File "multiple-slit-interference.html"
Path: /StudyIB/physics/page/1126/multiple-slit-interferencehtml
File size: 63.41 KB
MIME-type: text/html
Charset: utf-8
<!DOCTYPE html><html lang="EN"><head> <script>(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start': new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0], j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src= 'https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f); })(window,document,'script','dataLayer','GTM-PZBWZ8J');</script> <title>Multiple slit interference</title><!-- Removed by WebCopy --><!--<base href="/">--><!-- Removed by WebCopy --><meta http-equiv="x-ua-compatible" content="IE=Edge"><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1"><link href="../../../css/bootstrap.flatly.min.css" rel="stylesheet" media="screen"><link rel="stylesheet" href="../../../fonts/awesome/css/font-awesome.min.css"><link href="../../../js/jquery-fancybox/jquery.fancybox.min.css" type="text/css" rel="stylesheet"><link rel="stylesheet" href="../../../css/style.min.css?v=202301301645"><meta name="robots" content="index, follow"><meta name="googlebot" content="noarchive"><meta prefix="og: http://ogp.me/ns#" property="og:title" name="og:title" content="StudyIB Physics: Multiple slit interference"> <meta prefix="og: http://ogp.me/ns#" property="og:image" content="https://studyib.net/img/studyib-card-default.jpg"> <meta prefix="og: http://ogp.me/ns#" property="og:description" name="og:description" content="When light passes through two or more slits, it interferes. A pattern can be observed if the waves are coherent. The effect continues with multiple slits or a diffraction grating."> <meta prefix="og: http://ogp.me/ns#" property="og:url" name="og:url" content="https://studyib.net/physics/page/1126/multiple-slit-interference"> <meta prefix="og: http://ogp.me/ns#" property="og:site_name" name="og:site_name" content="StudyIB - Your IB learning companion"> <meta prefix="og: http://ogp.me/ns#" property="og:locale" name="og:locale" content="en"> <meta prefix="og: http://ogp.me/ns#" property="og:type" name="og:type" content="website"> <meta name="description" content="When light passes through two or more slits, it interferes. A pattern can be observed if the waves are coherent. The effect continues with multiple slits or a diffraction grating."> <meta name="image" content="https://studyib.net/img/studyib-card-default.jpg"> <meta name="keywords" content="StudyIB, Physics, Site overview, Self-study, Videos, Virtual tutor, Practices, Multiple Choice, IB, IBDP, InThinking, International Baccalaureate, Revision, Revision websites, Student Sites, Students, Learning, Guidance, Exam, Questions"> <meta itemprop="name" content="StudyIB Physics: Multiple slit interference"> <meta itemprop="description" content="When light passes through two or more slits, it interferes. A pattern can be observed if the waves are coherent. The effect continues with multiple slits or a diffraction grating."> <meta itemprop="image" content="https://studyib.net/img/studyib-card-default.jpg"> <meta name="twitter:card" content="summary_large_image"> <meta name="twitter:title" content="StudyIB Physics: Multiple slit interference"> <meta name="twitter:description" content="When light passes through two or more slits, it interferes. A pattern can be observed if the waves are coherent. The effect continues with multiple slits or a diffraction grating."> <meta name="twitter:image" content="https://studyib.net/img/studyib-card-default.jpg"> <meta name="twitter:creator" content="@inthinker"><link rel="stylesheet" href="../../../css/snippets.min.css?v=202209111300"><link rel="stylesheet" href="../../../css/article.min.css?v=202211221000"><link rel="stylesheet" type="text/css" href="../../../js/slick-carousel/slick.min.css"><link rel="stylesheet" type="text/css" href="../../../js/slick-carousel/slick-theme.min.css"><style type="text/css">.filter-sl-only { display: none; }</style><script src="../../../ajax/libs/mathjax/2.7.0/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script><script src="../../../js/ifvisible.min.js"></script><script>ifvisible.setIdleDuration(300);</script><link rel="apple-touch-icon-precomposed" sizes="57x57" href="../../../img/favicon/apple-touch-icon-57x57.png"> <link rel="apple-touch-icon-precomposed" sizes="114x114" href="../../../img/favicon/apple-touch-icon-114x114.png"> <link rel="apple-touch-icon-precomposed" sizes="72x72" href="../../../img/favicon/apple-touch-icon-72x72.png"> <link rel="apple-touch-icon-precomposed" sizes="144x144" href="../../../img/favicon/apple-touch-icon-144x144.png"> <link rel="apple-touch-icon-precomposed" sizes="60x60" href="../../../img/favicon/apple-touch-icon-60x60.png"> <link rel="apple-touch-icon-precomposed" sizes="120x120" href="../../../img/favicon/apple-touch-icon-120x120.png"> <link rel="apple-touch-icon-precomposed" sizes="76x76" href="../../../img/favicon/apple-touch-icon-76x76.png"> <link rel="apple-touch-icon-precomposed" sizes="152x152" href="../../../img/favicon/apple-touch-icon-152x152.png"> <link rel="icon" type="image/png" href="../../../img/favicon/favicon-196x196.png" sizes="196x196"> <link rel="icon" type="image/png" href="../../../img/favicon/favicon-96x96.png" sizes="96x96"> <link rel="icon" type="image/png" href="../../../img/favicon/favicon-32x32.png" sizes="32x32"> <link rel="icon" type="image/png" href="../../../img/favicon/favicon-16x16.png" sizes="16x16"> <link rel="icon" type="image/png" href="../../../img/favicon/favicon-128.png" sizes="128x128"> <meta name="application-name" content="StudyIB: Your IB Learning Companion"> <meta name="msapplication-TileColor" content="#A5BED5"> <meta name="msapplication-TileImage" content="/img/favicon/mstile-144x144.png"> <meta name="msapplication-square70x70logo" content="/img/favicon/mstile-70x70.png"> <meta name="msapplication-square150x150logo" content="/img/favicon/mstile-150x150.png"> <meta name="msapplication-wide310x150logo" content="/img/favicon/mstile-310x150.png"> <meta name="msapplication-square310x310logo" content="/img/favicon/mstile-310x310.png"><script>var stdHash = "6da675cbcb3d25f050b05557349abc79", stdTicket = "082b9c9c4ae3624d";</script><script src="../../../js/user/local-stats.min.js?v=202205311700"></script><link href="../../../css/subjects-frontpage.min.css?v=202302031000" rel="stylesheet"></head><body class="public physics"> <noscript><iframe src="https://www.googletagmanager.com/ns.html?id=GTM-PZBWZ8J" height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript> <div id="top-header"> <div class="wmap general hidden-sm hidden-xs subjects"> <div class="layout-wrapper"> <div class="container-fluid"> <a href=""> <img class="header-thinker" src="../../../img/header-thinker.svg"> </a> <h1> <a href="../../../physics.html"> IBDP Physics </a> <a href="https://inthinking.net" title="inthinking.net" class="inthinking-logo pull-right"> <img src="../../../img/header-logo.svg" style="height: 80px; width: auto;"> </a> </h1> <p class="slogan">InThinking Revision Sites for students</p> <p class="author">Website by <strong>Chris Hamper & Emma Mitchell</strong></p> <p class="updated">Updated 3 February 2023</p> </div> </div> </div> <nav id="public-topnav" class="navbar navbar-default"> <div class="container-fluid"> <div class="navbar-header"> <a class="navbar-brand hidden-md hidden-lg" href="../../../index.htm"> <img class="header-xs-thinker" src="../../../img/header-thinker.svg"> </a> <button type="button" class="collapsed navbar-toggle" data-toggle="collapse" data-target="#subject-navbar-collapse" aria-expanded="false"> <span class="sr-only">Toggle navigation</span> <i class="fa fa-fw fa-2x fa-user"></i> </button> <div class="brand hidden-lg hidden-md hidden-sm"> <a class="brand-xs" href="../../../physics.html"> <strong class="title" style="white-space: nowrap;font-size: 18px;">Physics</strong> </a> </div> </div> <div class="collapse navbar-collapse" id="subject-navbar-collapse"> <ul class="nav navbar-bar navbar-userbox hidden-md hidden-lg"><li class="dropdown"><a href="#" class="dropdown-toggle" data-toggle="dropdown"><i class="fa fa-fw fa-lg fa-user-circle" style="margin-right: 5px;"></i><span style="font-size: 16px;"></span></a><ul class="dropdown-menu"><li class="dropdown-submenu"><a class="dropdown-toggle" href="#" data-toggle="dropdown"><i class="fa fa-fw fa-globe"></i> Subjects</a><ul class="dropdown-menu"><li></li><li class=""><a href="../../../biology.html">DP Biology</a></li><li class=""><a href="../../../chemistry.html">DP Chemistry</a></li><li class=""><a href="../../../englishalanglit.html">DP English A: Language & Literature</a></li><li class=""><a href="../../../mathsanalysis.html">DP Maths: Analysis & Approaches</a></li><li class=""><a href="../../../mathsapplications.html">DP Maths: Applications & Interpretations SL</a></li><li class="active"><a href="../../../physics.html"><i class="fa fa-caret-right"></i> DP Physics</a></li><li class=""><a href="../../../spanishb.html">DP Spanish B</a></li></ul></li><li class="menu-item"><a href="../../../user.html"><i class="fa fa-fw fa-dashboard"></i> Dashboard</a></li><li class="menu-item"><a href="../../../user/profile.html"><i class="fa fa-fw fa-cog"></i> My profile</a></li><li class="menu-item"><a href="../../../user/messages.html"><i class="fa fa-fw fa-envelope"></i> Messages</a></li><li class="menu-item hidden-md hidden-lg mt-xs-3"><a href="../../../index.htm?logout=1" class="btn btn-primary btn-xs-block"><i class="fa fa-fw fa-lg fa-power-off text-danger"></i>Log out</a></li></ul></li></ul> <ul class="nav navbar-bar"><li class=""><a class="home" href="../../../physics.html"><i class="fa fa-fw fa-home"></i> Home</a></li><li class=""><a class="topics" href="#"><i class="fa fa-fw fa-th-large"></i> Topics</a></li><li class=""><a class="favorites" href="../../../physics.html"><i class="fa fa-fw fa-star"></i> My favorites</a></li><li class=""><a class="" href="../../flashcards.html"><i class="fa fa-fw fa-bolt"></i> Flashcards</a></li><li class=""><a class="qbank" href="../../test-your-knowledge.html"><i class="fa fa-fw fa-question"></i> Question bank</a></li><li class=""><a class="networks" href="../../networks.html"><i class="fa fa-fw fa-graduation-cap"></i> Virtual tutor</a></li><li class=""><a class="" href="../../blogs.html"><i class="fa fa-fw fa-paperclip"></i> Blog</a></li><li class=""><a class="sitemap" href="../../sitemap.html"><i class="fa fa-fw fa-sitemap"></i> Sitemap</a></li><li class=""><a class="activity" href="../../../physics.html"><i class="fa fa-fw fa-calendar-check-o"></i> My activity</a></li></ul> <ul class="nav navbar-bar navbar-right"> <li> <form class="navbar-form hidden-md hidden-lg" role="search" method="get" action="physics/search"> <div class="input-group"> <input class="form-control nav-search" name="glob" type="search" placeholder="Search..."> <span class="input-group-btn"> <button type="submit" class="btn bg-blue"> <i class="fa fa-search"> </i> </button> </span> </div> </form> <a href="#" class="toggle-menu-search hidden-sm hidden-xs" data-toggle="dropdown"> <i class="fa fa-lg fa-search"></i> </a> </li></ul> </div> </div></nav><nav id="nav-menu-search" class="shadow-bottom hidden-sm hidden-xs" style="display: none;"> <div class="container-fluid"> <form class="" role="search" method="get" action="physics/search"> <input class="form-control nav-search" name="glob" type="search" placeholder="Search Physics..."> <button class="btn btn-sm btn-primary" type="submit"> Search </button> </form> </div></nav><div class="modal fade" tabindex="-1" role="dialog" id="modal-mini-login"> <div class="modal-dialog" role="document"> <div class="modal-content"> <div class="modal-body"> <button aria-hidden="true" data-dismiss="modal" class="close hidden-xs login-button-close" type="button">×</button> <form method="post"> <div class="form-group"> <input name="user-email" class="form-control" type="text" placeholder="Email"> </div> <div class="form-group"> <input name="user-password" class="form-control" type="password" placeholder="Password"> <input name="user-fp" class="fp" value="d8c893da5db7501669ffeeac46273ba6" type="hidden"> </div> <div class="form-group"> <a href="../../../reset-password.html" class="reset-password" style="font-weight: normal;"> Forgot your password? </a> </div> <div class="form-group"> <button type="submit" name="submit-login" value="1" class="btn btn-primary btn-block text-center"> <i class="fa fa-user fa-fw"></i> Log in </button> </div> </form> </div> </div> </div></div></div><div class="modal fade" id="show-topics" tabindex="-1" role="dialog"><div id="dialog-topics" class="modal-dialog modal-dialog-topics"><div class="modal-content"><div class="modal-body modal-body-topics"><div id="new-frontpage-toplevels-topics" class="frontpage-box"><div class="row"><div class="col-md-4 col-sm-4"><div class="item"><a href="../3015/free-access-weekend.html"><div class="header" style="height: 35px;"><h3 class="title special" style="margin-top: 0;">Free Access Weekend!</h3></div><div class="body"><div class="cropper" style="background-image: url('../../free.jpg'); height: 10vw;"></div></div></a></div></div><div class="col-md-4 col-sm-4"><div class="item"><a href="../814/start-here.html"><div class="header" style="height: 35px;"><h3 class="title special" style="margin-top: 0;">Start here</h3></div><div class="body"><div class="cropper" style="background-image: url('/media/physics/getting-started/getting-started.jpg'); height: 10vw;"></div></div></a></div></div><div class="col-md-4 col-sm-4"><div class="item"><a href="../819/revision-tips.html"><div class="header" style="height: 35px;"><h3 class="title special" style="margin-top: 0;">Revision tips</h3></div><div class="body"><div class="cropper" style="background-image: url('/media/physics/getting-started/exam-tips.jpg'); height: 10vw;"></div></div></a></div></div><div class="col-md-4 col-sm-4"><div class="item"><a href="../2885/exam-questions.html"><div class="header" style="height: 35px;"><h3 class="title special" style="margin-top: 0;">Exam questions</h3></div><div class="body"><div class="cropper" style="background-image: url('../../practice-papers/flash-front.png'); height: 10vw;"></div></div></a></div></div><div class="col-md-4 col-sm-4"><div class="item"><a href="../204/basics.html"><div class="header" style="height: 35px;"><h3 class="title special" style="margin-top: 0;">Basics</h3></div><div class="body"><div class="cropper" style="background-image: url('/media/physics/basics/basics.jpg'); height: 10vw;"></div></div></a></div></div><div class="col-md-4 col-sm-4"><div class="item"><a href="../217/mechanics.html"><div class="header" style="height: 35px;"><h3 class="title special" style="margin-top: 0;">Mechanics</h3></div><div class="body"><div class="cropper" style="background-image: url('/media/physics/mechanics/mechanics.jpg'); height: 10vw;"></div></div></a></div></div><div class="col-md-4 col-sm-4"><div class="item"><a href="../252/thermal.html"><div class="header" style="height: 35px;"><h3 class="title special" style="margin-top: 0;">Thermal</h3></div><div class="body"><div class="cropper" style="background-image: url('/media/physics/thermal/thermal.jpg'); height: 10vw;"></div></div></a></div></div><div class="col-md-4 col-sm-4"><div class="item"><a href="../444/oscillations-and-waves.html"><div class="header" style="height: 35px;"><h3 class="title special" style="margin-top: 0;">Oscillations & waves</h3></div><div class="body"><div class="cropper" style="background-image: url('/media/physics/waves/waves.jpg'); height: 10vw;"></div></div></a></div></div><div class="col-md-4 col-sm-4"><div class="item"><a href="../445/electricity-and-magnetism.html"><div class="header" style="height: 35px;"><h3 class="title special" style="margin-top: 0;">Electricity & magnetism</h3></div><div class="body"><div class="cropper" style="background-image: url('/media/physics/electricity/electricity.jpg'); height: 10vw;"></div></div></a></div></div><div class="col-md-4 col-sm-4"><div class="item"><a href="../443/circular-motion-and-gravity.html"><div class="header" style="height: 35px;"><h3 class="title special" style="margin-top: 0;">Circular motion & gravity</h3></div><div class="body"><div class="cropper" style="background-image: url('/media/physics/circular-motion/circular.jpg'); height: 10vw;"></div></div></a></div></div><div class="col-md-4 col-sm-4"><div class="item"><a href="../354/atomic-nuclear-and-particles.html"><div class="header" style="height: 35px;"><h3 class="title special" style="margin-top: 0;">Atomic, nuclear & particles</h3></div><div class="body"><div class="cropper" style="background-image: url('/media/physics/atomic/atomic.jpg'); height: 10vw;"></div></div></a></div></div><div class="col-md-4 col-sm-4"><div class="item"><a href="../446/energy-production.html"><div class="header" style="height: 35px;"><h3 class="title special" style="margin-top: 0;">Energy production</h3></div><div class="body"><div class="cropper" style="background-image: url('/media/physics/energy-production/energy.jpg'); height: 10vw;"></div></div></a></div></div><div class="col-md-4 col-sm-4"><div class="item"><a href="../848/options.html"><div class="header" style="height: 35px;"><h3 class="title special" style="margin-top: 0;">Options</h3></div><div class="body"><div class="cropper" style="background-image: url('/media/physics/astro/options.jpg'); height: 10vw;"></div></div></a></div></div><div class="col-md-4 col-sm-4"><div class="item"><a href="../823/astrophysics.html"><div class="header" style="height: 35px;"><h3 class="title special" style="margin-top: 0;">Astrophysics</h3></div><div class="body"><div class="cropper" style="background-image: url('/media/physics/astro/black-hole.jpg'); height: 10vw;"></div></div></a></div></div><div class="col-md-4 col-sm-4"><div class="item"><a href="../849/engineering.html"><div class="header" style="height: 35px;"><h3 class="title special" style="margin-top: 0;">Engineering</h3></div><div class="body"><div class="cropper" style="background-image: url('/media/physics/engineering/lift-off.jpg'); height: 10vw;"></div></div></a></div></div></div></div></div></div></div></div><div class="container-fluid shadow-ith"><div class="row frontpage"> <div class="col-md-3" id="left-column"> <p class="visible-xs-block"></p><div class="dropdown user-menu hidden-xs" style="margin-bottom: 20px;"> <button type="button" class="btn btn-default dropdown-toggle" data-toggle="dropdown" style="border-radius: 0; padding: 6px 18px;"> <i class="fa fa-fw fa-user-circle"></i> <small><i class="fa fa-caret-down"></i></small> </button> <ul class="dropdown-menu"> <li class="dropdown-submenu"><a href="#"><i class="fa fa-fw fa-globe"></i> Subjects</a><ul id="user-subjects-menu" class="dropdown-menu"><li></li><li class=""><a href="../../../biology.html">DP Biology</a></li><li class=""><a href="../../../chemistry.html">DP Chemistry</a></li><li class=""><a href="../../../englishalanglit.html">DP English A: Language & Literature</a></li><li class=""><a href="../../../mathsanalysis.html">DP Maths: Analysis & Approaches</a></li><li class=""><a href="../../../mathsapplications.html">DP Maths: Applications & Interpretations SL</a></li><li class="active"><a href="../../../physics.html"><i class="fa fa-caret-right"></i> DP Physics</a></li><li class=""><a href="../../../spanishb.html">DP Spanish B</a></li></ul></li><li class="divider"></li><li><a href="../../../user.html"><i class="fa fa-fw fa-dashboard"></i> Dashboard</a></li><li><a href="../../../user/profile.html"><i class="fa fa-fw fa-cog"></i> My profile</a></li><li><a href="../../../user/messages.html"><i class="fa fa-fw fa-envelope"></i> Messages</a></li> <li class="divider"></li> <li> <a href="../../../index.htm?logout=1"> <i class="fa fa-fw fa-power-off"></i> Log out </a> </li> </ul></div> <div id="side-nav"><h4 class="side-nav-title dropdown"><a href="../444/oscillations-and-waves.html" class="dropdown-toggle toplevel-dropdown" data-toggle="dropdown"><i class="fa fa-ellipsis-v"></i></a> <a href="../444/oscillations-and-waves.html">Oscillations and waves</a><ul class="dropdown-menu"><li><a href="../../../physics.html" style="padding-left: 5px; border-bottom: solid 1px #ddd"><i class="fa fa-fw fa-home"></i> Home</a></li><li><a href="../3015/free-access-weekend.html"><i class="fa fa-fw fa-caret-right"></i> Free Access Weekend!</a></li><li><a href="../814/start-here.html"><i class="fa fa-fw fa-caret-right"></i> Start here</a></li><li><a href="../819/revision-tips.html"><i class="fa fa-fw fa-caret-right"></i> Revision tips</a></li><li><a href="../2885/exam-questions.html"><i class="fa fa-fw fa-caret-right"></i> Exam questions</a></li><li><a href="../204/basics.html"><i class="fa fa-fw fa-caret-right"></i> Basics</a></li><li><a href="../217/mechanics.html"><i class="fa fa-fw fa-caret-right"></i> Mechanics</a></li><li><a href="../252/thermal.html"><i class="fa fa-fw fa-caret-right"></i> Thermal</a></li><li><a href="../445/electricity-and-magnetism.html"><i class="fa fa-fw fa-caret-right"></i> Electricity and magnetism</a></li><li><a href="../443/circular-motion-and-gravity.html"><i class="fa fa-fw fa-caret-right"></i> Circular motion and gravity</a></li><li><a href="../354/atomic-nuclear-and-particles.html"><i class="fa fa-fw fa-caret-right"></i> Atomic, nuclear and particles</a></li><li><a href="../446/energy-production.html"><i class="fa fa-fw fa-caret-right"></i> Energy production</a></li><li><a href="../848/options.html"><i class="fa fa-fw fa-caret-right"></i> Options</a></li><li><a href="../823/astrophysics.html"><i class="fa fa-fw fa-caret-right"></i> Astrophysics</a></li><li><a href="../849/engineering.html"><i class="fa fa-fw fa-caret-right"></i> Engineering</a></li></ul><div class="pull-right"><a class="sidenav-expand" title="Expand all" href="#"><i class="fa fa-plus-circle"></i></a> <a class="sidenav-compress" title="Compress all" href="#"><i class="fa fa-minus-circle"></i></a></div></h4><ul class="side-nav level-0"><li class=""><label style="padding-left: 0px"><a class="expander" href="#" style="font-size: .9em"><i class="fa fa-fw fa-caret-right"></i></a><a href="../272/oscillations.html">Oscillations</a></label><ul class="side-nav level-1"><li class=""><label style="padding-left: 14px"><i class="fa fa-fw"></i><a href="../273/simple-pendulum.html">Simple pendulum</a></label></li><li class=""><label style="padding-left: 14px"><i class="fa fa-fw"></i><a href="../276/mass-on-a-spring.html">Mass on a spring</a></label></li><li class=""><label style="padding-left: 14px"><i class="fa fa-fw"></i><a href="../274/equations-for-shm.html">Equations for SHM</a></label></li><li class=""><label style="padding-left: 14px"><i class="fa fa-fw"></i><a href="../275/shm-and-energy.html">SHM and energy</a></label></li><li class=""><label style="padding-left: 14px"><i class="fa fa-fw"></i><a href="../277/phase.html">Phase</a></label></li></ul></li><li class=""><label style="padding-left: 0px"><a class="expander" href="#" style="font-size: .9em"><i class="fa fa-fw fa-caret-right"></i></a><a href="../278/waves.html">Waves</a></label><ul class="side-nav level-1"><li class=""><label style="padding-left: 14px"><i class="fa fa-fw"></i><a href="../279/introduction-to-waves.html">Introduction to waves</a></label></li><li class=""><label style="padding-left: 14px"><i class="fa fa-fw"></i><a href="../365/wave-phenomena.html">Wave phenomena</a></label></li><li class=""><label style="padding-left: 14px"><i class="fa fa-fw"></i><a href="../280/graphical-representation-of-waves.html">Graphical representation of waves</a></label></li><li class=""><label style="padding-left: 14px"><i class="fa fa-fw"></i><a href="../281/standing-waves-on-a-string.html">Standing waves on a string</a></label></li><li class=""><label style="padding-left: 14px"><i class="fa fa-fw"></i><a href="../283/sound.html">Sound</a></label></li><li class=""><label style="padding-left: 14px"><i class="fa fa-fw"></i><a href="../284/light.html">Light</a></label></li></ul></li><li class="expanded parent"><label style="padding-left: 0px"><a class="expander" href="#" style="font-size: .9em"><i class="fa fa-fw fa-caret-right"></i></a><a href="../1128/ahl-waves.html">AHL Waves</a></label><ul class="side-nav level-1"><li class=""><label style="padding-left: 14px"><i class="fa fa-fw"></i><a href="../1122/doppler-effect.html">Doppler effect</a></label></li><li class=""><label style="padding-left: 14px"><i class="fa fa-fw"></i><a href="../1117/simple-harmonic-motion.html">Simple harmonic motion</a></label></li><li class=""><label style="padding-left: 14px"><i class="fa fa-fw"></i><a href="../1127/single-slit-diffraction.html">Single slit diffraction</a></label></li><li class=""><label style="padding-left: 14px"><i class="fa fa-fw"></i><a href="../1123/resolution.html">Resolution</a></label></li><li class="expanded parent selected"><label style="padding-left: 14px"><i class="fa fa-fw"></i><a href="multiple-slit-interference.html">Multiple slit interference</a></label></li><li class=""><label style="padding-left: 14px"><i class="fa fa-fw"></i><a href="../1124/thin-film-interference.html">Thin film interference</a></label></li></ul></li></ul></div> <div class="hidden-xs hidden-sm"> <button class="btn btn-default btn-block text-xs-center" data-toggle="modal" data-target="#modal-feedback" style="margin-bottom: 10px"><i class="fa fa-send"></i> Feedback</button> </div> </div> <div class="col-md-9" id="main-column"> <h1 class="page_title"> Multiple slit interference <a href="#" class="mark-page-favorite pull-right" data-pid="1126" title="Mark as favorite" onclick="return false;"><i class="fa fa-star-o"></i></a> </h1> <ol class="breadcrumb"> <li><a href="../../../physics.html"><i class="fa fa-home"></i></a><i class="fa fa-fw fa-chevron-right divider"></i></li><li><a href="../444/oscillations-and-waves.html">Oscillations and waves</a><i class="fa fa-fw fa-chevron-right divider"></i></li><li><a href="../1128/ahl-waves.html">AHL Waves</a><i class="fa fa-fw fa-chevron-right divider"></i></li><li><span class="gray">Multiple slit interference</span></li> <span class="pull-right" style="color: #555" title="Suggested study time: 30 minutes"><i class="fa fa-clock-o"></i> 30'</span> </ol> <article id="main-article"> <p><img alt="" src="../../waves/interference.jpg" style="float: left; width: 250px; height: 161px;">We now understand the diffraction effect of a single slit on light passing through. But what about two slits?</p> <p>When light passes through two or more slits, it interferes. A pattern can be observed if the waves are coherent. The effect continues with multiple slits or a diffraction grating.</p> <hr class="hidden-separator"> <div class="panel panel-turquoise panel-has-colored-body"> <div class="panel-heading"> <div> <p>Key Concepts</p> </div> </div> <div class="panel-body"> <div>The phenonoma discussed on this page rely on coherent light. Coherent light beams have constant phase difference (and therefore the same frequency). They should also have the same amplitude.</div> <div> <div class="panel panel-turquoise panel-has-colored-body panel-has-border panel-expandable"> <div class="panel-heading"><a class="expander" href="#"><span class="fa fa-plus"></span></a> <div> <p>Young's double slit experiment</p> </div> </div> <div class="panel-body"> <div> <p>The Young's double slit experiment consisted of a beam of coherent light passing through two identical slits before striking a screen.</p> <p style="text-align: center;"><img alt="" src="../../waves/double.png" style="width: 250px; height: 133px;"></p> <p>The result is a pattern of evenly spaced bright fringes separated by dark fringes. It is caused by the interference of the light from the two slits as the two paths to each point on the screen vary in distance. The central maximum is most intense.</p> <p style="text-align: center;"><img alt="" src="../../waves/double-6.png" style="width: 97px; height: 214px;"></p> <p>The fringe spacing can be calculated as follows:</p> <p style="text-align: center;"><span class="math-tex">\(s={D\lambda\over d}\)</span></p> <ul> <li><span class="math-tex">\(s\)</span> is the distance between consecutive maxima (m)</li> <li><span class="math-tex">\(D\)</span> is the distance from the slits to the screen (m)</li> <li><span class="math-tex">\(\lambda\)</span> is the wavelength of light (m)</li> <li><span class="math-tex">\(d\)</span> is the distance separating the centres of the two slits (m)</li> </ul> <p style="text-align: center;"><img alt="" src="../../waves/double-3.png" style="width: 250px; height: 151px;"></p> <p>The fringe spacing is increaed by increasing the distance between the slits and the screen or by reducing the slit separation. It is also increased by increasing the wavelength of the light.</p> <div class="video-embed vimeo"><iframe allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen="" mozallowfullscreen="" webkitallowfullscreen="" height="420" width="100%" src="https://player.vimeo.com/video/369635833"></iframe></div> <p style="text-align: center;"><iframe height="471px" scrolling="no" src="https://tube.geogebra.org/material/iframe/id/1276791/width/642/height/471/border/888888/rc/false/ai/false/sdz/false/smb/false/stb/false/stbh/true/ld/false/sri/true/at/auto" style="border:0px;" width="642px"></iframe></p> <div class="video-embed vimeo"><iframe allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen="" mozallowfullscreen="" webkitallowfullscreen="" height="420" width="100%" src="https://player.vimeo.com/video/369635967"></iframe></div> </div> </div> <div class="panel-footer"> <div> <p> </p> </div> </div> </div> <div class="panel panel-turquoise panel-has-colored-body panel-has-border panel-expandable"> <div class="panel-heading"><a class="expander" href="#"><span class="fa fa-plus"></span></a> <div> <p>Modulation</p> </div> </div> <div class="panel-body"> <div> <p>When we look beyond the interference pattern shown above, we notice that the intensity of the maxima appears not to follow a straightforward pattern of reducing outward from the centre.</p> <p style="text-align: center;"><img alt="" src="../../waves/double-5.png" style="width: 378px; height: 216px;"></p> <p>The two-slit <strong>interference</strong> pattern is modulated by the one-slit <strong>diffraction</strong> effect.</p> <p>This affects the distribution of intensity against distance on the screen from the centre by capping the double slit pattern within the intensity of the diffraction pattern.</p> <div class="video-embed vimeo"><iframe allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen="" mozallowfullscreen="" webkitallowfullscreen="" height="420" width="100%" src="https://player.vimeo.com/video/369635859"></iframe></div> </div> </div> <div class="panel-footer"> <div> <p> </p> </div> </div> </div> </div> </div> <div class="panel-footer"> <div> </div> </div> </div> <div class="panel panel-has-colored-body panel-yellow"> <div class="panel-heading"><a class="expander" href="#"><span class="fa fa-plus"></span></a> <div> <p>Essentials</p> </div> </div> <div class="panel-body"> <div> <div class="panel panel-has-colored-body panel-has-border panel-yellow"> <div class="panel-heading"><a class="expander" href="#"><span class="fa fa-plus"></span></a> <div> <p>Multiple slits</p> </div> </div> <div class="panel-body"> <div> <p>When light shines through multiple slits, an interference pattern forms similar to that through a double slit.</p> <p style="text-align: center;"><span class="math-tex">\(n\lambda = d \sin \theta\)</span></p> <ul> <li><span class="math-tex">\(n\)</span> is the number (order) of the maximum, where the central maximum is order 0</li> <li><span class="math-tex">\(\lambda\)</span> is the wavelength of the light (m)</li> <li><span class="math-tex">\(d\)</span> is the distance separating the slits (m)</li> <li><span class="math-tex">\(\theta\)</span> is the angle subtended by the maximum and the centre</li> </ul> <p style="text-align: center;"><img alt="" src="../../waves/multiple1.png" style="width: 210px; height: 196px;"><img alt="" src="../../waves/multiple2.png" style="width: 262px; height: 210px;"></p> <p>Subsidiary maxima form in between the overall interference maxima.The number of subsidiary maxima produced is equal to the number of slits minus 2.</p> <div class="video-embed vimeo"><iframe allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen="" mozallowfullscreen="" webkitallowfullscreen="" height="420" width="100%" src="https://player.vimeo.com/video/369636338"></iframe></div> <p>The ratio of <span class="math-tex">\(\text{slit width}\over \text{separation}\)</span> can be obtained using a combination of the single slit diffraction equation and the multiple slit interference equation. At the first diffraction minimum:</p> <p style="text-align: center;"><span class="math-tex">\(\theta = {\lambda\over b}={n\lambda\over d}\Rightarrow {b\over d}={1\over n}\)</span></p> <div class="video-embed vimeo"><iframe allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen="" mozallowfullscreen="" webkitallowfullscreen="" height="420" width="100%" src="https://player.vimeo.com/video/369635920"></iframe></div> <div class="video-embed vimeo"><iframe allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen="" mozallowfullscreen="" webkitallowfullscreen="" height="420" width="100%" src="https://player.vimeo.com/video/369636849"></iframe></div> </div> </div> <div class="panel-footer"> <div> <p> </p> </div> </div> </div> <div class="panel panel-has-colored-body panel-has-border panel-yellow panel-expandable"> <div class="panel-heading"><a class="expander" href="#"><span class="fa fa-plus"></span></a> <div> <p>Diffraction gratings</p> </div> </div> <div class="panel-body"> <div> <p>The more slits added, the more narrow and intense the peaks become.</p> <p>A diffraction grating is an array of identical, equally-spaced slits. The equation used to determine the angles at which maxima are produced is the same as that for multiple slits.</p> <p>You may have to perform an initial calculation to determine <span class="math-tex">\(d\)</span>, the separation of the slits. If you are informed that the grating contains e.g. 100 slits per mm, you would convert this into 100 000 slits per m. The inverse gives the distance between slits in metres.</p> <div class="video-embed vimeo"><iframe allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen="" mozallowfullscreen="" webkitallowfullscreen="" height="420" width="100%" src="https://player.vimeo.com/video/369635782"></iframe></div> </div> </div> <div class="panel-footer"> <div> <p> </p> </div> </div> </div> </div> </div> <div class="panel-footer"> <div> </div> </div> </div> <div class="panel panel-has-colored-body panel-purple"> <div class="panel-heading"><a class="expander" href="#"><span class="fa fa-plus"></span></a> <div> <p>Summary</p> </div> </div> <div class="panel-body"> <p>Interference patterns emerge from a variety of types of coherent sources such as electromagnetic waves and sound.</p> <p>Interference can be modelled using a simulation.</p> <p style="text-align: center"><iframe allowfullscreen="" height="600" scrolling="no" src="https://phet.colorado.edu/sims/html/wave-interference/latest/wave-interference_en.html" width="800"></iframe></p> <p style="text-align: center;"><iframe height="477px" scrolling="no" src="https://tube.geogebra.org/material/iframe/id/1289123/width/603/height/477/border/888888/rc/false/ai/false/sdz/false/smb/false/stb/false/stbh/true/ld/false/sri/true/at/auto" style="border:0px;" width="603px"></iframe></p> </div> <div class="panel-footer"> <div> </div> </div> </div> <div class="panel panel-has-colored-body panel-green"> <div class="panel-heading"><a class="expander" href="#"><span class="fa fa-plus"></span></a> <div> <p>Test Yourself</p> </div> </div> <div class="panel-body"> <div> <p><em>Use quizzes to practise application of theory.</em></p> <br><a class="btn btn-primary btn-block text-center" data-toggle="modal" href="#05a58814"><i class="fa fa-play"></i> START QUIZ!</a><div class="modal fade modal-slide-quiz" id="05a58814"> <div class="modal-dialog" style="width: 95vw; max-width: 960px"> <div class="modal-content"> <div class="modal-header slide-quiz-title"> <h4 class="modal-title" style="width: 100%;"> Multiple slit interference <strong class="q-number pull-right"> <span class="counter">1</span>/<span class="total">1</span> </strong> </h4> </div> <div class="modal-body p-xs-3"> <div class="slide-quiz" data-stats="6-348-1126" style="opacity: 0"> <div class="exercise shadow-bottom"><div class="q-question"><p>The image represents the intensity distribution for the interference of light passing through N narrow slits.</p><p style="text-align: center;"><img alt="" height="231" src="../../waves/screenshot-2019-09-12-at-20.03.01.png" width="341"></p><p>What is N?</p></div><div class="q-answer"><p><label class="radio"> <input type="radio"> <span>4</span></label> </p><p><label class="radio"> <input type="radio"> <span>5</span></label> </p><p><label class="radio"> <input type="radio"> <span>3</span></label> </p><p><label class="radio"> <input class="c" type="radio"> <span>6</span></label> </p></div><div class="q-explanation"><p>The number of subsidiary maxima = N - 2</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>The image represents the intensity distribution for the interference of light passing through N narrow slits.</p><p style="text-align: center;"><img alt="" height="231" src="../../waves/screenshot-2019-09-12-at-20.03.01.png" width="341"></p>The ratio <span class="math-tex">\(\text{slit width} \over \text{slit separation}\)</span> is:</div><div class="q-answer"><p><label class="radio"> <input class="c" type="radio"> <span>0.2</span></label> </p><p><label class="radio"> <input type="radio"> <span>5</span></label> </p><p><label class="radio"> <input type="radio"> <span>4</span></label> </p><p><label class="radio"> <input type="radio"> <span>0.25</span></label> </p></div><div class="q-explanation"><p>The first diffraction minima (<span class="math-tex">\(\theta ={\lambda\over a}\)</span>) occur at the same angle as the fifth interference maxima (<span class="math-tex">\(\theta={5\lambda\over d}\)</span>).</p><p><span class="math-tex">\({\lambda\over a}={5\lambda\over d}\)</span></p><p>The ratio <span class="math-tex">\({a\over d}={1\over 5}\)</span></p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>The image represents the intensity distribution for the interference of light passing through N narrow slits.</p><p style="text-align: center;"><img alt="" height="266" src="../../waves/screenshot-2019-09-12-at-20.17.57.png" width="378"></p><p>What is the order of the fringe marked with an arrow?</p></div><div class="q-answer"><p><label class="radio"> <input type="radio"> <span>4</span></label> </p><p><label class="radio"> <input class="c" type="radio"> <span>6</span></label> </p><p><label class="radio"> <input type="radio"> <span>5</span></label> </p><p><label class="radio"> <input type="radio"> <span>3</span></label> </p></div><div class="q-explanation"><p>Fringe spacing is constant and the order is obtained by counting outward from the centre. The 4th order fringe is not visible because it falls in the diffraction minima.</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>The image represents the intensity distribution for the interference of light passing through N narrow slits.</p><p style="text-align: center;"><img alt="" height="267" src="../../waves/screenshot-2019-09-12-at-20.17.58.png" width="402"></p><p>The ratio <span class="math-tex">\(\text{slit separation}\over \text{slit width} \)</span> is:</p></div><div class="q-answer"><p><label class="radio"> <input class="c" type="radio"> <span>4</span></label> </p><p><label class="radio"> <input type="radio"> <span>0.2</span></label> </p><p><label class="radio"> <input type="radio"> <span>5</span></label> </p><p><label class="radio"> <input type="radio"> <span>0.25</span></label> </p></div><div class="q-explanation"><p>The first diffraction minima (<span class="math-tex">\(\theta ={\lambda\over a}\)</span>) occur at the same angle as the fourth interference maxima (<span class="math-tex">\(\theta={4\lambda\over d}\)</span>).</p><p><span class="math-tex">\({\lambda\over a}={4\lambda\over d}\)</span></p><p>The ratio <span class="math-tex">\({d\over a}={4\over 1}\)</span></p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>The diagram represents the intensity distribution for the same wavelength light passing through two different sets of slits.</p><p style="text-align: center;"><img alt="" height="177" src="../../waves/screenshot-2019-09-12-at-20.34.59.png" width="553"></p><p>The slits have...</p></div><div class="q-answer"><p><label class="radio"> <input type="radio"> <span>different widths and different spacing</span></label> </p><p><label class="radio"> <input type="radio"> <span>different widths but the same spacing</span></label> </p><p><label class="radio"> <input class="c" type="radio"> <span>the same width but different spacing</span></label> </p><p><label class="radio"> <input type="radio"> <span>the same width and the same spacing</span></label> </p></div><div class="q-explanation"><p>The position of the first diffraction minima are the same, which means that the slit width is unchanged. The positions of the interference maxima are different, so the spacing has changed.</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>The diagram represents the intensity distribution for the same wavelength light passing through two different sets of slits.</p><p style="text-align: center;"><img alt="" height="177" src="../../waves/screenshot-2019-09-12-at-20.34.59.png" width="553"></p><p>The ratio <span class="math-tex">\(\text{slit separation on the left} \over\text {slit separation on the right}\)</span> is:</p></div><div class="q-answer"><p><label class="radio"> <input class="c" type="radio"> <span><span class="math-tex">\(5\over4\)</span></span></label></p><p><label class="radio"> <input type="radio"> <span><span class="math-tex">\(1\)</span></span></label></p><p><label class="radio"> <input type="radio"> <span><span class="math-tex">\(4\over5\)</span></span></label></p><p><label class="radio"> <input type="radio"> <span><span class="math-tex">\(2\over3\)</span></span></label></p></div><div class="q-explanation"><p>The 5th maximum on the left has the same position as the 4th maximum on the right. The ratio of the fringe spacing is <span class="math-tex">\(4\over 5\)</span>.</p><p>Since <span class="math-tex">\(s={D\lambda\over d}\)</span>, fringe spacing is inversely proportional to slit separation.</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>The diagram represents the intensity distribution for the same wavelength light passing through two different sets of slits.</p><p style="text-align: center;"><img alt="" height="171" src="../../waves/screenshot-2019-09-13-at-04.38.27.png" width="512"></p><p>The slits have...</p></div><div class="q-answer"><p><label class="radio"> <input type="radio"> <span>the same separation but different widths</span></label> </p><p><label class="radio"> <input type="radio"> <span>the same separation and the same widths</span></label> </p><p><label class="radio"> <input class="c" type="radio"> <span>different separation but different widths</span></label> </p><p><label class="radio"> <input type="radio"> <span>different separation and the same widths</span></label> </p></div><div class="q-explanation"><p>Both fringe spacing (a result of slit separation) and the distance to the diffraction minima (a result of slit width) are different.</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>The diagram represents the intensity distribution for the same wavelength light passing through two different sets of slits.</p><p style="text-align: center;"><img alt="" height="171" src="../../waves/screenshot-2019-09-13-at-04.38.27.png" width="512"></p><p>The ratio of <span class="math-tex">\(\text{slit width}\over \text{separation}\)</span> and the number of slits in each set is:</p></div><div class="q-answer"><p><label class="radio"> <input type="radio"> <span>same - different</span></label> </p><p><label class="radio"> <input type="radio"> <span>same - same</span></label> </p><p><label class="radio"> <input type="radio"> <span>different - same</span></label> </p><p><label class="radio"> <input class="c" type="radio"> <span>different - different</span></label> </p></div><div class="q-explanation"><p>The ratio is <span class="math-tex">\(1\over 5\)</span> on the left and <span class="math-tex">\(1\over 4 \)</span> on the right.</p><p>The right set must have more slits to have narrowed the interference pattern.</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>Light of wavelength 500 nm passes through a diffraction grating with 100 lines per mm.</p><p>The angle of the 1st order maxima is:</p></div><div class="q-answer"><p><label class="radio"> <input type="radio"> <span>0.5 rad</span></label> </p><p><label class="radio"> <input type="radio"> <span>0.005 rad</span></label> </p><p><label class="radio"> <input class="c" type="radio"> <span>0.05 rad</span></label> </p><p><label class="radio"> <input type="radio"> <span>5 rad</span></label> </p></div><div class="q-explanation"><p><span class="math-tex">\(d\sinθ = nλ\Rightarrow \sin\theta={n\lambda\over d}\)</span></p><p><span class="math-tex">\(d = {1\over 100\times 10^3} = 10^{-5}\text{ m}\)</span> and <span class="math-tex">\(λ \)</span>= 5 x 10<sup>-7</sup></p><p><span class="math-tex">\(\sinθ = 0.05\)</span></p><p>This is equal to the angle in radians as the small angle approximation applies.</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>Light of two wavelengths 500 nm and 400 nm passes through a diffraction grating with 100 lines per mm.</p><p>Calculate the angular separation of the 2 different <span class="scayt-misspell-word" data-scayt-word="coloured" data-wsc-lang="en_US">coloured</span> 1st order lines</p></div><div class="q-answer"><p><label class="radio"> <input type="radio"> <span>1 rad</span></label> </p><p><label class="radio"> <input type="radio"> <span>0.1 rad</span></label> </p><p><label class="radio"> <input class="c" type="radio"> <span>0.01 rad</span></label> </p><p><label class="radio"> <input type="radio"> <span>0.001 rad</span></label> </p></div><div class="q-explanation"><p><span class="math-tex">\(d\sinθ = nλ\Rightarrow \sin\theta={n\lambda\over d}\)</span></p><p><span class="math-tex">\(d = {1\over 100\times 10^3} = 10^{-5}\text{ m}\)</span></p><p>For <span class="math-tex">\(λ\)</span> = 5 x 10<sup>-7</sup>, <span class="math-tex">\(θ = 0.05\text{ rad}\)</span></p><p>For <span class="math-tex">\(λ\)</span> = 4 x 10<sup>-7</sup>, <span class="math-tex">\(θ = 0.04 \text{ rad}\)</span></p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>A 2 mm wide laser beam is incident on a 300 line per mm grating.</p><p>What is the effective number of lines on the grating?</p></div><div class="q-answer"><p><label class="radio"> <input class="c" type="radio"> <span>600</span></label> </p><p><label class="radio"> <input type="radio"> <span>200</span></label> </p><p><label class="radio"> <input type="radio"> <span>100</span></label> </p><p><label class="radio"> <input type="radio"> <span>300</span></label> </p></div><div class="q-explanation"><p>The laser will pass through 2 x 300 lines.</p><p>NB: A longer way of answering this question would have been to calculate the slit separation and then to divide this into the width of the beam.</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>A 2 mm wide laser beam is incident on a 300 line per mm grating and used to view a 600 nm line.</p><p>What is the wavelength of the resolvable line in the first order spectrum?</p></div><div class="q-answer"><p><label class="radio"> <input class="c" type="radio"> <span>601 nm</span></label> </p><p><label class="radio"> <input type="radio"> <span>602 nm</span></label> </p><p><label class="radio"> <input type="radio"> <span>598 nm</span></label> </p><p><label class="radio"> <input type="radio"> <span>599 nm</span></label> </p></div><div class="q-explanation"><p><span class="math-tex">\(Δλ = {λ\over mN} = {600\over 600} = 1 \text{ nm}\)</span></p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>The image represents light of two wavelengths passing through a diffraction grating.</p><p style="text-align: center;"><img alt="" height="206" src="../../screenshot-2019-09-13-at-13.51.06.png" width="329"></p><p>There are 3 orders of line. Which orders can be resolved?</p></div><div class="q-answer"><p><label class="radio"> <input type="radio"> <span>1, 2 and 3</span></label> </p><p><label class="radio"> <input type="radio"> <span>Only 3</span></label> </p><p><label class="radio"> <input type="radio"> <span>1 and 2</span></label> </p><p><label class="radio"> <input class="c" type="radio"> <span>2 and 3</span></label> </p></div><div class="q-explanation"><p>Order 1 is not resolvable as the maxima are not separated sufficiently to reach the other's minimum.</p><p>Order 2 is just resolved and 3 is more easily resolved (albeit rather faint).</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>Magenta light made up of red (600 nm) and blue (400 nm) is passed through a diffraction grating producing the spectrum shown.</p><p style="text-align: center;"><img alt="" height="112" src="../../screenshot-2019-09-14-at-17.29.07.png" width="482"></p><p>Which lines are magenta?</p></div><div class="q-answer"><p><label class="radio"> <input type="radio"> <span>5</span></label> </p><p><label class="radio"> <input type="radio"> <span>2, 5 and 8</span></label> </p><p><label class="radio"> <input type="radio"> <span>3, 7 and 5</span></label> </p><p><label class="radio"> <input class="c" type="radio"> <span>1, 5 and 9</span></label> </p></div><div class="q-explanation"><p>Line 5 is the principle maximum - red and blue combine to make <strong>magenta</strong>.</p><p>Lines 4, 2 and 1, and 6, 8 and 9 are equally spaced blue light maxima.</p><p>Lines 3 and 1, and 7 and 9 are equally spaced red light maxima (more spread than blue).</p><p>Since 1 and 9 combine as both the 3rd order blue and 2nd order red, these are <strong>magenta</strong>.</p><p>NB: 600 nm is actually orange rather than red (but Chris is <span class="scayt-misspell-word" data-scayt-word="colour" data-wsc-lang="en_US">colour</span> blind!)</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>Magenta light made up of red (600 nm) and blue (400 nm) is passed through a diffraction grating producing the spectrum shown.</p><p style="text-align: center;"><img alt="" height="112" src="../../screenshot-2019-09-14-at-17.29.07.png" width="482"></p><p>Which lines are red?</p></div><div class="q-answer"><p><label class="radio"> <input type="radio"> <span>2, 4, 6 and 8</span></label> </p><p><label class="radio"> <input type="radio"> <span>2 and 8</span></label> </p><p><label class="radio"> <input type="radio"> <span>1, 3, 7 and 9</span></label> </p><p><label class="radio"> <input class="c" type="radio"> <span>3 and 7</span></label> </p></div><div class="q-explanation"><p>Line 5 is the principle maximum - red and blue combine to make magenta.</p><p>Lines 4, 2 and 1, and 6, 8 and 9 are equally spaced blue light maxima.</p><p>Lines 3 and 1, and 7 and 9 are equally spaced <strong>red</strong> light maxima (more spread than blue).</p><p><strong>BUT</strong> since 1 and 9 combine as both the 3rd order blue and 2nd order red, these are magenta.</p><p>NB: 600 nm is actually orange rather than red (but Chris is colour blind!)</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>Magenta light made up of red (600 nm) and blue (400 nm) is passed through a diffraction grating producing the spectrum shown.</p><p style="text-align: center;"><img alt="" height="112" src="../../screenshot-2019-09-14-at-17.29.07.png" width="482"></p><p>Which lines are blue?</p></div><div class="q-answer"><p><label class="radio"> <input type="radio"> <span>3, 4, 6 and 7</span></label> </p><p><label class="radio"> <input type="radio"> <span>1, 3, 7 and 9</span></label> </p><p><label class="radio"> <input class="c" type="radio"> <span>2, 4, 6 and 8</span></label> </p><p><label class="radio"> <input type="radio"> <span>1, 2, 4, 6, 8 and 9</span></label> </p></div><div class="q-explanation"><p>Line 5 is the principle maximum - red and blue combine to make magenta.</p><p>Lines 4, 2 and 1, and 6, 8 and 9 are equally spaced <strong>blue</strong> light maxima.</p><p>Lines 3 and 1, and 7 and 9 are equally spaced red light maxima (more spread than blue).</p><p><strong>BUT</strong> since 1 and 9 combine as both the 3rd order blue and 2nd order red, these are magenta.</p><p>NB: 600 nm is actually orange rather than red (but Chris is colour blind!)</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div> </div> </div> <div class="modal-footer slide-quiz-actions"> <div class=""> <div class="pull-left pull-xs-none mb-xs-3"> <button class="btn btn-default d-xs-none btn-prev"> <i class="fa fa-arrow-left"></i> Prev </button> </div> <div class="pull-right pull-xs-none"> <button class="btn btn-success btn-xs-block text-xs-center btn-results" style="display: none"> <i class="fa fa-bar-chart"></i> Check Results </button> <button class="btn btn-default d-xs-none btn-next"> Next <i class="fa fa-arrow-right"></i> </button> <button class="btn btn-default btn-xs-block text-xs-center btn-close" data-dismiss="modal" style="display: none"> Close </button> </div> </div> </div> </div> </div></div> </div> </div> <div class="panel-footer"> <div> </div> </div> </div> <div class="page-container panel-self-assessment" data-id="1126"> <div class="panel-heading">MY PROGRESS</div> <div class="panel-body understanding-rate"> <div class="msg"></div> <label class="label-lg">Self-assessment</label><p>How much of <strong>Multiple slit interference</strong> have you understood?</p><div class="slider-container text-center"><div id="self-assessment-slider" class="sib-slider self-assessment " data-value="1" data-percentage=""></div></div> <label class="label-lg">My notes</label> <textarea name="page-notes" class="form-control" rows="3" placeholder="Write your notes here..."></textarea> </div> <div class="panel-footer text-xs-center"> <span id="last-edited" class="mb-xs-3"> </span> <div class="actions mt-xs-3"> <button id="save-my-progress" type="button" class="btn btn-sm btn-primary text-center btn-xs-block"> <i class="fa fa-fw fa-floppy-o"></i> Save </button> </div> </div></div> <div id="modal-feedback" class="modal fade" tabindex="-1" role="dialog"> <div class="modal-dialog" role="document"> <div class="modal-content"> <div class="modal-header"> <h4 class="modal-title">Feedback</h4> <button type="button" class="close hidden-xs hidden-sm" data-dismiss="modal" aria-label="Close"> <span aria-hidden="true">×</span> </button> </div> <div class="modal-body"> <div class="errors"></div> <p><strong>Which of the following best describes your feedback?</strong></p> <form method="post" style="overflow: hidden"> <div class="form-group"> <div class="radio"><label style="color: #121212;"><input type="radio" name="feedback-type" value="Recommendation"> Recommend</label></div><div class="radio"><label style="color: #121212;"><input type="radio" name="feedback-type" value="Problem"> Report a problem</label></div><div class="radio"><label style="color: #121212;"><input type="radio" name="feedback-type" value="Improvement"> Suggest an improvement</label></div><div class="radio"><label style="color: #121212;"><input type="radio" name="feedback-type" value="Other"> Other</label></div> </div> <hr> <div class="row"> <div class="col-md-6"> <div class="form-group"> <label for="feedback-name">Name</label> <input type="text" class="form-control" name="feedback-name" placeholder="Name" value=" "> </div> </div> <div class="col-md-6"> <div class="form-group"> <label for="feedback-email">Email address</label> <input type="email" class="form-control" name="feedback-email" placeholder="Email" value="@airmail.cc"> </div> </div> </div> <div class="form-group"> <label for="feedback-comments">Comments</label> <textarea class="form-control" name="feedback-comments" style="resize: vertical;"></textarea> </div> <input type="hidden" name="feedback-ticket" value="082b9c9c4ae3624d"> <input type="hidden" name="feedback-url" value="https://studyib.net/physics/page/1126/multiple-slit-interference"> <input type="hidden" name="feedback-subject" value="6"> <input type="hidden" name="feedback-subject-name" value="Physics"> <div class="pull-left"> </div> </form> </div> <div class="modal-footer"> <button type="button" class="btn btn-primary btn-xs-block feedback-submit mb-xs-3 pull-right"> <i class="fa fa-send"></i> Send </button> <button type="button" class="btn btn-default btn-xs-block m-xs-0 pull-left" data-dismiss="modal"> Close </button> </div> </div> </div></div> </article> <hr class="hidden-md hidden-lg"> <div class="hidden-md hidden-lg mt-xs-3"> <button class="btn btn-default btn-block text-xs-center" data-toggle="modal" data-target="#modal-feedback" style="margin-bottom: 10px"><i class="fa fa-send"></i> Feedback</button> </div> </div> <input type="hidden" id="user-id" value="38342"></div><input id="ticket" type="hidden" value="082b9c9c4ae3624d"><input id="tzoffset" type="hidden" value="new"><input id="fp" class="fp" type="hidden" value=""></div><div id="std-footer"> <div class="wmap"> <div class="layout-wrapper"> <p> <a href="https://www.inthinking.net"> © <span id="footer-year"></span> <em>InThinking</em> <script>document.getElementById("footer-year").innerHTML = new Date().getFullYear();</script> </a> | <a target="_self" href="../../../about.html"> About us </a> | <a target="_self" href="../../../terms-and-conditions.html"> Legal </a> | <a target="_self" href="../../../contact.html"> Contact </a> </p> <p> <a class="social" target="_blank" href="https://twitter.com/#!/inthinker"> <img src="../../../img/social/twitter-square.svg"> Twitter </a> <a class="social" target="_blank" href="https://www.facebook.com/inthinking.net"> <img src="../../../img/social/facebook-square.svg"> Facebook </a> <a class="social" target="_blank" href="https://www.linkedin.com/profile/view?id=139741989"> <img src="../../../img/social/linkedin-square.svg"> LinkedIn </a> </p> </div> </div></div><script src="../../../js/jquery-1.11.3.min.js"></script><script src="../../../js/bootstrap.min.js"></script><script src="../../../js/jquery-fancybox/jquery.fancybox.min.js"></script><script>var pageId = 1126;</script><script type="text/javascript" src="../../../js/jqueryui/jquery-ui-custom.min.js"></script><script type="text/javascript" src="../../../js/jqueryui/jquery.ui.touch-punch.js"></script><script type="text/javascript" src="../../../js/std-quizzes-helpers.min.js?v=20220406"></script><script src="../../../ajax/libs/mathjax/2.7.0/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script><script type="text/javascript" src="../../../js/slick-carousel/slick.min.js"></script><script type="text/javascript" src="../../../js/std-slide-quizzes.min.js?v=20220406"></script><script type="text/javascript" src="../../../js/jqueryui/jquery-ui.min.js"></script><script type="text/javascript" src="../../../js/jqueryui/jquery.ui.touch-punch.min.js"></script><script src="../../../js/user/page-my-progress.min.js?v=202211221000"></script><script>var sAJAX='/pages/subjects/activity/user-stats-page.php?t=082b9c9c4ae3624d&p=1126&s=6&x=18130';var sData='k4iA6GSB03BgPm1yOUP3IxiA6GSB0bfq7Y9FwFiA6GSBPFAF7YcHEKvrZ0fREzP5PgLLWVfj7YyBPVaRZ0ClZGqrE0inE0iBWnaBPFAF7YcHEKvr6GSDPmjoPnyBSnKR74P5GDaSezAFWGcrE0ij6GyDPmjn6GyDEzAF7bKFEYv86GB2Pm1FPFAF7YcrZxP5PBAh7Ysq73Bm7LAh7YcHEKAhOUu4aBAhW0KRSYBAWY9873yjSxLjWHfB7nEB7nK2639FeC==';var loopSecs = 30;var minSecsLog = 60;var lsKey = '6-83610-1126';</script><script src="../../../js/subjects/activity/user-stats-page.min.js?v=202205311700"></script><script src="../../../js/subjects/activity/my-favorites.min.js?v=20220610"></script><script src="../../../js/subjects/feedback.min.js?v=202211221000"></script><script>var sessionUpdateSecs = 300;</script><script type="text/javascript" src="../../../js/session-updater.js"></script><script>(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)})(window,document,'script','https://www.google-analytics.com/analytics.js','ga');ga('create', 'UA-98480796-3', 'auto');ga('send', 'pageview');</script><script src="../../../js/devicefp/devicefp.min.js"></script><script src="../../../js/jq-quickfit/jq-quickfit.min.js?v=20220201"></script><script src="../../../js/frontpage-subjects.min.js?v=202211161300"></script><script type="text/javascript" src="../../../js/studyib-jq.min.js?v=202211241300"></script><script type="text/javascript">$(document).ready(function(){ $('#trigger-modal-video-overview').click(function() { if( $('#modal-video-overview .modal-body iframe').attr('src').length == 0 ) { $('#modal-video-overview .modal-body iframe').attr('src', 'https://www.youtube.com/embed/hxxtdiLdTFk?rel=0'); } }); $('#modal-video-overview').on('hidden.bs.modal', function() { $('#modal-video-overview .modal-body iframe').attr('src', ''); }); });</script></body></html>