<div class="xblock xblock-public_view xblock-public_view-vertical" data-course-id="course-v1:MITx+3.15.2x+2T2017" data-runtime-class="LmsRuntime" data-init="VerticalStudentView" data-usage-id="block-v1:MITx+3.15.2x+2T2017+type@vertical+block@16e9ebc4e628455981967d5e89ee8c37" data-has-score="False" data-runtime-version="1" data-block-type="vertical" data-request-token="0c3f6f54ed5411eeb4401299a322540b" data-graded="True">
<h2 class="hd hd-2 unit-title">Problem 4.1</h2>
<div class="vert-mod">
<div class="vert vert-0" data-id="block-v1:MITx+3.15.2x+2T2017+type@html+block@2498c2cd60b2476c818a069edefa7940">
<div class="xblock xblock-public_view xblock-public_view-html xmodule_display xmodule_HtmlBlock" data-course-id="course-v1:MITx+3.15.2x+2T2017" data-runtime-class="LmsRuntime" data-init="XBlockToXModuleShim" data-usage-id="block-v1:MITx+3.15.2x+2T2017+type@html+block@2498c2cd60b2476c818a069edefa7940" data-has-score="False" data-runtime-version="1" data-block-type="html" data-request-token="0c3f6f54ed5411eeb4401299a322540b" data-graded="True">
<script type="json/xblock-args" class="xblock-json-init-args">
{"xmodule-type": "HTMLModule"}
</script>
<h2>problem 4.1</h2>
<p>A friend has proposed a design for an electrooptical display which has the following structure:</p>
<p><img src="/assets/courseware/v1/0668faf92a7d91f3810ba8dd145c5467/asset-v1:MITx+3.15.2x+2T2017+type@asset+block/315PS8Ex1_1.jpg" width="600" height="230" type="saveimage" target="[object Object]" /></p>
<p></p>
<p>"Incident light can be reflected from both the top and bottom surfaces of the electrooptical film. When the two reflected beams are in phase, the display appears reflective (bright). When they are out of phase, the light is not reflected so the display appears dark."</p>
<p></p>
<p>To test this idea, you chose an electrooptical material with a thickness of \(1 \mu m\), a refractive index of \(n=2\), and a Pockels coefficient of \(10^{-9} m/V\) for yellow light (\(500 nm\) wavelength). </p>
<p></p>
<p>A plot of reflectivity vs. voltage for this device is shown below:</p>
<p><img width="400" src="/assets/courseware/v1/f61b3ad08fc675473ec5147097111e5c/asset-v1:MITx+3.15.2x+2T2017+type@asset+block/315PS8Ex1_2.jpg" /></p>
<p></p>
</div>
</div>
<div class="vert vert-1" data-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@2fc2221016ca4bbbb4485f0d175996b3">
<div class="xblock xblock-public_view xblock-public_view-problem xmodule_display xmodule_ProblemBlock" data-course-id="course-v1:MITx+3.15.2x+2T2017" data-runtime-class="LmsRuntime" data-init="XBlockToXModuleShim" data-usage-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@2fc2221016ca4bbbb4485f0d175996b3" data-has-score="True" data-runtime-version="1" data-block-type="problem" data-request-token="0c3f6f54ed5411eeb4401299a322540b" data-graded="True">
<script type="json/xblock-args" class="xblock-json-init-args">
{"xmodule-type": "Problem"}
</script>
<div id="problem_2fc2221016ca4bbbb4485f0d175996b3" class="problems-wrapper" role="group"
aria-labelledby="2fc2221016ca4bbbb4485f0d175996b3-problem-title"
data-problem-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@2fc2221016ca4bbbb4485f0d175996b3" data-url="/courses/course-v1:MITx+3.15.2x+2T2017/xblock/block-v1:MITx+3.15.2x+2T2017+type@problem+block@2fc2221016ca4bbbb4485f0d175996b3/handler/xmodule_handler"
data-problem-score="0"
data-problem-total-possible="2"
data-attempts-used="0"
data-content="
<h3 class="hd hd-3 problem-header" id="2fc2221016ca4bbbb4485f0d175996b3-problem-title" aria-describedby="block-v1:MITx+3.15.2x+2T2017+type@problem+block@2fc2221016ca4bbbb4485f0d175996b3-problem-progress" tabindex="-1">
problem
</h3>
<div class="problem-progress" id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@2fc2221016ca4bbbb4485f0d175996b3-problem-progress"></div>
<div class="problem">
<div>
<p>Assume that a change in refractive index of \(\Delta n = 0.125\) is required to switch the display from reflective to dark when the light comes in normal to the film plane.</p>
<p> What electric field \(E\) must be applied to switch the display from reflective to dark?</p>
<p>\(E\) (in V/m):</p>
<div class="wrapper-problem-response" tabindex="-1" aria-label="Question 1" role="group"><div id="formulaequationinput_2fc2221016ca4bbbb4485f0d175996b3_2_1" class="inputtype formulaequationinput">
<div class="unanswered">
<input type="text" name="input_2fc2221016ca4bbbb4485f0d175996b3_2_1" id="input_2fc2221016ca4bbbb4485f0d175996b3_2_1" data-input-id="2fc2221016ca4bbbb4485f0d175996b3_2_1" value="" aria-describedby="status_2fc2221016ca4bbbb4485f0d175996b3_2_1" size="20"/>
<span class="trailing_text" id="trailing_text_2fc2221016ca4bbbb4485f0d175996b3_2_1"/>
<span class="status unanswered" id="status_2fc2221016ca4bbbb4485f0d175996b3_2_1" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
<p id="answer_2fc2221016ca4bbbb4485f0d175996b3_2_1" class="answer"/>
<div id="input_2fc2221016ca4bbbb4485f0d175996b3_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>
<p>Therefore, what voltage \(V\) must we apply across the film to switch the display from reflective to dark? </p>
<p>\(V\) (in volts):</p>
<div class="wrapper-problem-response" tabindex="-1" aria-label="Question 2" role="group"><div id="formulaequationinput_2fc2221016ca4bbbb4485f0d175996b3_3_1" class="inputtype formulaequationinput">
<div class="unanswered">
<input type="text" name="input_2fc2221016ca4bbbb4485f0d175996b3_3_1" id="input_2fc2221016ca4bbbb4485f0d175996b3_3_1" data-input-id="2fc2221016ca4bbbb4485f0d175996b3_3_1" value="" aria-describedby="status_2fc2221016ca4bbbb4485f0d175996b3_3_1" size="20"/>
<span class="trailing_text" id="trailing_text_2fc2221016ca4bbbb4485f0d175996b3_3_1"/>
<span class="status unanswered" id="status_2fc2221016ca4bbbb4485f0d175996b3_3_1" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
<p id="answer_2fc2221016ca4bbbb4485f0d175996b3_3_1" class="answer"/>
<div id="input_2fc2221016ca4bbbb4485f0d175996b3_3_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_2fc2221016ca4bbbb4485f0d175996b3_solution_1"/>
</div></div>
<div class="action">
<input type="hidden" name="problem_id" value="problem" />
<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_2fc2221016ca4bbbb4485f0d175996b3" >
<span class="submit-label">Submit</span>
</button>
<div class="submission-feedback" id="submission_feedback_2fc2221016ca4bbbb4485f0d175996b3">
<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="2fc2221016ca4bbbb4485f0d175996b3-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="2fc2221016ca4bbbb4485f0d175996b3-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="2fc2221016ca4bbbb4485f0d175996b3-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="True">
<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-course-id="course-v1:MITx+3.15.2x+2T2017" data-runtime-class="LmsRuntime" data-init="VerticalStudentView" data-usage-id="block-v1:MITx+3.15.2x+2T2017+type@vertical+block@7e4bc26eb9a3440b80cffe7a5711fda7" data-has-score="False" data-runtime-version="1" data-block-type="vertical" data-request-token="0c3f6f54ed5411eeb4401299a322540b" data-graded="True">
<h2 class="hd hd-2 unit-title">Problem 4.2</h2>
<div class="vert-mod">
<div class="vert vert-0" data-id="block-v1:MITx+3.15.2x+2T2017+type@html+block@c49819d3776641e7827dc1f5e72c60f1">
<div class="xblock xblock-public_view xblock-public_view-html xmodule_display xmodule_HtmlBlock" data-course-id="course-v1:MITx+3.15.2x+2T2017" data-runtime-class="LmsRuntime" data-init="XBlockToXModuleShim" data-usage-id="block-v1:MITx+3.15.2x+2T2017+type@html+block@c49819d3776641e7827dc1f5e72c60f1" data-has-score="False" data-runtime-version="1" data-block-type="html" data-request-token="0c3f6f54ed5411eeb4401299a322540b" data-graded="True">
<script type="json/xblock-args" class="xblock-json-init-args">
{"xmodule-type": "HTMLModule"}
</script>
<h2>problem 4.2</h2>
<p>We can make a fiber amplifier by doping Er into a piece of silica optical fiber of length \(l\). The laser is pumped with light of wavelength \(980 nm\). Er in silica amplifies light within a wavelength range of \(1480-1520 nm\). The multilayer structure acts as a mirror. </p>
<p><img src="/assets/courseware/v1/a290ddc9c46fe7937ad8823c0ee95ef6/asset-v1:MITx+3.15.2x+2T2017+type@asset+block/315PS8Ex2_1.jpg" type="saveimage" target="[object Object]" width="778" height="163" /></p>
</div>
</div>
<div class="vert vert-1" data-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@ed1ee42b367f406d937f81cdf3e0c455">
<div class="xblock xblock-public_view xblock-public_view-problem xmodule_display xmodule_ProblemBlock" data-course-id="course-v1:MITx+3.15.2x+2T2017" data-runtime-class="LmsRuntime" data-init="XBlockToXModuleShim" data-usage-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@ed1ee42b367f406d937f81cdf3e0c455" data-has-score="True" data-runtime-version="1" data-block-type="problem" data-request-token="0c3f6f54ed5411eeb4401299a322540b" data-graded="True">
<script type="json/xblock-args" class="xblock-json-init-args">
{"xmodule-type": "Problem"}
</script>
<div id="problem_ed1ee42b367f406d937f81cdf3e0c455" class="problems-wrapper" role="group"
aria-labelledby="ed1ee42b367f406d937f81cdf3e0c455-problem-title"
data-problem-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@ed1ee42b367f406d937f81cdf3e0c455" data-url="/courses/course-v1:MITx+3.15.2x+2T2017/xblock/block-v1:MITx+3.15.2x+2T2017+type@problem+block@ed1ee42b367f406d937f81cdf3e0c455/handler/xmodule_handler"
data-problem-score="0"
data-problem-total-possible="2"
data-attempts-used="0"
data-content="
<h3 class="hd hd-3 problem-header" id="ed1ee42b367f406d937f81cdf3e0c455-problem-title" aria-describedby="block-v1:MITx+3.15.2x+2T2017+type@problem+block@ed1ee42b367f406d937f81cdf3e0c455-problem-progress" tabindex="-1">
problem
</h3>
<div class="problem-progress" id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@ed1ee42b367f406d937f81cdf3e0c455-problem-progress"></div>
<div class="problem">
<div>
<p>The fiber amplifier has a length \(l=0.2cm\) and its refractive index \(n=1.5\). The output of the amplifier as a function of wavelength is shown below:</p>
<img width="500" src="/assets/courseware/v1/8114527c1a7955b88662afa846e87525/asset-v1:MITx+3.15.2x+2T2017+type@asset+block/315PS8Ex2_2.jpg"/>
<br/>
<br/>
<p>What is the spacing of the modes (in air) of the output light? <br/> (Hint: You may find it useful to review the Laser Cavity and Modes lecture in Week 2.)</p>
<p>mode spacing (in nm):</p>
<div class="wrapper-problem-response" tabindex="-1" aria-label="Question 1" role="group"><div id="formulaequationinput_ed1ee42b367f406d937f81cdf3e0c455_2_1" class="inputtype formulaequationinput">
<div class="unanswered">
<input type="text" name="input_ed1ee42b367f406d937f81cdf3e0c455_2_1" id="input_ed1ee42b367f406d937f81cdf3e0c455_2_1" data-input-id="ed1ee42b367f406d937f81cdf3e0c455_2_1" value="" aria-describedby="status_ed1ee42b367f406d937f81cdf3e0c455_2_1" size="20"/>
<span class="trailing_text" id="trailing_text_ed1ee42b367f406d937f81cdf3e0c455_2_1"/>
<span class="status unanswered" id="status_ed1ee42b367f406d937f81cdf3e0c455_2_1" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
<p id="answer_ed1ee42b367f406d937f81cdf3e0c455_2_1" class="answer"/>
<div id="input_ed1ee42b367f406d937f81cdf3e0c455_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>
<p>How many modes exist within the emission range of the amplifier?</p>
<p>number of modes:</p>
<div class="wrapper-problem-response" tabindex="-1" aria-label="Question 2" role="group"><div id="formulaequationinput_ed1ee42b367f406d937f81cdf3e0c455_3_1" class="inputtype formulaequationinput">
<div class="unanswered">
<input type="text" name="input_ed1ee42b367f406d937f81cdf3e0c455_3_1" id="input_ed1ee42b367f406d937f81cdf3e0c455_3_1" data-input-id="ed1ee42b367f406d937f81cdf3e0c455_3_1" value="" aria-describedby="status_ed1ee42b367f406d937f81cdf3e0c455_3_1" size="20"/>
<span class="trailing_text" id="trailing_text_ed1ee42b367f406d937f81cdf3e0c455_3_1"/>
<span class="status unanswered" id="status_ed1ee42b367f406d937f81cdf3e0c455_3_1" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
<p id="answer_ed1ee42b367f406d937f81cdf3e0c455_3_1" class="answer"/>
<div id="input_ed1ee42b367f406d937f81cdf3e0c455_3_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_ed1ee42b367f406d937f81cdf3e0c455_solution_1"/>
</div></div>
<div class="action">
<input type="hidden" name="problem_id" value="problem" />
<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_ed1ee42b367f406d937f81cdf3e0c455" >
<span class="submit-label">Submit</span>
</button>
<div class="submission-feedback" id="submission_feedback_ed1ee42b367f406d937f81cdf3e0c455">
<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="ed1ee42b367f406d937f81cdf3e0c455-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="ed1ee42b367f406d937f81cdf3e0c455-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="ed1ee42b367f406d937f81cdf3e0c455-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="True">
<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@eb21b982c6ba4542b27aa89b871fa4db">
<div class="xblock xblock-public_view xblock-public_view-problem xmodule_display xmodule_ProblemBlock" data-course-id="course-v1:MITx+3.15.2x+2T2017" data-runtime-class="LmsRuntime" data-init="XBlockToXModuleShim" data-usage-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@eb21b982c6ba4542b27aa89b871fa4db" data-has-score="True" data-runtime-version="1" data-block-type="problem" data-request-token="0c3f6f54ed5411eeb4401299a322540b" data-graded="True">
<script type="json/xblock-args" class="xblock-json-init-args">
{"xmodule-type": "Problem"}
</script>
<div id="problem_eb21b982c6ba4542b27aa89b871fa4db" class="problems-wrapper" role="group"
aria-labelledby="eb21b982c6ba4542b27aa89b871fa4db-problem-title"
data-problem-id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@eb21b982c6ba4542b27aa89b871fa4db" data-url="/courses/course-v1:MITx+3.15.2x+2T2017/xblock/block-v1:MITx+3.15.2x+2T2017+type@problem+block@eb21b982c6ba4542b27aa89b871fa4db/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="eb21b982c6ba4542b27aa89b871fa4db-problem-title" aria-describedby="block-v1:MITx+3.15.2x+2T2017+type@problem+block@eb21b982c6ba4542b27aa89b871fa4db-problem-progress" tabindex="-1">
problem
</h3>
<div class="problem-progress" id="block-v1:MITx+3.15.2x+2T2017+type@problem+block@eb21b982c6ba4542b27aa89b871fa4db-problem-progress"></div>
<div class="problem">
<div>
<div class="wrapper-problem-response" tabindex="-1" aria-label="Question 1" role="group"><p>The amplifier described above (amorphous silica doped with Erbium) has a fairly broad range of emission. What would we predict might happen if we used a crystal doped with Erbium as our our amplifier material instead?</p>
<div class="choicegroup capa_inputtype" id="inputtype_eb21b982c6ba4542b27aa89b871fa4db_2_1">
<fieldset aria-describedby="status_eb21b982c6ba4542b27aa89b871fa4db_2_1">
<div class="field">
<input type="radio" name="input_eb21b982c6ba4542b27aa89b871fa4db_2_1" id="input_eb21b982c6ba4542b27aa89b871fa4db_2_1_choice_0" class="field-input input-radio" value="choice_0"/><label id="eb21b982c6ba4542b27aa89b871fa4db_2_1-choice_0-label" for="input_eb21b982c6ba4542b27aa89b871fa4db_2_1_choice_0" class="response-label field-label label-inline" aria-describedby="status_eb21b982c6ba4542b27aa89b871fa4db_2_1"> The crystal would have a broader output.
</label>
</div>
<div class="field">
<input type="radio" name="input_eb21b982c6ba4542b27aa89b871fa4db_2_1" id="input_eb21b982c6ba4542b27aa89b871fa4db_2_1_choice_1" class="field-input input-radio" value="choice_1"/><label id="eb21b982c6ba4542b27aa89b871fa4db_2_1-choice_1-label" for="input_eb21b982c6ba4542b27aa89b871fa4db_2_1_choice_1" class="response-label field-label label-inline" aria-describedby="status_eb21b982c6ba4542b27aa89b871fa4db_2_1"> The output would be similar.
</label>
</div>
<div class="field">
<input type="radio" name="input_eb21b982c6ba4542b27aa89b871fa4db_2_1" id="input_eb21b982c6ba4542b27aa89b871fa4db_2_1_choice_2" class="field-input input-radio" value="choice_2"/><label id="eb21b982c6ba4542b27aa89b871fa4db_2_1-choice_2-label" for="input_eb21b982c6ba4542b27aa89b871fa4db_2_1_choice_2" class="response-label field-label label-inline" aria-describedby="status_eb21b982c6ba4542b27aa89b871fa4db_2_1"> The crystal would have a sharper output.
</label>
</div>
<span id="answer_eb21b982c6ba4542b27aa89b871fa4db_2_1"/>
</fieldset>
<div class="indicator-container">
<span class="status unanswered" id="status_eb21b982c6ba4542b27aa89b871fa4db_2_1" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
</div><div class="solution-span">
<span id="solution_eb21b982c6ba4542b27aa89b871fa4db_solution_1"/>
</div></div>
</div>
<div class="action">
<input type="hidden" name="problem_id" value="problem" />
<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_eb21b982c6ba4542b27aa89b871fa4db" >
<span class="submit-label">Submit</span>
</button>
<div class="submission-feedback" id="submission_feedback_eb21b982c6ba4542b27aa89b871fa4db">
<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="eb21b982c6ba4542b27aa89b871fa4db-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="eb21b982c6ba4542b27aa89b871fa4db-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="eb21b982c6ba4542b27aa89b871fa4db-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="True">
<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