\n","protected":false},"author":36673,"featured_media":0,"comment_status":"open","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[],"class_list":["post-20","post","type-post","status-publish","format-standard","hentry","category-demonstrations","entry"],"_links":{"self":[{"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/posts\/20","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/users\/36673"}],"replies":[{"embeddable":true,"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/comments?post=20"}],"version-history":[{"count":1,"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/posts\/20\/revisions"}],"predecessor-version":[{"id":23,"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/posts\/20\/revisions\/23"}],"wp:attachment":[{"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/media?parent=20"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/categories?post=20"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/tags?post=20"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}