{"id":83,"date":"2015-07-30T13:32:13","date_gmt":"2015-07-30T17:32:13","guid":{"rendered":"https:\/\/courses.bowdoin.edu\/physics-1140-lab-manual\/lab5\/physics-1140-lab-5-measurement-of-light-spectra-with-a-monochromator\/"},"modified":"2019-03-27T11:55:19","modified_gmt":"2019-03-27T15:55:19","slug":"lab-5-background","status":"publish","type":"page","link":"https:\/\/courses.bowdoin.edu\/physics-1140-lab-manual\/physics-1140-lab-5-measurement-of-light-spectra-with-a-monochromator-4\/lab-5-background\/","title":{"rendered":"Lab 5: Background"},"content":{"rendered":"<p>The human vision system is remarkable in many ways, but it is not particularly good at determining the spectrum of a light source: the intensity of light (the rate at which electromagnetic energy passes through a specified area) as a function of wavelength or frequency. We can learn a lot about the physical properties of light sources by considering their spectra, so instruments like <a href=\"https:\/\/courses.bowdoin.edu\/physics-1140-lab-manual\/lab-4-using-a-spectrometer-to-study-the-reflection-refraction-and-dispersion-of-light-by-a-prism-4\/lab-4-equipment\/#spectometer\">spectrometers<\/a> and <a href=\"https:\/\/courses.bowdoin.edu\/physics-1140-lab-manual\/physics-1140-lab-5-measurement-of-light-spectra-with-a-monochromator-4\/lab-5-equipment\/#Monochromator\">monochromators<\/a> were developed to improve the accuracy and precision of our observations.<\/p>\n<p>The current incarnation of this lab was inspired by a <a href=\"https:\/\/www.bowdoin.edu\/neuroscience\/\">Bowdoin Neuroscience<\/a> <a href=\"http:\/\/cbbcat.net\/record=b3163331~S5\">honors project<\/a>, the goal of which was to study the effect of testosterone on retinal activity in goldfish. How did this come to the attention of the department of <a href=\"http:\/\/www.bowdoin.edu\/physics\/\">Physics and Astronomy<\/a>?<\/p>\n<p><a href=\"http:\/\/dailysun.bowdoin.edu\/2010\/07\/bowdoin-goldfish-research-nets-new-info-on-sexual-behavior\/\"><img loading=\"lazy\" decoding=\"async\" class=\"alignright\" src=\"https:\/\/courses.bowdoin.edu\/physics-1140-lab-manual\/wp-content\/uploads\/sites\/105\/2015\/07\/goldfish.jpg\" alt=\"Two goldfish\" width=\"140\" height=\"80\" \/><\/a><\/p>\n<ul>\n<li>Lighting matters when you&#8217;re studying vision systems. The light source should be characterized for replication purposes. Suppose that the bulb you used originally is now <a href=\"http:\/\/en.wikipedia.org\/wiki\/Phase-out_of_incandescent_light_bulbs\">unavailable<\/a>. How do you know if the replacement is close to equivalent? You need to know the spectrum of each bulb.<\/li>\n<li id=\"SolarSpectrum\">If you&#8217;re studying vision using fish in a lab, you probably want to mimic sunlight. How difficult is that? You&#8217;ll see today that bulb manufacturer&#8217;s claims are not to be trusted.<img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-2449 size-large\" src=\"https:\/\/courses.bowdoin.edu\/physics-1140-lab-manual\/wp-content\/uploads\/sites\/105\/2018\/03\/sunlight_wavelength-1024x618.png\" alt=\"\" width=\"625\" height=\"377\" srcset=\"https:\/\/courses.bowdoin.edu\/physics-1140-lab-manual\/wp-content\/uploads\/sites\/105\/2018\/03\/sunlight_wavelength-1024x618.png 1024w, https:\/\/courses.bowdoin.edu\/physics-1140-lab-manual\/wp-content\/uploads\/sites\/105\/2018\/03\/sunlight_wavelength-150x90.png 150w, https:\/\/courses.bowdoin.edu\/physics-1140-lab-manual\/wp-content\/uploads\/sites\/105\/2018\/03\/sunlight_wavelength-300x181.png 300w, https:\/\/courses.bowdoin.edu\/physics-1140-lab-manual\/wp-content\/uploads\/sites\/105\/2018\/03\/sunlight_wavelength-768x463.png 768w, https:\/\/courses.bowdoin.edu\/physics-1140-lab-manual\/wp-content\/uploads\/sites\/105\/2018\/03\/sunlight_wavelength-624x376.png 624w, https:\/\/courses.bowdoin.edu\/physics-1140-lab-manual\/wp-content\/uploads\/sites\/105\/2018\/03\/sunlight_wavelength.png 1041w\" sizes=\"auto, (max-width: 625px) 100vw, 625px\" \/>(Sunlight spectrum in space as a function of wavelength. Public Domain Image, image source: Christopher S. Baird, data source: American Society for Testing and Materials Terrestrial Reference)<\/li>\n<li>The spectrum of radiation from the Sun is reasonably close to that of thermal radiation corresponding to a temperature of 5800 K.<\/li>\n<li>What&#8217;s the best way to combine multiple light sources into one beam to mimic the solar spectrum? You&#8217;ll figure this out towards the end of the lab.<\/li>\n<\/ul>\n<p><a href=\"https:\/\/courses.bowdoin.edu\/physics-1140-lab-manual\/physics-1140-lab-5-measurement-of-light-spectra-with-a-monochromator-4\/lab-5-equipment\/\"> Equipment<\/a> <a href=\"https:\/\/courses.bowdoin.edu\/physics-1140-lab-manual\/physics-1140-lab-5-measurement-of-light-spectra-with-a-monochromator-4\/lab-5-data-collection-and-analysis\/\">Data Collection and Analysis<\/a> <a href=\"https:\/\/courses.bowdoin.edu\/physics-1140-lab-manual\/physics-1140-lab-5-measurement-of-light-spectra-with-a-monochromator-4\/lab-5-summery-questions\/\">Summary Questions<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>The human vision system is remarkable in many ways, but it is not particularly good at determining the spectrum of a light source: the intensity of light (the rate at which electromagnetic energy passes through a specified area) as a function of wavelength or frequency. We can learn a lot about the physical properties of [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":86,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-83","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/courses.bowdoin.edu\/physics-1140-lab-manual\/wp-json\/wp\/v2\/pages\/83","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.bowdoin.edu\/physics-1140-lab-manual\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/courses.bowdoin.edu\/physics-1140-lab-manual\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/courses.bowdoin.edu\/physics-1140-lab-manual\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/courses.bowdoin.edu\/physics-1140-lab-manual\/wp-json\/wp\/v2\/comments?post=83"}],"version-history":[{"count":0,"href":"https:\/\/courses.bowdoin.edu\/physics-1140-lab-manual\/wp-json\/wp\/v2\/pages\/83\/revisions"}],"up":[{"embeddable":true,"href":"https:\/\/courses.bowdoin.edu\/physics-1140-lab-manual\/wp-json\/wp\/v2\/pages\/86"}],"wp:attachment":[{"href":"https:\/\/courses.bowdoin.edu\/physics-1140-lab-manual\/wp-json\/wp\/v2\/media?parent=83"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}