{"id":6035,"date":"2017-10-09T19:56:25","date_gmt":"2017-10-09T19:56:25","guid":{"rendered":"http:\/\/demos.swarthmore.edu\/physics\/?p=6035"},"modified":"2024-01-19T19:10:39","modified_gmt":"2024-01-19T19:10:39","slug":"measuring-h-with-led","status":"publish","type":"post","link":"https:\/\/demos.swarthmore.edu\/physics\/2017\/10\/measuring-h-with-led\/","title":{"rendered":"Measuring h with LED"},"content":{"rendered":"<p><a href=\"http:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H1.jpg\" rel=\"attachment wp-att-6024\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-6024 aligncenter\" src=\"http:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H1-169x300.jpg\" alt=\"measuring H1\" width=\"331\" height=\"588\" srcset=\"https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H1-169x300.jpg 169w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H1-768x1365.jpg 768w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H1-576x1024.jpg 576w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H1-772x1373.jpg 772w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H1-351x624.jpg 351w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H1.jpg 986w\" sizes=\"(max-width: 331px) 100vw, 331px\" \/><\/a><\/p>\n<p><strong>How to measure Planck&#8217;s constant using an LED<\/strong><\/p>\n<ul>\n<li>Measure LED threshold voltage using voltmeter and ammeter.<\/li>\n<li>LED converts electron energy to photons. Energy lost by electron = energy gained by photon = (electron charge) times (voltage).<\/li>\n<li>So, if threshold voltage is 2.2 volts, energy of emitted photon must be 2.2 eV.<\/li>\n<li>Use\u00a0 E=hc\/lambda, and measure lambda using Red Tide spectrometer with Logger Pro (see below pic), to determine h. Take data using LEDs of 4 different colors and fit data to line with slope h.<\/li>\n<li>Hand held spectrometer can be used to view LED spectrum.<\/li>\n<\/ul>\n<p><a href=\"http:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H.jpg\" rel=\"attachment wp-att-6021\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-6021 aligncenter\" src=\"http:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H-300x169.jpg\" alt=\"measuring H\" width=\"564\" height=\"318\" srcset=\"https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H-300x169.jpg 300w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H-768x432.jpg 768w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H-1024x576.jpg 1024w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H-772x434.jpg 772w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H-624x351.jpg 624w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H.jpg 1753w\" sizes=\"(max-width: 564px) 100vw, 564px\" \/><\/a><br \/>\n<img loading=\"lazy\" decoding=\"async\" class=\"wp-image-6027 aligncenter\" src=\"http:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H4-169x300.jpg\" alt=\"measuring H4\" width=\"253\" height=\"449\" srcset=\"https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H4-169x300.jpg 169w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H4-768x1365.jpg 768w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H4-576x1024.jpg 576w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H4-772x1373.jpg 772w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H4-351x624.jpg 351w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H4.jpg 986w\" sizes=\"(max-width: 253px) 100vw, 253px\" \/><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-6026 aligncenter\" src=\"http:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H3-300x169.jpg\" alt=\"measuring H3\" width=\"483\" height=\"272\" srcset=\"https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H3-300x169.jpg 300w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H3-768x432.jpg 768w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H3-1024x576.jpg 1024w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H3-772x434.jpg 772w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H3-624x351.jpg 624w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H3.jpg 1753w\" sizes=\"(max-width: 483px) 100vw, 483px\" \/><\/p>\n<p style=\"text-align: center;\"><a href=\"http:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2018\/06\/measuring-h.jpg\" rel=\"attachment wp-att-6155\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-6155\" src=\"http:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2018\/06\/measuring-h-300x169.jpg\" alt=\"measuring h\" width=\"745\" height=\"419\" srcset=\"https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2018\/06\/measuring-h-300x169.jpg 300w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2018\/06\/measuring-h-768x432.jpg 768w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2018\/06\/measuring-h-1024x576.jpg 1024w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2018\/06\/measuring-h-772x434.jpg 772w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2018\/06\/measuring-h-624x351.jpg 624w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2018\/06\/measuring-h.jpg 1594w\" sizes=\"(max-width: 745px) 100vw, 745px\" \/><\/a><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-6025 aligncenter\" src=\"http:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H2-300x169.jpg\" alt=\"measuring H2\" width=\"467\" height=\"263\" srcset=\"https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H2-300x169.jpg 300w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H2-768x432.jpg 768w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H2-1024x576.jpg 1024w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H2-772x434.jpg 772w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H2-624x351.jpg 624w, https:\/\/demos.swarthmore.edu\/physics\/wp-content\/uploads\/sites\/2\/2017\/10\/measuring-H2.jpg 1753w\" sizes=\"(max-width: 467px) 100vw, 467px\" \/><\/p>\n","protected":false},"excerpt":{"rendered":"<p>How to measure Planck&#8217;s constant using an LED Measure LED threshold voltage using voltmeter and ammeter. LED converts electron energy to photons. Energy lost by electron = energy gained by photon = (electron charge) times (voltage). So, if threshold voltage is 2.2 volts, energy of emitted photon must be 2.2 eV. Use\u00a0 E=hc\/lambda, and measure &hellip; <a href=\"https:\/\/demos.swarthmore.edu\/physics\/2017\/10\/measuring-h-with-led\/\" class=\"more-link\">Continue reading <span class=\"screen-reader-text\">Measuring h with LED<\/span><\/a><\/p>\n","protected":false},"author":4,"featured_media":6021,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[80,8,50,61,1],"tags":[647,645,644,646],"_links":{"self":[{"href":"https:\/\/demos.swarthmore.edu\/physics\/wp-json\/wp\/v2\/posts\/6035"}],"collection":[{"href":"https:\/\/demos.swarthmore.edu\/physics\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/demos.swarthmore.edu\/physics\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/demos.swarthmore.edu\/physics\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/demos.swarthmore.edu\/physics\/wp-json\/wp\/v2\/comments?post=6035"}],"version-history":[{"count":4,"href":"https:\/\/demos.swarthmore.edu\/physics\/wp-json\/wp\/v2\/posts\/6035\/revisions"}],"predecessor-version":[{"id":6156,"href":"https:\/\/demos.swarthmore.edu\/physics\/wp-json\/wp\/v2\/posts\/6035\/revisions\/6156"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/demos.swarthmore.edu\/physics\/wp-json\/wp\/v2\/media\/6021"}],"wp:attachment":[{"href":"https:\/\/demos.swarthmore.edu\/physics\/wp-json\/wp\/v2\/media?parent=6035"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/demos.swarthmore.edu\/physics\/wp-json\/wp\/v2\/categories?post=6035"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/demos.swarthmore.edu\/physics\/wp-json\/wp\/v2\/tags?post=6035"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}