<div class="xblock xblock-public_view xblock-public_view-vertical" data-runtime-class="LmsRuntime" data-usage-id="block-v1:MITx+3.15.2x+2T2017+type@vertical+block@e52c7a733c9e4be399ce0662d20ea68b" data-init="VerticalStudentView" data-runtime-version="1" data-course-id="course-v1:MITx+3.15.2x+2T2017" data-block-type="vertical" data-has-score="False" data-graded="False" data-request-token="fdee7f3e020811ef9d0216fff75c5923">
<h2 class="hd hd-2 unit-title">Organic Electronics</h2>
<div class="vert-mod">
<div class="vert vert-0" data-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@d690e06013fc4f04b24fef49edb56e27">
<div class="xblock xblock-public_view xblock-public_view-problem xmodule_display xmodule_ProblemBlock" data-runtime-class="LmsRuntime" data-usage-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@d690e06013fc4f04b24fef49edb56e27" data-init="XBlockToXModuleShim" data-runtime-version="1" data-course-id="course-v1:MITx+3.15.2x+2T2017" data-block-type="problem" data-has-score="True" data-graded="False" data-request-token="fdee7f3e020811ef9d0216fff75c5923">
<script type="json/xblock-args" class="xblock-json-init-args">
{"xmodule-type": "Problem"}
</script>
<div id="problem_d690e06013fc4f04b24fef49edb56e27" class="problems-wrapper" role="group"
aria-labelledby="d690e06013fc4f04b24fef49edb56e27-problem-title"
data-problem-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@d690e06013fc4f04b24fef49edb56e27" data-url="/courses/course-v1:MITx+3.15.2x+2T2017/xblock/block-v1:MITx+3.15.2x+2T2017+type@problem+block@d690e06013fc4f04b24fef49edb56e27/handler/xmodule_handler"
data-problem-score="0"
data-problem-total-possible="21"
data-attempts-used="0"
data-content="
<h3 class="hd hd-3 problem-header" id="d690e06013fc4f04b24fef49edb56e27-problem-title" aria-describedby="block-v1:MITx+3.15.2x+2T2017+type@problem+block@d690e06013fc4f04b24fef49edb56e27-problem-progress" tabindex="-1">
Organic Electronics
</h3>
<div class="problem-progress" id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@d690e06013fc4f04b24fef49edb56e27-problem-progress"></div>
<div class="problem">
<div>
<h1>Exercise 3.1A</h1>
<p>
Review the lectures on Organic Electronics. Then complete the following statements by selecting the correct terms from the dropdown menu. </p>
<div class="wrapper-problem-response" tabindex="-1" aria-label="Question 1" role="group"><div class="multi-inputs-group" role="group"><p style="display:inline">1) Organic materials with lots of alternating double and single bonds can conduct electricity. Electron conduction occurs through the </p>
<div class="inputtype option-input inline">
<select name="input_d690e06013fc4f04b24fef49edb56e27_2_1" id="input_d690e06013fc4f04b24fef49edb56e27_2_1" aria-describedby="status_d690e06013fc4f04b24fef49edb56e27_2_1">
<option value="option_d690e06013fc4f04b24fef49edb56e27_2_1_dummy_default">Select an option</option>
<option value="band gap"> band gap</option>
<option value="bilayer"> bilayer</option>
<option value="delocalized pi"> delocalized pi</option>
<option value="electric field"> electric field</option>
<option value="exciton"> exciton</option>
<option value="n-type layer"> n-type layer</option>
<option value="p-type layer"> p-type layer</option>
<option value="polymers"> polymers</option>
<option value="small molecules"> small molecules</option>
<option value="tunnel"> tunnel</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_d690e06013fc4f04b24fef49edb56e27_2_1" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_d690e06013fc4f04b24fef49edb56e27_2_1"/>
</div><p style="display:inline">electrons of these conjugated structures.</p>
<br/>
<br/>
<p style="display:inline">2) Electrons can</p>
<div class="inputtype option-input inline">
<select name="input_d690e06013fc4f04b24fef49edb56e27_2_2" id="input_d690e06013fc4f04b24fef49edb56e27_2_2" aria-describedby="status_d690e06013fc4f04b24fef49edb56e27_2_2">
<option value="option_d690e06013fc4f04b24fef49edb56e27_2_2_dummy_default">Select an option</option>
<option value="band gap"> band gap</option>
<option value="bilayer"> bilayer</option>
<option value="delocalized pi"> delocalized pi</option>
<option value="electric field"> electric field</option>
<option value="exciton"> exciton</option>
<option value="n-type layer"> n-type layer</option>
<option value="p-type layer"> p-type layer</option>
<option value="polymers"> polymers</option>
<option value="small molecules"> small molecules</option>
<option value="tunnel"> tunnel</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_d690e06013fc4f04b24fef49edb56e27_2_2" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_d690e06013fc4f04b24fef49edb56e27_2_2"/>
</div><p style="display:inline">, from one organic molecule to the next, giving conductivity across the whole material, rather than just within a single molecule.</p>
<br/>
<br/>
<p style="display:inline">3) The carrier mobilities within conducting polymers are typically </p>
<div class="inputtype option-input inline">
<select name="input_d690e06013fc4f04b24fef49edb56e27_2_3" id="input_d690e06013fc4f04b24fef49edb56e27_2_3" aria-describedby="status_d690e06013fc4f04b24fef49edb56e27_2_3">
<option value="option_d690e06013fc4f04b24fef49edb56e27_2_3_dummy_default">Select an option</option>
<option value="low"> low</option>
<option value="moderate"> moderate</option>
<option value="high"> high</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_d690e06013fc4f04b24fef49edb56e27_2_3" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_d690e06013fc4f04b24fef49edb56e27_2_3"/>
</div><p style="display:inline">Rubrene (an excellent organic semiconductor), has a mobility of </p>
<div class="inputtype option-input inline">
<select name="input_d690e06013fc4f04b24fef49edb56e27_2_4" id="input_d690e06013fc4f04b24fef49edb56e27_2_4" aria-describedby="status_d690e06013fc4f04b24fef49edb56e27_2_4">
<option value="option_d690e06013fc4f04b24fef49edb56e27_2_4_dummy_default">Select an option</option>
<option value="1"> 1</option>
<option value="20-40"> 20-40</option>
<option value="450"> 450</option>
<option value="1500"> 1500</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_d690e06013fc4f04b24fef49edb56e27_2_4" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_d690e06013fc4f04b24fef49edb56e27_2_4"/>
</div><p style="display:inline">\(cm^2/V \cdot s\), and mobilities of </p>
<div class="inputtype option-input inline">
<select name="input_d690e06013fc4f04b24fef49edb56e27_2_5" id="input_d690e06013fc4f04b24fef49edb56e27_2_5" aria-describedby="status_d690e06013fc4f04b24fef49edb56e27_2_5">
<option value="option_d690e06013fc4f04b24fef49edb56e27_2_5_dummy_default">Select an option</option>
<option value="1"> 1</option>
<option value="20-40 "> 20-40 </option>
<option value="450"> 450</option>
<option value="1500"> 1500</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_d690e06013fc4f04b24fef49edb56e27_2_5" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_d690e06013fc4f04b24fef49edb56e27_2_5"/>
</div><p style="display:inline">\(cm^2/V \cdot s\) are not atypical. You can compare this to silicon, with an electron mobility of about </p>
<div class="inputtype option-input inline">
<select name="input_d690e06013fc4f04b24fef49edb56e27_2_6" id="input_d690e06013fc4f04b24fef49edb56e27_2_6" aria-describedby="status_d690e06013fc4f04b24fef49edb56e27_2_6">
<option value="option_d690e06013fc4f04b24fef49edb56e27_2_6_dummy_default">Select an option</option>
<option value="1"> 1</option>
<option value="20-40 "> 20-40 </option>
<option value="450"> 450</option>
<option value="1500"> 1500</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_d690e06013fc4f04b24fef49edb56e27_2_6" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_d690e06013fc4f04b24fef49edb56e27_2_6"/>
</div><p style="display:inline">\(cm^2/V \cdot s\) and a hole mobility of around</p>
<div class="inputtype option-input inline">
<select name="input_d690e06013fc4f04b24fef49edb56e27_2_7" id="input_d690e06013fc4f04b24fef49edb56e27_2_7" aria-describedby="status_d690e06013fc4f04b24fef49edb56e27_2_7">
<option value="option_d690e06013fc4f04b24fef49edb56e27_2_7_dummy_default">Select an option</option>
<option value="1"> 1</option>
<option value="20-40 "> 20-40 </option>
<option value="450"> 450</option>
<option value="1500"> 1500</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_d690e06013fc4f04b24fef49edb56e27_2_7" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_d690e06013fc4f04b24fef49edb56e27_2_7"/>
</div><p style="display:inline">\(cm^2/V \cdot s\).</p>
<br/>
<br/>
<p style="display:inline">4) Conducting organics can be made from either polymers or from small molecules, though the fabrication approach tends to be different. </p>
<div class="inputtype option-input inline">
<select name="input_d690e06013fc4f04b24fef49edb56e27_2_8" id="input_d690e06013fc4f04b24fef49edb56e27_2_8" aria-describedby="status_d690e06013fc4f04b24fef49edb56e27_2_8">
<option value="option_d690e06013fc4f04b24fef49edb56e27_2_8_dummy_default">Select an option</option>
<option value="band gap"> band gap</option>
<option value="bilayer"> bilayer</option>
<option value="delocalized pi"> delocalized pi</option>
<option value="electric field"> electric field</option>
<option value="exciton"> exciton</option>
<option value="n-type layer"> n-type layer</option>
<option value="p-type layer"> p-type layer</option>
<option value="polymers"> polymers</option>
<option value="small molecules"> small molecules</option>
<option value="tunnel"> tunnel</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_d690e06013fc4f04b24fef49edb56e27_2_8" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_d690e06013fc4f04b24fef49edb56e27_2_8"/>
</div><p style="display:inline">can be evaporated onto a surface to make a thin film, while </p>
<div class="inputtype option-input inline">
<select name="input_d690e06013fc4f04b24fef49edb56e27_2_9" id="input_d690e06013fc4f04b24fef49edb56e27_2_9" aria-describedby="status_d690e06013fc4f04b24fef49edb56e27_2_9">
<option value="option_d690e06013fc4f04b24fef49edb56e27_2_9_dummy_default">Select an option</option>
<option value="band gap"> band gap</option>
<option value="bilayer"> bilayer</option>
<option value="delocalized pi"> delocalized pi</option>
<option value="electric field"> electric field</option>
<option value="exciton"> exciton</option>
<option value="n-type layer"> n-type layer</option>
<option value="p-type layer"> p-type layer</option>
<option value="polymers"> polymers</option>
<option value="small molecules"> small molecules</option>
<option value="tunnel"> tunnel</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_d690e06013fc4f04b24fef49edb56e27_2_9" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_d690e06013fc4f04b24fef49edb56e27_2_9"/>
</div><p style="display:inline">are usually spin coated.</p>
<br/>
<br/>
<p style="display:inline">5) The </p>
<div class="inputtype option-input inline">
<select name="input_d690e06013fc4f04b24fef49edb56e27_2_10" id="input_d690e06013fc4f04b24fef49edb56e27_2_10" aria-describedby="status_d690e06013fc4f04b24fef49edb56e27_2_10">
<option value="option_d690e06013fc4f04b24fef49edb56e27_2_10_dummy_default">Select an option</option>
<option value="band gap"> band gap</option>
<option value="bilayer"> bilayer</option>
<option value="delocalized pi"> delocalized pi</option>
<option value="electric field"> electric field</option>
<option value="exciton"> exciton</option>
<option value="n-type layer"> n-type layer</option>
<option value="p-type layer"> p-type layer</option>
<option value="polymers"> polymers</option>
<option value="small molecules"> small molecules</option>
<option value="tunnel"> tunnel</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_d690e06013fc4f04b24fef49edb56e27_2_10" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_d690e06013fc4f04b24fef49edb56e27_2_10"/>
</div><p style="display:inline">of organic semiconductors is tuned by adjusting the structure of the molecule.</p>
<br/>
<br/>
<b>Organic Photovoltaics:</b>
<br/>
<br/>
<p style="display:inline">6) When an organic semiconductor absorbs a photon, an </p>
<div class="inputtype option-input inline">
<select name="input_d690e06013fc4f04b24fef49edb56e27_2_11" id="input_d690e06013fc4f04b24fef49edb56e27_2_11" aria-describedby="status_d690e06013fc4f04b24fef49edb56e27_2_11">
<option value="option_d690e06013fc4f04b24fef49edb56e27_2_11_dummy_default">Select an option</option>
<option value="band gap"> band gap</option>
<option value="bilayer"> bilayer</option>
<option value="delocalized pi"> delocalized pi</option>
<option value="electric field"> electric field</option>
<option value="exciton"> exciton</option>
<option value="n-type layer"> n-type layer</option>
<option value="p-type layer"> p-type layer</option>
<option value="polymers"> polymers</option>
<option value="small molecules"> small molecules</option>
<option value="tunnel"> tunnel</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_d690e06013fc4f04b24fef49edb56e27_2_11" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_d690e06013fc4f04b24fef49edb56e27_2_11"/>
</div><p style="display:inline">is typically formed, which can be split apart by an </p>
<div class="inputtype option-input inline">
<select name="input_d690e06013fc4f04b24fef49edb56e27_2_12" id="input_d690e06013fc4f04b24fef49edb56e27_2_12" aria-describedby="status_d690e06013fc4f04b24fef49edb56e27_2_12">
<option value="option_d690e06013fc4f04b24fef49edb56e27_2_12_dummy_default">Select an option</option>
<option value="band gap"> band gap</option>
<option value="bilayer"> bilayer</option>
<option value="delocalized pi"> delocalized pi</option>
<option value="electric field"> electric field</option>
<option value="exciton"> exciton</option>
<option value="n-type layer"> n-type layer</option>
<option value="p-type layer"> p-type layer</option>
<option value="polymers"> polymers</option>
<option value="small molecules"> small molecules</option>
<option value="tunnel"> tunnel</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_d690e06013fc4f04b24fef49edb56e27_2_12" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_d690e06013fc4f04b24fef49edb56e27_2_12"/>
</div><p style="display:inline">, causing the electrons to move in one direction, and the holes to move in the other.</p>
<br/>
<br/>
<p style="display:inline">7) To make an organic photovoltaic, we use a </p>
<div class="inputtype option-input inline">
<select name="input_d690e06013fc4f04b24fef49edb56e27_2_13" id="input_d690e06013fc4f04b24fef49edb56e27_2_13" aria-describedby="status_d690e06013fc4f04b24fef49edb56e27_2_13">
<option value="option_d690e06013fc4f04b24fef49edb56e27_2_13_dummy_default">Select an option</option>
<option value="band gap"> band gap</option>
<option value="bilayer"> bilayer</option>
<option value="delocalized pi"> delocalized pi</option>
<option value="electric field"> electric field</option>
<option value="exciton"> exciton</option>
<option value="n-type layer"> n-type layer</option>
<option value="p-type layer"> p-type layer</option>
<option value="polymers"> polymers</option>
<option value="small molecules"> small molecules</option>
<option value="tunnel"> tunnel</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_d690e06013fc4f04b24fef49edb56e27_2_13" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_d690e06013fc4f04b24fef49edb56e27_2_13"/>
</div><p style="display:inline">structure, where holes are transported in a </p>
<div class="inputtype option-input inline">
<select name="input_d690e06013fc4f04b24fef49edb56e27_2_14" id="input_d690e06013fc4f04b24fef49edb56e27_2_14" aria-describedby="status_d690e06013fc4f04b24fef49edb56e27_2_14">
<option value="option_d690e06013fc4f04b24fef49edb56e27_2_14_dummy_default">Select an option</option>
<option value="band gap"> band gap</option>
<option value="bilayer"> bilayer</option>
<option value="delocalized pi"> delocalized pi</option>
<option value="electric field"> electric field</option>
<option value="exciton"> exciton</option>
<option value="n-type layer"> n-type layer</option>
<option value="p-type layer"> p-type layer</option>
<option value="polymers"> polymers</option>
<option value="small molecules"> small molecules</option>
<option value="tunnel"> tunnel</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_d690e06013fc4f04b24fef49edb56e27_2_14" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_d690e06013fc4f04b24fef49edb56e27_2_14"/>
</div><p style="display:inline">, and electrons are transported in an </p>
<div class="inputtype option-input inline">
<select name="input_d690e06013fc4f04b24fef49edb56e27_2_15" id="input_d690e06013fc4f04b24fef49edb56e27_2_15" aria-describedby="status_d690e06013fc4f04b24fef49edb56e27_2_15">
<option value="option_d690e06013fc4f04b24fef49edb56e27_2_15_dummy_default">Select an option</option>
<option value="band gap"> band gap</option>
<option value="bilayer"> bilayer</option>
<option value="delocalized pi"> delocalized pi</option>
<option value="electric field"> electric field</option>
<option value="exciton"> exciton</option>
<option value="n-type layer"> n-type layer</option>
<option value="p-type layer"> p-type layer</option>
<option value="polymers"> polymers</option>
<option value="small molecules"> small molecules</option>
<option value="tunnel"> tunnel</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_d690e06013fc4f04b24fef49edb56e27_2_15" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_d690e06013fc4f04b24fef49edb56e27_2_15"/>
</div><br/>
<br/>
<b>Organic LEDs:</b>
<br/>
<br/>
<p style="display:inline">8) In the case of an organic LED, we inject electrons and holes from opposing electrodes. Holes are injected by a </p>
<div class="inputtype option-input inline">
<select name="input_d690e06013fc4f04b24fef49edb56e27_2_16" id="input_d690e06013fc4f04b24fef49edb56e27_2_16" aria-describedby="status_d690e06013fc4f04b24fef49edb56e27_2_16">
<option value="option_d690e06013fc4f04b24fef49edb56e27_2_16_dummy_default">Select an option</option>
<option value="low work function"> low work function</option>
<option value="high work function"> high work function</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_d690e06013fc4f04b24fef49edb56e27_2_16" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_d690e06013fc4f04b24fef49edb56e27_2_16"/>
</div><p style="display:inline">electrode, and electrons are injected by a</p>
<div class="inputtype option-input inline">
<select name="input_d690e06013fc4f04b24fef49edb56e27_2_17" id="input_d690e06013fc4f04b24fef49edb56e27_2_17" aria-describedby="status_d690e06013fc4f04b24fef49edb56e27_2_17">
<option value="option_d690e06013fc4f04b24fef49edb56e27_2_17_dummy_default">Select an option</option>
<option value="low work function"> low work function</option>
<option value="high work function"> high work function</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_d690e06013fc4f04b24fef49edb56e27_2_17" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_d690e06013fc4f04b24fef49edb56e27_2_17"/>
</div><p style="display:inline">electrode.</p>
<br/>
<br/>
<p> 9) These electrons and holes recombine via excitons.</p>
<p style="display:inline">10) There are two types of excitons: triplets and singlets. In a signlet exciton, the electron and hole have the </p>
<div class="inputtype option-input inline">
<select name="input_d690e06013fc4f04b24fef49edb56e27_2_18" id="input_d690e06013fc4f04b24fef49edb56e27_2_18" aria-describedby="status_d690e06013fc4f04b24fef49edb56e27_2_18">
<option value="option_d690e06013fc4f04b24fef49edb56e27_2_18_dummy_default">Select an option</option>
<option value="opposite"> opposite</option>
<option value="same"> same</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_d690e06013fc4f04b24fef49edb56e27_2_18" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_d690e06013fc4f04b24fef49edb56e27_2_18"/>
</div><p style="display:inline">spin. In a triplet, the electron and hole have the </p>
<div class="inputtype option-input inline">
<select name="input_d690e06013fc4f04b24fef49edb56e27_2_19" id="input_d690e06013fc4f04b24fef49edb56e27_2_19" aria-describedby="status_d690e06013fc4f04b24fef49edb56e27_2_19">
<option value="option_d690e06013fc4f04b24fef49edb56e27_2_19_dummy_default">Select an option</option>
<option value="opposite"> opposite</option>
<option value="same"> same</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_d690e06013fc4f04b24fef49edb56e27_2_19" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_d690e06013fc4f04b24fef49edb56e27_2_19"/>
</div><p style="display:inline">spin.</p>
<br/>
<br/>
<p style="display:inline">11) Only singlets contribute to photon creation in our LED. For every singlet produced, </p>
<div class="inputtype option-input inline">
<select name="input_d690e06013fc4f04b24fef49edb56e27_2_20" id="input_d690e06013fc4f04b24fef49edb56e27_2_20" aria-describedby="status_d690e06013fc4f04b24fef49edb56e27_2_20">
<option value="option_d690e06013fc4f04b24fef49edb56e27_2_20_dummy_default">Select an option</option>
<option value="one"> one</option>
<option value="two"> two</option>
<option value="three"> three</option>
<option value="four"> four</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_d690e06013fc4f04b24fef49edb56e27_2_20" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_d690e06013fc4f04b24fef49edb56e27_2_20"/>
</div><p style="display:inline"> triplets are formed. This means that no more than </p>
<div class="inputtype option-input inline">
<select name="input_d690e06013fc4f04b24fef49edb56e27_2_21" id="input_d690e06013fc4f04b24fef49edb56e27_2_21" aria-describedby="status_d690e06013fc4f04b24fef49edb56e27_2_21">
<option value="option_d690e06013fc4f04b24fef49edb56e27_2_21_dummy_default">Select an option</option>
<option value="15"> 15</option>
<option value="25"> 25</option>
<option value="50"> 50</option>
<option value="75"> 75</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_d690e06013fc4f04b24fef49edb56e27_2_21" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_d690e06013fc4f04b24fef49edb56e27_2_21"/>
</div><p style="display:inline">percent of the carriers injected into our organic material are able to generate photons.</p>
</div></div>
</div>
<div class="action">
<input type="hidden" name="problem_id" value="Organic Electronics" />
<div class="submit-attempt-container">
<button type="button" class="submit btn-brand" data-submitting="Submitting" data-value="Submit" data-should-enable-submit-button="True" aria-describedby="submission_feedback_d690e06013fc4f04b24fef49edb56e27" >
<span class="submit-label">Submit</span>
</button>
<div class="submission-feedback" id="submission_feedback_d690e06013fc4f04b24fef49edb56e27">
<span class="sr">Some problems have options such as save, reset, hints, or show answer. These options follow the Submit button.</span>
</div>
</div>
<div class="problem-action-buttons-wrapper">
</div>
</div>
<div class="notification warning notification-gentle-alert
is-hidden"
tabindex="-1">
<span class="icon fa fa-exclamation-circle" aria-hidden="true"></span>
<span class="notification-message" aria-describedby="d690e06013fc4f04b24fef49edb56e27-problem-title">
</span>
<div class="notification-btn-wrapper">
<button type="button" class="btn btn-default btn-small notification-btn review-btn sr">Review</button>
</div>
</div>
<div class="notification warning notification-save
is-hidden"
tabindex="-1">
<span class="icon fa fa-save" aria-hidden="true"></span>
<span class="notification-message" aria-describedby="d690e06013fc4f04b24fef49edb56e27-problem-title">None
</span>
<div class="notification-btn-wrapper">
<button type="button" class="btn btn-default btn-small notification-btn review-btn sr">Review</button>
</div>
</div>
<div class="notification general notification-show-answer
is-hidden"
tabindex="-1">
<span class="icon fa fa-info-circle" aria-hidden="true"></span>
<span class="notification-message" aria-describedby="d690e06013fc4f04b24fef49edb56e27-problem-title">Answers are displayed within the problem
</span>
<div class="notification-btn-wrapper">
<button type="button" class="btn btn-default btn-small notification-btn review-btn sr">Review</button>
</div>
</div>
</div>
"
data-graded="False">
<p class="loading-spinner">
<i class="fa fa-spinner fa-pulse fa-2x fa-fw"></i>
<span class="sr">Loading…</span>
</p>
</div>
</div>
</div>
<div class="vert vert-1" data-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@f2621794175a4d95b035b1d08d191787">
<div class="xblock xblock-public_view xblock-public_view-problem xmodule_display xmodule_ProblemBlock" data-runtime-class="LmsRuntime" data-usage-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@f2621794175a4d95b035b1d08d191787" data-init="XBlockToXModuleShim" data-runtime-version="1" data-course-id="course-v1:MITx+3.15.2x+2T2017" data-block-type="problem" data-has-score="True" data-graded="False" data-request-token="fdee7f3e020811ef9d0216fff75c5923">
<script type="json/xblock-args" class="xblock-json-init-args">
{"xmodule-type": "Problem"}
</script>
<div id="problem_f2621794175a4d95b035b1d08d191787" class="problems-wrapper" role="group"
aria-labelledby="f2621794175a4d95b035b1d08d191787-problem-title"
data-problem-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@f2621794175a4d95b035b1d08d191787" data-url="/courses/course-v1:MITx+3.15.2x+2T2017/xblock/block-v1:MITx+3.15.2x+2T2017+type@problem+block@f2621794175a4d95b035b1d08d191787/handler/xmodule_handler"
data-problem-score="0"
data-problem-total-possible="1"
data-attempts-used="0"
data-content="
<h3 class="hd hd-3 problem-header" id="f2621794175a4d95b035b1d08d191787-problem-title" aria-describedby="block-v1:MITx+3.15.2x+2T2017+type@problem+block@f2621794175a4d95b035b1d08d191787-problem-progress" tabindex="-1">
Exercise 3.1B
</h3>
<div class="problem-progress" id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@f2621794175a4d95b035b1d08d191787-problem-progress"></div>
<div class="problem">
<div>
<p>Which of the following molecules are conducting organics?</p>
<img src="/assets/courseware/v1/bc0423c8c1b9dd54d07a78614d5039be/asset-v1:MITx+3.15.2x+2T2017+type@asset+block/315ConjugatedPolymers.jpg" alt="A) Chain of benzene rings B) Polymer with alternating double and single bonds C) Polymer with single bonds only D) Complex structure of benzene rings " width="500"/>
<div class="wrapper-problem-response" tabindex="-1" aria-label="Question 1" role="group"><div class="choicegroup capa_inputtype" id="inputtype_f2621794175a4d95b035b1d08d191787_2_1">
<fieldset aria-describedby="status_f2621794175a4d95b035b1d08d191787_2_1">
<div class="field">
<input type="checkbox" name="input_f2621794175a4d95b035b1d08d191787_2_1[]" id="input_f2621794175a4d95b035b1d08d191787_2_1_choice_0" class="field-input input-checkbox" value="choice_0"/><label id="f2621794175a4d95b035b1d08d191787_2_1-choice_0-label" for="input_f2621794175a4d95b035b1d08d191787_2_1_choice_0" class="response-label field-label label-inline" aria-describedby="status_f2621794175a4d95b035b1d08d191787_2_1"> Molecule A
</label>
</div>
<div class="field">
<input type="checkbox" name="input_f2621794175a4d95b035b1d08d191787_2_1[]" id="input_f2621794175a4d95b035b1d08d191787_2_1_choice_1" class="field-input input-checkbox" value="choice_1"/><label id="f2621794175a4d95b035b1d08d191787_2_1-choice_1-label" for="input_f2621794175a4d95b035b1d08d191787_2_1_choice_1" class="response-label field-label label-inline" aria-describedby="status_f2621794175a4d95b035b1d08d191787_2_1"> Molecule B
</label>
</div>
<div class="field">
<input type="checkbox" name="input_f2621794175a4d95b035b1d08d191787_2_1[]" id="input_f2621794175a4d95b035b1d08d191787_2_1_choice_2" class="field-input input-checkbox" value="choice_2"/><label id="f2621794175a4d95b035b1d08d191787_2_1-choice_2-label" for="input_f2621794175a4d95b035b1d08d191787_2_1_choice_2" class="response-label field-label label-inline" aria-describedby="status_f2621794175a4d95b035b1d08d191787_2_1"> Molecule C
</label>
</div>
<div class="field">
<input type="checkbox" name="input_f2621794175a4d95b035b1d08d191787_2_1[]" id="input_f2621794175a4d95b035b1d08d191787_2_1_choice_3" class="field-input input-checkbox" value="choice_3"/><label id="f2621794175a4d95b035b1d08d191787_2_1-choice_3-label" for="input_f2621794175a4d95b035b1d08d191787_2_1_choice_3" class="response-label field-label label-inline" aria-describedby="status_f2621794175a4d95b035b1d08d191787_2_1"> Molecule D
</label>
</div>
<span id="answer_f2621794175a4d95b035b1d08d191787_2_1"/>
</fieldset>
<div class="indicator-container">
<span class="status unanswered" id="status_f2621794175a4d95b035b1d08d191787_2_1" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
</div></div>
<div class="solution-span">
<span id="solution_f2621794175a4d95b035b1d08d191787_solution_1"/>
</div></div>
<div class="action">
<input type="hidden" name="problem_id" value="Exercise 3.1B" />
<div class="submit-attempt-container">
<button type="button" class="submit btn-brand" data-submitting="Submitting" data-value="Submit" data-should-enable-submit-button="True" aria-describedby="submission_feedback_f2621794175a4d95b035b1d08d191787" >
<span class="submit-label">Submit</span>
</button>
<div class="submission-feedback" id="submission_feedback_f2621794175a4d95b035b1d08d191787">
<span class="sr">Some problems have options such as save, reset, hints, or show answer. These options follow the Submit button.</span>
</div>
</div>
<div class="problem-action-buttons-wrapper">
</div>
</div>
<div class="notification warning notification-gentle-alert
is-hidden"
tabindex="-1">
<span class="icon fa fa-exclamation-circle" aria-hidden="true"></span>
<span class="notification-message" aria-describedby="f2621794175a4d95b035b1d08d191787-problem-title">
</span>
<div class="notification-btn-wrapper">
<button type="button" class="btn btn-default btn-small notification-btn review-btn sr">Review</button>
</div>
</div>
<div class="notification warning notification-save
is-hidden"
tabindex="-1">
<span class="icon fa fa-save" aria-hidden="true"></span>
<span class="notification-message" aria-describedby="f2621794175a4d95b035b1d08d191787-problem-title">None
</span>
<div class="notification-btn-wrapper">
<button type="button" class="btn btn-default btn-small notification-btn review-btn sr">Review</button>
</div>
</div>
<div class="notification general notification-show-answer
is-hidden"
tabindex="-1">
<span class="icon fa fa-info-circle" aria-hidden="true"></span>
<span class="notification-message" aria-describedby="f2621794175a4d95b035b1d08d191787-problem-title">Answers are displayed within the problem
</span>
<div class="notification-btn-wrapper">
<button type="button" class="btn btn-default btn-small notification-btn review-btn sr">Review</button>
</div>
</div>
</div>
"
data-graded="False">
<p class="loading-spinner">
<i class="fa fa-spinner fa-pulse fa-2x fa-fw"></i>
<span class="sr">Loading…</span>
</p>
</div>
</div>
</div>
</div>
</div>
<div class="xblock xblock-public_view xblock-public_view-vertical" data-runtime-class="LmsRuntime" data-usage-id="block-v1:MITx+3.15.2x+2T2017+type@vertical+block@097c2a520cb64d009930d45e688c219f" data-init="VerticalStudentView" data-runtime-version="1" data-course-id="course-v1:MITx+3.15.2x+2T2017" data-block-type="vertical" data-has-score="False" data-graded="False" data-request-token="fdee7f3e020811ef9d0216fff75c5923">
<h2 class="hd hd-2 unit-title">Liquid Crystal Displays</h2>
<div class="vert-mod">
<div class="vert vert-0" data-id="block-v1:MITx+3.15.2x+2T2017+type@html+block@1b39234e17c740ea9fd988e9a87d34ed">
<div class="xblock xblock-public_view xblock-public_view-html xmodule_display xmodule_HtmlBlock" data-runtime-class="LmsRuntime" data-usage-id="block-v1:MITx+3.15.2x+2T2017+type@html+block@1b39234e17c740ea9fd988e9a87d34ed" data-init="XBlockToXModuleShim" data-runtime-version="1" data-course-id="course-v1:MITx+3.15.2x+2T2017" data-block-type="html" data-has-score="False" data-graded="False" data-request-token="fdee7f3e020811ef9d0216fff75c5923">
<script type="json/xblock-args" class="xblock-json-init-args">
{"xmodule-type": "HTMLModule"}
</script>
<h2>Liquid Crystal Displays</h2>
<ul>
<ul>
<li>Liquid crystals are rigid, polar, organic molecules with a net dipole.</li>
<li>Their permanent dipole means that liquid crystal molecules line up in response to a static electric field.</li>
<li>Liquid crystals exhibit a highly anisotropic response to optical frequencies of light.</li>
<li>LCDs use two polarizers positioned at 90 degrees to one another. Light is filtered through the first polarizer and exits through the second polarizer.</li>
<li>Between the polarizers are two electrodes and two rubbed polymer films. The liquid crystal material sits between the polymer films, and the polymer films are designed to gradually twist the alignment of the liquid crystal by 90 degrees as we move from the top film to the bottom film.</li>
<li>When no electric field is applied, the polarization of the light is rotated by 90 degrees as it passes through the liquid crystal layer. This allows the light to pass through the bottom polarization filter, rendering the LCD transparent.</li>
<li>When an electric field is applied across the electrodes, the molecules stand on end. The liquid crystal molecules no longer rotate the plane of polarization of the incident light, the light cannot pass through the bottom polarization filter, and the display is opaque.</li>
</ul>
</ul>
<p></p>
</div>
</div>
<div class="vert vert-1" data-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@b71c910fe48e498f878d7797d238578b">
<div class="xblock xblock-public_view xblock-public_view-problem xmodule_display xmodule_ProblemBlock" data-runtime-class="LmsRuntime" data-usage-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@b71c910fe48e498f878d7797d238578b" data-init="XBlockToXModuleShim" data-runtime-version="1" data-course-id="course-v1:MITx+3.15.2x+2T2017" data-block-type="problem" data-has-score="True" data-graded="False" data-request-token="fdee7f3e020811ef9d0216fff75c5923">
<script type="json/xblock-args" class="xblock-json-init-args">
{"xmodule-type": "Problem"}
</script>
<div id="problem_b71c910fe48e498f878d7797d238578b" class="problems-wrapper" role="group"
aria-labelledby="b71c910fe48e498f878d7797d238578b-problem-title"
data-problem-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@b71c910fe48e498f878d7797d238578b" data-url="/courses/course-v1:MITx+3.15.2x+2T2017/xblock/block-v1:MITx+3.15.2x+2T2017+type@problem+block@b71c910fe48e498f878d7797d238578b/handler/xmodule_handler"
data-problem-score="0"
data-problem-total-possible="1"
data-attempts-used="0"
data-content="
<h3 class="hd hd-3 problem-header" id="b71c910fe48e498f878d7797d238578b-problem-title" aria-describedby="block-v1:MITx+3.15.2x+2T2017+type@problem+block@b71c910fe48e498f878d7797d238578b-problem-progress" tabindex="-1">
Exercise 3.2A
</h3>
<div class="problem-progress" id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@b71c910fe48e498f878d7797d238578b-problem-progress"></div>
<div class="problem">
<div>
<p>Which of the following molecules are liquid crystals?</p>
<img src="/assets/courseware/v1/7568c89781230be17ab056cd7a865e14/asset-v1:MITx+3.15.2x+2T2017+type@asset+block/315LiquidCrystals.svg" alt="A) Rigid, polar organic B) Organic C) Polar organic D) Rigid, polar organic" width="500"/>
<div class="wrapper-problem-response" tabindex="-1" aria-label="Question 1" role="group"><div class="choicegroup capa_inputtype" id="inputtype_b71c910fe48e498f878d7797d238578b_2_1">
<fieldset aria-describedby="status_b71c910fe48e498f878d7797d238578b_2_1">
<div class="field">
<input type="checkbox" name="input_b71c910fe48e498f878d7797d238578b_2_1[]" id="input_b71c910fe48e498f878d7797d238578b_2_1_choice_0" class="field-input input-checkbox" value="choice_0"/><label id="b71c910fe48e498f878d7797d238578b_2_1-choice_0-label" for="input_b71c910fe48e498f878d7797d238578b_2_1_choice_0" class="response-label field-label label-inline" aria-describedby="status_b71c910fe48e498f878d7797d238578b_2_1"> Molecule A
</label>
</div>
<div class="field">
<input type="checkbox" name="input_b71c910fe48e498f878d7797d238578b_2_1[]" id="input_b71c910fe48e498f878d7797d238578b_2_1_choice_1" class="field-input input-checkbox" value="choice_1"/><label id="b71c910fe48e498f878d7797d238578b_2_1-choice_1-label" for="input_b71c910fe48e498f878d7797d238578b_2_1_choice_1" class="response-label field-label label-inline" aria-describedby="status_b71c910fe48e498f878d7797d238578b_2_1"> Molecule B
</label>
</div>
<div class="field">
<input type="checkbox" name="input_b71c910fe48e498f878d7797d238578b_2_1[]" id="input_b71c910fe48e498f878d7797d238578b_2_1_choice_2" class="field-input input-checkbox" value="choice_2"/><label id="b71c910fe48e498f878d7797d238578b_2_1-choice_2-label" for="input_b71c910fe48e498f878d7797d238578b_2_1_choice_2" class="response-label field-label label-inline" aria-describedby="status_b71c910fe48e498f878d7797d238578b_2_1"> Molecule C
</label>
</div>
<div class="field">
<input type="checkbox" name="input_b71c910fe48e498f878d7797d238578b_2_1[]" id="input_b71c910fe48e498f878d7797d238578b_2_1_choice_3" class="field-input input-checkbox" value="choice_3"/><label id="b71c910fe48e498f878d7797d238578b_2_1-choice_3-label" for="input_b71c910fe48e498f878d7797d238578b_2_1_choice_3" class="response-label field-label label-inline" aria-describedby="status_b71c910fe48e498f878d7797d238578b_2_1"> Molecule D
</label>
</div>
<span id="answer_b71c910fe48e498f878d7797d238578b_2_1"/>
</fieldset>
<div class="indicator-container">
<span class="status unanswered" id="status_b71c910fe48e498f878d7797d238578b_2_1" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
</div></div>
<div class="solution-span">
<span id="solution_b71c910fe48e498f878d7797d238578b_solution_1"/>
</div></div>
<div class="action">
<input type="hidden" name="problem_id" value="Exercise 3.2A" />
<div class="submit-attempt-container">
<button type="button" class="submit btn-brand" data-submitting="Submitting" data-value="Submit" data-should-enable-submit-button="True" aria-describedby="submission_feedback_b71c910fe48e498f878d7797d238578b" >
<span class="submit-label">Submit</span>
</button>
<div class="submission-feedback" id="submission_feedback_b71c910fe48e498f878d7797d238578b">
<span class="sr">Some problems have options such as save, reset, hints, or show answer. These options follow the Submit button.</span>
</div>
</div>
<div class="problem-action-buttons-wrapper">
</div>
</div>
<div class="notification warning notification-gentle-alert
is-hidden"
tabindex="-1">
<span class="icon fa fa-exclamation-circle" aria-hidden="true"></span>
<span class="notification-message" aria-describedby="b71c910fe48e498f878d7797d238578b-problem-title">
</span>
<div class="notification-btn-wrapper">
<button type="button" class="btn btn-default btn-small notification-btn review-btn sr">Review</button>
</div>
</div>
<div class="notification warning notification-save
is-hidden"
tabindex="-1">
<span class="icon fa fa-save" aria-hidden="true"></span>
<span class="notification-message" aria-describedby="b71c910fe48e498f878d7797d238578b-problem-title">None
</span>
<div class="notification-btn-wrapper">
<button type="button" class="btn btn-default btn-small notification-btn review-btn sr">Review</button>
</div>
</div>
<div class="notification general notification-show-answer
is-hidden"
tabindex="-1">
<span class="icon fa fa-info-circle" aria-hidden="true"></span>
<span class="notification-message" aria-describedby="b71c910fe48e498f878d7797d238578b-problem-title">Answers are displayed within the problem
</span>
<div class="notification-btn-wrapper">
<button type="button" class="btn btn-default btn-small notification-btn review-btn sr">Review</button>
</div>
</div>
</div>
"
data-graded="False">
<p class="loading-spinner">
<i class="fa fa-spinner fa-pulse fa-2x fa-fw"></i>
<span class="sr">Loading…</span>
</p>
</div>
</div>
</div>
<div class="vert vert-2" data-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@c54be6f096874a69b9e271bdbede2eb5">
<div class="xblock xblock-public_view xblock-public_view-problem xmodule_display xmodule_ProblemBlock" data-runtime-class="LmsRuntime" data-usage-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@c54be6f096874a69b9e271bdbede2eb5" data-init="XBlockToXModuleShim" data-runtime-version="1" data-course-id="course-v1:MITx+3.15.2x+2T2017" data-block-type="problem" data-has-score="True" data-graded="False" data-request-token="fdee7f3e020811ef9d0216fff75c5923">
<script type="json/xblock-args" class="xblock-json-init-args">
{"xmodule-type": "Problem"}
</script>
<div id="problem_c54be6f096874a69b9e271bdbede2eb5" class="problems-wrapper" role="group"
aria-labelledby="c54be6f096874a69b9e271bdbede2eb5-problem-title"
data-problem-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@c54be6f096874a69b9e271bdbede2eb5" data-url="/courses/course-v1:MITx+3.15.2x+2T2017/xblock/block-v1:MITx+3.15.2x+2T2017+type@problem+block@c54be6f096874a69b9e271bdbede2eb5/handler/xmodule_handler"
data-problem-score="0"
data-problem-total-possible="3"
data-attempts-used="0"
data-content="
<h3 class="hd hd-3 problem-header" id="c54be6f096874a69b9e271bdbede2eb5-problem-title" aria-describedby="block-v1:MITx+3.15.2x+2T2017+type@problem+block@c54be6f096874a69b9e271bdbede2eb5-problem-progress" tabindex="-1">
Exercise 3.2B
</h3>
<div class="problem-progress" id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@c54be6f096874a69b9e271bdbede2eb5-problem-progress"></div>
<div class="problem">
<div>
<p>Identify the following liquid crystal phases:</p>
<img src="/assets/courseware/v1/2e9848d4ebf88b11f3db8e471ed28777/asset-v1:MITx+3.15.2x+2T2017+type@asset+block/315LC_Phases.png" alt="A) Molecules are aligned in one direction, have no other order B) Molecules are aligned and in layers C) Molecules are aligned and the alignment direction rotates as we move from layer to layer" width="700"/>
<p>Liquid Crystal A</p>
<div class="wrapper-problem-response" tabindex="-1" aria-label="Question 1" role="group"><div class="choicegroup capa_inputtype" id="inputtype_c54be6f096874a69b9e271bdbede2eb5_2_1">
<fieldset aria-describedby="status_c54be6f096874a69b9e271bdbede2eb5_2_1">
<div class="field">
<input type="radio" name="input_c54be6f096874a69b9e271bdbede2eb5_2_1" id="input_c54be6f096874a69b9e271bdbede2eb5_2_1_choice_0" class="field-input input-radio" value="choice_0"/><label id="c54be6f096874a69b9e271bdbede2eb5_2_1-choice_0-label" for="input_c54be6f096874a69b9e271bdbede2eb5_2_1_choice_0" class="response-label field-label label-inline" aria-describedby="status_c54be6f096874a69b9e271bdbede2eb5_2_1"> Chlolesteric
</label>
</div>
<div class="field">
<input type="radio" name="input_c54be6f096874a69b9e271bdbede2eb5_2_1" id="input_c54be6f096874a69b9e271bdbede2eb5_2_1_choice_1" class="field-input input-radio" value="choice_1"/><label id="c54be6f096874a69b9e271bdbede2eb5_2_1-choice_1-label" for="input_c54be6f096874a69b9e271bdbede2eb5_2_1_choice_1" class="response-label field-label label-inline" aria-describedby="status_c54be6f096874a69b9e271bdbede2eb5_2_1"> Nematic
</label>
</div>
<div class="field">
<input type="radio" name="input_c54be6f096874a69b9e271bdbede2eb5_2_1" id="input_c54be6f096874a69b9e271bdbede2eb5_2_1_choice_2" class="field-input input-radio" value="choice_2"/><label id="c54be6f096874a69b9e271bdbede2eb5_2_1-choice_2-label" for="input_c54be6f096874a69b9e271bdbede2eb5_2_1_choice_2" class="response-label field-label label-inline" aria-describedby="status_c54be6f096874a69b9e271bdbede2eb5_2_1"> Smectic
</label>
</div>
<span id="answer_c54be6f096874a69b9e271bdbede2eb5_2_1"/>
</fieldset>
<div class="indicator-container">
<span class="status unanswered" id="status_c54be6f096874a69b9e271bdbede2eb5_2_1" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
</div></div>
<p>Liquid Crystal B</p>
<div class="wrapper-problem-response" tabindex="-1" aria-label="Question 2" role="group"><div class="choicegroup capa_inputtype" id="inputtype_c54be6f096874a69b9e271bdbede2eb5_3_1">
<fieldset aria-describedby="status_c54be6f096874a69b9e271bdbede2eb5_3_1">
<div class="field">
<input type="radio" name="input_c54be6f096874a69b9e271bdbede2eb5_3_1" id="input_c54be6f096874a69b9e271bdbede2eb5_3_1_choice_0" class="field-input input-radio" value="choice_0"/><label id="c54be6f096874a69b9e271bdbede2eb5_3_1-choice_0-label" for="input_c54be6f096874a69b9e271bdbede2eb5_3_1_choice_0" class="response-label field-label label-inline" aria-describedby="status_c54be6f096874a69b9e271bdbede2eb5_3_1"> Chlolesteric
</label>
</div>
<div class="field">
<input type="radio" name="input_c54be6f096874a69b9e271bdbede2eb5_3_1" id="input_c54be6f096874a69b9e271bdbede2eb5_3_1_choice_1" class="field-input input-radio" value="choice_1"/><label id="c54be6f096874a69b9e271bdbede2eb5_3_1-choice_1-label" for="input_c54be6f096874a69b9e271bdbede2eb5_3_1_choice_1" class="response-label field-label label-inline" aria-describedby="status_c54be6f096874a69b9e271bdbede2eb5_3_1"> Nematic
</label>
</div>
<div class="field">
<input type="radio" name="input_c54be6f096874a69b9e271bdbede2eb5_3_1" id="input_c54be6f096874a69b9e271bdbede2eb5_3_1_choice_2" class="field-input input-radio" value="choice_2"/><label id="c54be6f096874a69b9e271bdbede2eb5_3_1-choice_2-label" for="input_c54be6f096874a69b9e271bdbede2eb5_3_1_choice_2" class="response-label field-label label-inline" aria-describedby="status_c54be6f096874a69b9e271bdbede2eb5_3_1"> Smectic
</label>
</div>
<span id="answer_c54be6f096874a69b9e271bdbede2eb5_3_1"/>
</fieldset>
<div class="indicator-container">
<span class="status unanswered" id="status_c54be6f096874a69b9e271bdbede2eb5_3_1" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
</div></div>
<p>Liquid Crystal C</p>
<div class="wrapper-problem-response" tabindex="-1" aria-label="Question 3" role="group"><div class="choicegroup capa_inputtype" id="inputtype_c54be6f096874a69b9e271bdbede2eb5_4_1">
<fieldset aria-describedby="status_c54be6f096874a69b9e271bdbede2eb5_4_1">
<div class="field">
<input type="radio" name="input_c54be6f096874a69b9e271bdbede2eb5_4_1" id="input_c54be6f096874a69b9e271bdbede2eb5_4_1_choice_0" class="field-input input-radio" value="choice_0"/><label id="c54be6f096874a69b9e271bdbede2eb5_4_1-choice_0-label" for="input_c54be6f096874a69b9e271bdbede2eb5_4_1_choice_0" class="response-label field-label label-inline" aria-describedby="status_c54be6f096874a69b9e271bdbede2eb5_4_1"> Chlolesteric
</label>
</div>
<div class="field">
<input type="radio" name="input_c54be6f096874a69b9e271bdbede2eb5_4_1" id="input_c54be6f096874a69b9e271bdbede2eb5_4_1_choice_1" class="field-input input-radio" value="choice_1"/><label id="c54be6f096874a69b9e271bdbede2eb5_4_1-choice_1-label" for="input_c54be6f096874a69b9e271bdbede2eb5_4_1_choice_1" class="response-label field-label label-inline" aria-describedby="status_c54be6f096874a69b9e271bdbede2eb5_4_1"> Nematic
</label>
</div>
<div class="field">
<input type="radio" name="input_c54be6f096874a69b9e271bdbede2eb5_4_1" id="input_c54be6f096874a69b9e271bdbede2eb5_4_1_choice_2" class="field-input input-radio" value="choice_2"/><label id="c54be6f096874a69b9e271bdbede2eb5_4_1-choice_2-label" for="input_c54be6f096874a69b9e271bdbede2eb5_4_1_choice_2" class="response-label field-label label-inline" aria-describedby="status_c54be6f096874a69b9e271bdbede2eb5_4_1"> Smectic
</label>
</div>
<span id="answer_c54be6f096874a69b9e271bdbede2eb5_4_1"/>
</fieldset>
<div class="indicator-container">
<span class="status unanswered" id="status_c54be6f096874a69b9e271bdbede2eb5_4_1" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
</div></div>
</div>
<div class="action">
<input type="hidden" name="problem_id" value="Exercise 3.2B" />
<div class="submit-attempt-container">
<button type="button" class="submit btn-brand" data-submitting="Submitting" data-value="Submit" data-should-enable-submit-button="True" aria-describedby="submission_feedback_c54be6f096874a69b9e271bdbede2eb5" >
<span class="submit-label">Submit</span>
</button>
<div class="submission-feedback" id="submission_feedback_c54be6f096874a69b9e271bdbede2eb5">
<span class="sr">Some problems have options such as save, reset, hints, or show answer. These options follow the Submit button.</span>
</div>
</div>
<div class="problem-action-buttons-wrapper">
</div>
</div>
<div class="notification warning notification-gentle-alert
is-hidden"
tabindex="-1">
<span class="icon fa fa-exclamation-circle" aria-hidden="true"></span>
<span class="notification-message" aria-describedby="c54be6f096874a69b9e271bdbede2eb5-problem-title">
</span>
<div class="notification-btn-wrapper">
<button type="button" class="btn btn-default btn-small notification-btn review-btn sr">Review</button>
</div>
</div>
<div class="notification warning notification-save
is-hidden"
tabindex="-1">
<span class="icon fa fa-save" aria-hidden="true"></span>
<span class="notification-message" aria-describedby="c54be6f096874a69b9e271bdbede2eb5-problem-title">None
</span>
<div class="notification-btn-wrapper">
<button type="button" class="btn btn-default btn-small notification-btn review-btn sr">Review</button>
</div>
</div>
<div class="notification general notification-show-answer
is-hidden"
tabindex="-1">
<span class="icon fa fa-info-circle" aria-hidden="true"></span>
<span class="notification-message" aria-describedby="c54be6f096874a69b9e271bdbede2eb5-problem-title">Answers are displayed within the problem
</span>
<div class="notification-btn-wrapper">
<button type="button" class="btn btn-default btn-small notification-btn review-btn sr">Review</button>
</div>
</div>
</div>
"
data-graded="False">
<p class="loading-spinner">
<i class="fa fa-spinner fa-pulse fa-2x fa-fw"></i>
<span class="sr">Loading…</span>
</p>
</div>
</div>
</div>
</div>
</div>
<div class="xblock xblock-public_view xblock-public_view-vertical" data-runtime-class="LmsRuntime" data-usage-id="block-v1:MITx+3.15.2x+2T2017+type@vertical+block@3feae649bbd2471ca1d3572812269f0b" data-init="VerticalStudentView" data-runtime-version="1" data-course-id="course-v1:MITx+3.15.2x+2T2017" data-block-type="vertical" data-has-score="False" data-graded="False" data-request-token="fdee7f3e020811ef9d0216fff75c5923">
<h2 class="hd hd-2 unit-title">Attenuation</h2>
<div class="vert-mod">
<div class="vert vert-0" data-id="block-v1:MITx+3.15.2x+2T2017+type@html+block@10df8597bc7b44f89ced3372919b2f4c">
<div class="xblock xblock-public_view xblock-public_view-html xmodule_display xmodule_HtmlBlock" data-runtime-class="LmsRuntime" data-usage-id="block-v1:MITx+3.15.2x+2T2017+type@html+block@10df8597bc7b44f89ced3372919b2f4c" data-init="XBlockToXModuleShim" data-runtime-version="1" data-course-id="course-v1:MITx+3.15.2x+2T2017" data-block-type="html" data-has-score="False" data-graded="False" data-request-token="fdee7f3e020811ef9d0216fff75c5923">
<script type="json/xblock-args" class="xblock-json-init-args">
{"xmodule-type": "HTMLModule"}
</script>
<h2>Attenuation</h2>
<ul>
<ul>
<li>Attenuation is the amount of power that is lost as a signal travels down a fiber. We measure attenuation (\(\alpha\)) in decibels per unit length.</li>
<ul>
<ul>
<ul>
<li>\(\alpha = \frac{10}{L}log_{10}(P_{in}/P_{out})\)</li>
</ul>
</ul>
</ul>
<li>Both absorption and scattering cause power to be lost as light travels down a waveguide.</li>
<li>The attenuation minimum for silica occurs around \(1.55 \mu m\).</li>
</ul>
</ul>
<p><img src="/assets/courseware/v1/10d7e67aa7bcfa567443aa78615e3d96/asset-v1:MITx+3.15.2x+2T2017+type@asset+block/315SilicaAttenuation.jpg" alt="Attenuation in silica. Attenuation minimum occurs around 1.55 micons" type="saveimage" target="[object Object]" width="700" height="372" /></p>
<p></p>
</div>
</div>
<div class="vert vert-1" data-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@54fa83771d9e4841931d500d022cf749">
<div class="xblock xblock-public_view xblock-public_view-problem xmodule_display xmodule_ProblemBlock" data-runtime-class="LmsRuntime" data-usage-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@54fa83771d9e4841931d500d022cf749" data-init="XBlockToXModuleShim" data-runtime-version="1" data-course-id="course-v1:MITx+3.15.2x+2T2017" data-block-type="problem" data-has-score="True" data-graded="False" data-request-token="fdee7f3e020811ef9d0216fff75c5923">
<script type="json/xblock-args" class="xblock-json-init-args">
{"xmodule-type": "Problem"}
</script>
<div id="problem_54fa83771d9e4841931d500d022cf749" class="problems-wrapper" role="group"
aria-labelledby="54fa83771d9e4841931d500d022cf749-problem-title"
data-problem-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@54fa83771d9e4841931d500d022cf749" data-url="/courses/course-v1:MITx+3.15.2x+2T2017/xblock/block-v1:MITx+3.15.2x+2T2017+type@problem+block@54fa83771d9e4841931d500d022cf749/handler/xmodule_handler"
data-problem-score="0"
data-problem-total-possible="1"
data-attempts-used="0"
data-content="
<h3 class="hd hd-3 problem-header" id="54fa83771d9e4841931d500d022cf749-problem-title" aria-describedby="block-v1:MITx+3.15.2x+2T2017+type@problem+block@54fa83771d9e4841931d500d022cf749-problem-progress" tabindex="-1">
Exercise 3.3A
</h3>
<div class="problem-progress" id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@54fa83771d9e4841931d500d022cf749-problem-progress"></div>
<div class="problem">
<div>
<p>The attenuation of \(1.2 \mu m\) light in silica is approximately \(0.5 dB/km\). What percentage of the original signal will remain after the light has traveled down a \(10 \; km\) fiber?</p>
<div class="wrapper-problem-response" tabindex="-1" aria-label="Question 1" role="group"><div id="formulaequationinput_54fa83771d9e4841931d500d022cf749_2_1" class="inputtype formulaequationinput">
<div class="unanswered">
<input type="text" name="input_54fa83771d9e4841931d500d022cf749_2_1" id="input_54fa83771d9e4841931d500d022cf749_2_1" data-input-id="54fa83771d9e4841931d500d022cf749_2_1" value="" aria-describedby="status_54fa83771d9e4841931d500d022cf749_2_1" size="20"/>
<span class="trailing_text" id="trailing_text_54fa83771d9e4841931d500d022cf749_2_1"/>
<span class="status unanswered" id="status_54fa83771d9e4841931d500d022cf749_2_1" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
<p id="answer_54fa83771d9e4841931d500d022cf749_2_1" class="answer"/>
<div id="input_54fa83771d9e4841931d500d022cf749_2_1_preview" class="equation">
\(\)
<img src="/static/images/spinner.bc34f953403f.gif" class="loading" alt="Loading"/>
</div>
</div>
<div class="script_placeholder" data-src="/static/js/capa/src/formula_equation_preview.b1967ab28c31.js"/>
</div></div>
<div class="solution-span">
<span id="solution_54fa83771d9e4841931d500d022cf749_solution_1"/>
</div></div>
<div class="action">
<input type="hidden" name="problem_id" value="Exercise 3.3A" />
<div class="submit-attempt-container">
<button type="button" class="submit btn-brand" data-submitting="Submitting" data-value="Submit" data-should-enable-submit-button="True" aria-describedby="submission_feedback_54fa83771d9e4841931d500d022cf749" >
<span class="submit-label">Submit</span>
</button>
<div class="submission-feedback" id="submission_feedback_54fa83771d9e4841931d500d022cf749">
<span class="sr">Some problems have options such as save, reset, hints, or show answer. These options follow the Submit button.</span>
</div>
</div>
<div class="problem-action-buttons-wrapper">
</div>
</div>
<div class="notification warning notification-gentle-alert
is-hidden"
tabindex="-1">
<span class="icon fa fa-exclamation-circle" aria-hidden="true"></span>
<span class="notification-message" aria-describedby="54fa83771d9e4841931d500d022cf749-problem-title">
</span>
<div class="notification-btn-wrapper">
<button type="button" class="btn btn-default btn-small notification-btn review-btn sr">Review</button>
</div>
</div>
<div class="notification warning notification-save
is-hidden"
tabindex="-1">
<span class="icon fa fa-save" aria-hidden="true"></span>
<span class="notification-message" aria-describedby="54fa83771d9e4841931d500d022cf749-problem-title">None
</span>
<div class="notification-btn-wrapper">
<button type="button" class="btn btn-default btn-small notification-btn review-btn sr">Review</button>
</div>
</div>
<div class="notification general notification-show-answer
is-hidden"
tabindex="-1">
<span class="icon fa fa-info-circle" aria-hidden="true"></span>
<span class="notification-message" aria-describedby="54fa83771d9e4841931d500d022cf749-problem-title">Answers are displayed within the problem
</span>
<div class="notification-btn-wrapper">
<button type="button" class="btn btn-default btn-small notification-btn review-btn sr">Review</button>
</div>
</div>
</div>
"
data-graded="False">
<p class="loading-spinner">
<i class="fa fa-spinner fa-pulse fa-2x fa-fw"></i>
<span class="sr">Loading…</span>
</p>
</div>
</div>
</div>
<div class="vert vert-2" data-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@6c82df865f0243308bdc4c36645536ee">
<div class="xblock xblock-public_view xblock-public_view-problem xmodule_display xmodule_ProblemBlock" data-runtime-class="LmsRuntime" data-usage-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@6c82df865f0243308bdc4c36645536ee" data-init="XBlockToXModuleShim" data-runtime-version="1" data-course-id="course-v1:MITx+3.15.2x+2T2017" data-block-type="problem" data-has-score="True" data-graded="False" data-request-token="fdee7f3e020811ef9d0216fff75c5923">
<script type="json/xblock-args" class="xblock-json-init-args">
{"xmodule-type": "Problem"}
</script>
<div id="problem_6c82df865f0243308bdc4c36645536ee" class="problems-wrapper" role="group"
aria-labelledby="6c82df865f0243308bdc4c36645536ee-problem-title"
data-problem-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@6c82df865f0243308bdc4c36645536ee" data-url="/courses/course-v1:MITx+3.15.2x+2T2017/xblock/block-v1:MITx+3.15.2x+2T2017+type@problem+block@6c82df865f0243308bdc4c36645536ee/handler/xmodule_handler"
data-problem-score="0"
data-problem-total-possible="1"
data-attempts-used="0"
data-content="
<h3 class="hd hd-3 problem-header" id="6c82df865f0243308bdc4c36645536ee-problem-title" aria-describedby="block-v1:MITx+3.15.2x+2T2017+type@problem+block@6c82df865f0243308bdc4c36645536ee-problem-progress" tabindex="-1">
Exercise 3.3B
</h3>
<div class="problem-progress" id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@6c82df865f0243308bdc4c36645536ee-problem-progress"></div>
<div class="problem">
<div>
<p>How long can we make our fiber if we need \(5\%\) of the original signal to remain at the end?</p>
<p>\(L\) (in \(km\)):</p>
<div class="wrapper-problem-response" tabindex="-1" aria-label="Question 1" role="group"><div id="formulaequationinput_6c82df865f0243308bdc4c36645536ee_2_1" class="inputtype formulaequationinput">
<div class="unanswered">
<input type="text" name="input_6c82df865f0243308bdc4c36645536ee_2_1" id="input_6c82df865f0243308bdc4c36645536ee_2_1" data-input-id="6c82df865f0243308bdc4c36645536ee_2_1" value="" aria-describedby="status_6c82df865f0243308bdc4c36645536ee_2_1" size="20"/>
<span class="trailing_text" id="trailing_text_6c82df865f0243308bdc4c36645536ee_2_1"/>
<span class="status unanswered" id="status_6c82df865f0243308bdc4c36645536ee_2_1" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
<p id="answer_6c82df865f0243308bdc4c36645536ee_2_1" class="answer"/>
<div id="input_6c82df865f0243308bdc4c36645536ee_2_1_preview" class="equation">
\(\)
<img src="/static/images/spinner.bc34f953403f.gif" class="loading" alt="Loading"/>
</div>
</div>
<div class="script_placeholder" data-src="/static/js/capa/src/formula_equation_preview.b1967ab28c31.js"/>
</div></div>
<div class="solution-span">
<span id="solution_6c82df865f0243308bdc4c36645536ee_solution_1"/>
</div></div>
<div class="action">
<input type="hidden" name="problem_id" value="Exercise 3.3B" />
<div class="submit-attempt-container">
<button type="button" class="submit btn-brand" data-submitting="Submitting" data-value="Submit" data-should-enable-submit-button="True" aria-describedby="submission_feedback_6c82df865f0243308bdc4c36645536ee" >
<span class="submit-label">Submit</span>
</button>
<div class="submission-feedback" id="submission_feedback_6c82df865f0243308bdc4c36645536ee">
<span class="sr">Some problems have options such as save, reset, hints, or show answer. These options follow the Submit button.</span>
</div>
</div>
<div class="problem-action-buttons-wrapper">
</div>
</div>
<div class="notification warning notification-gentle-alert
is-hidden"
tabindex="-1">
<span class="icon fa fa-exclamation-circle" aria-hidden="true"></span>
<span class="notification-message" aria-describedby="6c82df865f0243308bdc4c36645536ee-problem-title">
</span>
<div class="notification-btn-wrapper">
<button type="button" class="btn btn-default btn-small notification-btn review-btn sr">Review</button>
</div>
</div>
<div class="notification warning notification-save
is-hidden"
tabindex="-1">
<span class="icon fa fa-save" aria-hidden="true"></span>
<span class="notification-message" aria-describedby="6c82df865f0243308bdc4c36645536ee-problem-title">None
</span>
<div class="notification-btn-wrapper">
<button type="button" class="btn btn-default btn-small notification-btn review-btn sr">Review</button>
</div>
</div>
<div class="notification general notification-show-answer
is-hidden"
tabindex="-1">
<span class="icon fa fa-info-circle" aria-hidden="true"></span>
<span class="notification-message" aria-describedby="6c82df865f0243308bdc4c36645536ee-problem-title">Answers are displayed within the problem
</span>
<div class="notification-btn-wrapper">
<button type="button" class="btn btn-default btn-small notification-btn review-btn sr">Review</button>
</div>
</div>
</div>
"
data-graded="False">
<p class="loading-spinner">
<i class="fa fa-spinner fa-pulse fa-2x fa-fw"></i>
<span class="sr">Loading…</span>
</p>
</div>
</div>
</div>
</div>
</div>
<div class="xblock xblock-public_view xblock-public_view-vertical" data-runtime-class="LmsRuntime" data-usage-id="block-v1:MITx+3.15.2x+2T2017+type@vertical+block@551492c4787141df91704ff1bbc7d441" data-init="VerticalStudentView" data-runtime-version="1" data-course-id="course-v1:MITx+3.15.2x+2T2017" data-block-type="vertical" data-has-score="False" data-graded="False" data-request-token="fdee7f3e020811ef9d0216fff75c5923">
<h2 class="hd hd-2 unit-title">Dispersion</h2>
<div class="vert-mod">
<div class="vert vert-0" data-id="block-v1:MITx+3.15.2x+2T2017+type@html+block@6c5dd8a8193f43ba9b8bf696659ef9ef">
<div class="xblock xblock-public_view xblock-public_view-html xmodule_display xmodule_HtmlBlock" data-runtime-class="LmsRuntime" data-usage-id="block-v1:MITx+3.15.2x+2T2017+type@html+block@6c5dd8a8193f43ba9b8bf696659ef9ef" data-init="XBlockToXModuleShim" data-runtime-version="1" data-course-id="course-v1:MITx+3.15.2x+2T2017" data-block-type="html" data-has-score="False" data-graded="False" data-request-token="fdee7f3e020811ef9d0216fff75c5923">
<script type="json/xblock-args" class="xblock-json-init-args">
{"xmodule-type": "HTMLModule"}
</script>
<h2>Dispersion</h2>
<ul>
<ul>
<li>Dispersion describes the spreading of a light pulse as light moves down the waveguide.</li>
<li>There are several different sources of dispersion.</li>
<li>Modal dispersion occurs because the different modes in a fiber have different group velocities. This means that different modes travel down the fiber at different speeds.</li>
<ul>
<ul>
<ul>
<li>Modal dispersion can be corrected by using either a graded index or a single mode fiber.</li>
</ul>
</ul>
</ul>
<li>Materials dispersion occurs because the refractive index of a material depends on the wavelength of the light. This means that different colors of light travel down a waveguide at different speeds.</li>
<ul>
<ul>
<ul>
<li>We minimize materials dispersion by selecting an operating wavelength with a low dispersion coefficient.</li>
<li>The pulse width (usually in \(ps\) or \(ns\)) after a pulse of light has traveled a distance \(L\) down a fiber is given as \(|D_{\lambda}|\sigma_{\lambda}L\), where \(D_{\lambda}\) is the dispersion coefficient, and \(\sigma_{\lambda}\) is the spectral width of the incident light.</li>
<li>In silica, materials dispersion is lowest around \(1.3\) microns.</li>
</ul>
</ul>
</ul>
<li>Waveguide dispersion occurs because the shape of modes within a waveguide is different for different colors of light. This means that different wavelengths sample different refractive indices within the optical fiber.</li>
<ul>
<ul>
<ul>
<li>Waveguide dispersion can be combined with modal dispersion such that they cancel each other out, giving us zero net dispersion.</li>
</ul>
</ul>
</ul>
</ul>
</ul>
<p></p>
</div>
</div>
<div class="vert vert-1" data-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@49e451b75abb4ac78e1f0ed580f442d6">
<div class="xblock xblock-public_view xblock-public_view-problem xmodule_display xmodule_ProblemBlock" data-runtime-class="LmsRuntime" data-usage-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@49e451b75abb4ac78e1f0ed580f442d6" data-init="XBlockToXModuleShim" data-runtime-version="1" data-course-id="course-v1:MITx+3.15.2x+2T2017" data-block-type="problem" data-has-score="True" data-graded="False" data-request-token="fdee7f3e020811ef9d0216fff75c5923">
<script type="json/xblock-args" class="xblock-json-init-args">
{"xmodule-type": "Problem"}
</script>
<div id="problem_49e451b75abb4ac78e1f0ed580f442d6" class="problems-wrapper" role="group"
aria-labelledby="49e451b75abb4ac78e1f0ed580f442d6-problem-title"
data-problem-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@49e451b75abb4ac78e1f0ed580f442d6" data-url="/courses/course-v1:MITx+3.15.2x+2T2017/xblock/block-v1:MITx+3.15.2x+2T2017+type@problem+block@49e451b75abb4ac78e1f0ed580f442d6/handler/xmodule_handler"
data-problem-score="0"
data-problem-total-possible="1"
data-attempts-used="0"
data-content="
<h3 class="hd hd-3 problem-header" id="49e451b75abb4ac78e1f0ed580f442d6-problem-title" aria-describedby="block-v1:MITx+3.15.2x+2T2017+type@problem+block@49e451b75abb4ac78e1f0ed580f442d6-problem-progress" tabindex="-1">
Exercise 3.4A
</h3>
<div class="problem-progress" id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@49e451b75abb4ac78e1f0ed580f442d6-problem-progress"></div>
<div class="problem">
<div>
<p>The dispersion coefficient of \(1.4\; \mu m\) light is approximately \(10 \; ps/km \cdot nm\) in silica. If we employ a \(1.4 \; \mu m\) light source with a spectral width of \(40 \; nm\), what is the pulse width after the light has travelled down a \(50 \; km\) fiber?</p>
<p>Pulse width (in \(ns\)):</p>
<div class="wrapper-problem-response" tabindex="-1" aria-label="Question 1" role="group"><div id="formulaequationinput_49e451b75abb4ac78e1f0ed580f442d6_2_1" class="inputtype formulaequationinput">
<div class="unanswered">
<input type="text" name="input_49e451b75abb4ac78e1f0ed580f442d6_2_1" id="input_49e451b75abb4ac78e1f0ed580f442d6_2_1" data-input-id="49e451b75abb4ac78e1f0ed580f442d6_2_1" value="" aria-describedby="status_49e451b75abb4ac78e1f0ed580f442d6_2_1" size="20"/>
<span class="trailing_text" id="trailing_text_49e451b75abb4ac78e1f0ed580f442d6_2_1"/>
<span class="status unanswered" id="status_49e451b75abb4ac78e1f0ed580f442d6_2_1" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
<p id="answer_49e451b75abb4ac78e1f0ed580f442d6_2_1" class="answer"/>
<div id="input_49e451b75abb4ac78e1f0ed580f442d6_2_1_preview" class="equation">
\(\)
<img src="/static/images/spinner.bc34f953403f.gif" class="loading" alt="Loading"/>
</div>
</div>
<div class="script_placeholder" data-src="/static/js/capa/src/formula_equation_preview.b1967ab28c31.js"/>
</div></div>
<div class="solution-span">
<span id="solution_49e451b75abb4ac78e1f0ed580f442d6_solution_1"/>
</div></div>
<div class="action">
<input type="hidden" name="problem_id" value="Exercise 3.4A" />
<div class="submit-attempt-container">
<button type="button" class="submit btn-brand" data-submitting="Submitting" data-value="Submit" data-should-enable-submit-button="True" aria-describedby="submission_feedback_49e451b75abb4ac78e1f0ed580f442d6" >
<span class="submit-label">Submit</span>
</button>
<div class="submission-feedback" id="submission_feedback_49e451b75abb4ac78e1f0ed580f442d6">
<span class="sr">Some problems have options such as save, reset, hints, or show answer. These options follow the Submit button.</span>
</div>
</div>
<div class="problem-action-buttons-wrapper">
</div>
</div>
<div class="notification warning notification-gentle-alert
is-hidden"
tabindex="-1">
<span class="icon fa fa-exclamation-circle" aria-hidden="true"></span>
<span class="notification-message" aria-describedby="49e451b75abb4ac78e1f0ed580f442d6-problem-title">
</span>
<div class="notification-btn-wrapper">
<button type="button" class="btn btn-default btn-small notification-btn review-btn sr">Review</button>
</div>
</div>
<div class="notification warning notification-save
is-hidden"
tabindex="-1">
<span class="icon fa fa-save" aria-hidden="true"></span>
<span class="notification-message" aria-describedby="49e451b75abb4ac78e1f0ed580f442d6-problem-title">None
</span>
<div class="notification-btn-wrapper">
<button type="button" class="btn btn-default btn-small notification-btn review-btn sr">Review</button>
</div>
</div>
<div class="notification general notification-show-answer
is-hidden"
tabindex="-1">
<span class="icon fa fa-info-circle" aria-hidden="true"></span>
<span class="notification-message" aria-describedby="49e451b75abb4ac78e1f0ed580f442d6-problem-title">Answers are displayed within the problem
</span>
<div class="notification-btn-wrapper">
<button type="button" class="btn btn-default btn-small notification-btn review-btn sr">Review</button>
</div>
</div>
</div>
"
data-graded="False">
<p class="loading-spinner">
<i class="fa fa-spinner fa-pulse fa-2x fa-fw"></i>
<span class="sr">Loading…</span>
</p>
</div>
</div>
</div>
<div class="vert vert-2" data-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@737578c327b14167944877e137eb3dd2">
<div class="xblock xblock-public_view xblock-public_view-problem xmodule_display xmodule_ProblemBlock" data-runtime-class="LmsRuntime" data-usage-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@737578c327b14167944877e137eb3dd2" data-init="XBlockToXModuleShim" data-runtime-version="1" data-course-id="course-v1:MITx+3.15.2x+2T2017" data-block-type="problem" data-has-score="True" data-graded="False" data-request-token="fdee7f3e020811ef9d0216fff75c5923">
<script type="json/xblock-args" class="xblock-json-init-args">
{"xmodule-type": "Problem"}
</script>
<div id="problem_737578c327b14167944877e137eb3dd2" class="problems-wrapper" role="group"
aria-labelledby="737578c327b14167944877e137eb3dd2-problem-title"
data-problem-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@737578c327b14167944877e137eb3dd2" data-url="/courses/course-v1:MITx+3.15.2x+2T2017/xblock/block-v1:MITx+3.15.2x+2T2017+type@problem+block@737578c327b14167944877e137eb3dd2/handler/xmodule_handler"
data-problem-score="0"
data-problem-total-possible="1"
data-attempts-used="0"
data-content="
<h3 class="hd hd-3 problem-header" id="737578c327b14167944877e137eb3dd2-problem-title" aria-describedby="block-v1:MITx+3.15.2x+2T2017+type@problem+block@737578c327b14167944877e137eb3dd2-problem-progress" tabindex="-1">
Exercise 3.4B
</h3>
<div class="problem-progress" id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@737578c327b14167944877e137eb3dd2-problem-progress"></div>
<div class="problem">
<div>
<p>Estimate the maximum data rate that could be transmitted given the conditions described in Part A.</p>
<p>Maximum Data Rate (\(MHz\)):</p>
<div class="wrapper-problem-response" tabindex="-1" aria-label="Question 1" role="group"><div id="formulaequationinput_737578c327b14167944877e137eb3dd2_2_1" class="inputtype formulaequationinput">
<div class="unanswered">
<input type="text" name="input_737578c327b14167944877e137eb3dd2_2_1" id="input_737578c327b14167944877e137eb3dd2_2_1" data-input-id="737578c327b14167944877e137eb3dd2_2_1" value="" aria-describedby="status_737578c327b14167944877e137eb3dd2_2_1" size="20"/>
<span class="trailing_text" id="trailing_text_737578c327b14167944877e137eb3dd2_2_1"/>
<span class="status unanswered" id="status_737578c327b14167944877e137eb3dd2_2_1" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
<p id="answer_737578c327b14167944877e137eb3dd2_2_1" class="answer"/>
<div id="input_737578c327b14167944877e137eb3dd2_2_1_preview" class="equation">
\(\)
<img src="/static/images/spinner.bc34f953403f.gif" class="loading" alt="Loading"/>
</div>
</div>
<div class="script_placeholder" data-src="/static/js/capa/src/formula_equation_preview.b1967ab28c31.js"/>
</div></div>
<div class="solution-span">
<span id="solution_737578c327b14167944877e137eb3dd2_solution_1"/>
</div></div>
<div class="action">
<input type="hidden" name="problem_id" value="Exercise 3.4B" />
<div class="submit-attempt-container">
<button type="button" class="submit btn-brand" data-submitting="Submitting" data-value="Submit" data-should-enable-submit-button="True" aria-describedby="submission_feedback_737578c327b14167944877e137eb3dd2" >
<span class="submit-label">Submit</span>
</button>
<div class="submission-feedback" id="submission_feedback_737578c327b14167944877e137eb3dd2">
<span class="sr">Some problems have options such as save, reset, hints, or show answer. These options follow the Submit button.</span>
</div>
</div>
<div class="problem-action-buttons-wrapper">
</div>
</div>
<div class="notification warning notification-gentle-alert
is-hidden"
tabindex="-1">
<span class="icon fa fa-exclamation-circle" aria-hidden="true"></span>
<span class="notification-message" aria-describedby="737578c327b14167944877e137eb3dd2-problem-title">
</span>
<div class="notification-btn-wrapper">
<button type="button" class="btn btn-default btn-small notification-btn review-btn sr">Review</button>
</div>
</div>
<div class="notification warning notification-save
is-hidden"
tabindex="-1">
<span class="icon fa fa-save" aria-hidden="true"></span>
<span class="notification-message" aria-describedby="737578c327b14167944877e137eb3dd2-problem-title">None
</span>
<div class="notification-btn-wrapper">
<button type="button" class="btn btn-default btn-small notification-btn review-btn sr">Review</button>
</div>
</div>
<div class="notification general notification-show-answer
is-hidden"
tabindex="-1">
<span class="icon fa fa-info-circle" aria-hidden="true"></span>
<span class="notification-message" aria-describedby="737578c327b14167944877e137eb3dd2-problem-title">Answers are displayed within the problem
</span>
<div class="notification-btn-wrapper">
<button type="button" class="btn btn-default btn-small notification-btn review-btn sr">Review</button>
</div>
</div>
</div>
"
data-graded="False">
<p class="loading-spinner">
<i class="fa fa-spinner fa-pulse fa-2x fa-fw"></i>
<span class="sr">Loading…</span>
</p>
</div>
</div>
</div>
</div>
</div>
© All Rights Reserved