{"id":11941,"date":"2012-06-29T03:00:02","date_gmt":"2012-06-29T08:00:02","guid":{"rendered":"http:\/\/blogs.scienceforums.net\/swansont\/?p=11941"},"modified":"2012-06-29T03:00:02","modified_gmt":"2012-06-29T08:00:02","slug":"handy-but-not-deep-thoughts","status":"publish","type":"post","link":"http:\/\/blogs.scienceforums.net\/swansont\/archives\/11941","title":{"rendered":"Handy, but Not Deep Thoughts"},"content":{"rendered":"<p>A few weeks ago Doug Natelson had a post about <a href=\"http:\/\/nanoscale.blogspot.com\/2012\/06\/handy-numbers-to-know.html\">handy numbers to know<\/a> \u2026 if you&#8217;re doing some kind of physics involving liquid nitrogen or liquid helium, or anything else in which a condensed-matter\/nanoscale physicists might be involved.  (I assume this is in addition to knowing basic constants)<\/p>\n<p>But I do atomic physics.  A few favorite things that help me out if I&#8217;m away from a calculator or reference book, with some additions from my colleagues.  I probably knew more of these, once upon a time.<\/p>\n<p>\u2014 The speed of light can be written as 30 GHz-cm.  Thus a 30 GHz signal has a wavelength of 1 cm.  1 Ghz means 30 cm.<\/p>\n<p>\u2014 1 nanosecond is 1 foot (light travel in a vacuum)<\/p>\n<p>\u2014 a 1 eV photon is 1240 nm<\/p>\n<p>\u2014 Room temperature is 1\/40 eV (kT)<\/p>\n<p>\u2014 Planck&#8217;s constant is 0.4 amu-micron-meters\/second (useful for deBroglie wavelength calculations)<\/p>\n<p>\u2014 There are about $latexpi$ &nbsp;x 10^7 seconds in a year<\/p>\n<p>&nbsp;<\/p>\n<p>General reference:<\/p>\n<p>\u2013  \\(sqrt{g} = pi \\)   (to about 0.3%)  Handy for Pendulum problems \u2014 just cancel or combine the two values.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>A few weeks ago Doug Natelson had a post about handy numbers to know \u2026 if you&#8217;re doing some kind of physics involving liquid nitrogen or liquid helium, or anything else in which a condensed-matter\/nanoscale physicists might be involved. (I &hellip; <a href=\"http:\/\/blogs.scienceforums.net\/swansont\/archives\/11941\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[39],"tags":[],"class_list":["post-11941","post","type-post","status-publish","format-standard","hentry","category-physics"],"_links":{"self":[{"href":"http:\/\/blogs.scienceforums.net\/swansont\/wp-json\/wp\/v2\/posts\/11941","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/blogs.scienceforums.net\/swansont\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/blogs.scienceforums.net\/swansont\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/blogs.scienceforums.net\/swansont\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/blogs.scienceforums.net\/swansont\/wp-json\/wp\/v2\/comments?post=11941"}],"version-history":[{"count":0,"href":"http:\/\/blogs.scienceforums.net\/swansont\/wp-json\/wp\/v2\/posts\/11941\/revisions"}],"wp:attachment":[{"href":"http:\/\/blogs.scienceforums.net\/swansont\/wp-json\/wp\/v2\/media?parent=11941"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/blogs.scienceforums.net\/swansont\/wp-json\/wp\/v2\/categories?post=11941"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/blogs.scienceforums.net\/swansont\/wp-json\/wp\/v2\/tags?post=11941"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}