{"id":4611,"date":"2010-04-15T10:10:28","date_gmt":"2010-04-15T10:10:28","guid":{"rendered":"http:\/\/scienceblogs.com\/principles\/2010\/04\/15\/optics-quiz-what-do-you-get-wi\/"},"modified":"2010-04-15T10:10:28","modified_gmt":"2010-04-15T10:10:28","slug":"optics-quiz-what-do-you-get-wi","status":"publish","type":"post","link":"http:\/\/chadorzel.com\/principles\/2010\/04\/15\/optics-quiz-what-do-you-get-wi\/","title":{"rendered":"Optics Quiz: What Do You Get With Half a Lens?"},"content":{"rendered":"<p>I was starting to type up the next Laser Smackdown entry, when it occurred to me that this was a good point to talk about a neat little thing from optics. It further occurred to me that this would be a good poll\/quiz topic, to see what people think before I give you the real answer.<\/p>\n<p>So, here&#8217;s the scenario: You have a brightly illuminated object, the canonical example being a vertical arrow (it could also be a shadow cast in a beam of light). You take a lens, and put it in front of the arrow, projecting an image of the arrow on a screen, like so:<\/p>\n<p><img decoding=\"async\" src=\"http:\/\/scienceblogs.com\/principles\/wp-content\/blogs.dir\/467\/files\/2012\/04\/i-876298025040b017b1b70255acf73b27-LensQuiz.jpg\" alt=\"i-876298025040b017b1b70255acf73b27-LensQuiz.jpg\" \/><\/p>\n<p>As you can see from the picture, the image that is formed on the screen is inverted&#8211; the arrow points down, rather than up.<\/p>\n<p>Now, imagine taking a card (the black rectangle below the lens) and positioning it right in front of the lens, so it blocks the lower half of the lens. What happens to the image?<\/p>\n<p><script type=\"text\/javascript\" charset=\"utf-8\" src=\"http:\/\/static.polldaddy.com\/p\/3058712.js\"><\/script><br \/>\n<noscript><br \/>\n\t<a href=\"http:\/\/answers.polldaddy.com\/poll\/3058712\/\">What happens to the image when you block the lower half of the lens?<\/a><span style=\"font-size:9px;\"><a href=\"http:\/\/polldaddy.com\/features-surveys\/\">survey software<\/a><\/span><br \/>\n<\/noscript><\/p>\n<p>This is a classical problem, so you have to pick one and only one answer. You can easily check your answer, if you have access to a flashlight and a magnifying glass, but please don&#8217;t do that until <em>after<\/em> you enter your answer, just so we can see what people arrive at from pure reason.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>I was starting to type up the next Laser Smackdown entry, when it occurred to me that this was a good point to talk about a neat little thing from optics. It further occurred to me that this would be a good poll\/quiz topic, to see what people think before I give you the real&hellip; <a class=\"more-link\" href=\"http:\/\/chadorzel.com\/principles\/2010\/04\/15\/optics-quiz-what-do-you-get-wi\/\">Continue reading <span class=\"screen-reader-text\">Optics Quiz: What Do You Get With Half a Lens?<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"1","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[13,7,137,11],"tags":[],"class_list":["post-4611","post","type-post","status-publish","format-standard","hentry","category-education","category-physics","category-polls","category-science","entry"],"_links":{"self":[{"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/posts\/4611","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/comments?post=4611"}],"version-history":[{"count":0,"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/posts\/4611\/revisions"}],"wp:attachment":[{"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/media?parent=4611"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/categories?post=4611"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/tags?post=4611"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}