// Numbas version: exam_results_page_options
{"name": "DC Shunt Motor", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"name": "DC Shunt Motor", "tags": [], "metadata": {"description": "", "licence": "None specified"}, "statement": "<p>The following test data was measured for a separately excited DC machine operating at a speed of $\\var{Ntest}\\ rpm$ with an open circuit armature:</p>\n<p></p>\n<table border=\"1\" height=\"167\" style=\"margin-left: auto; margin-right: auto; width: 1020px;\">\n<tbody>\n<tr>\n<td style=\"width: 90.5556px;\">\n<p><strong>Field Current</strong></p>\n<p><strong>IF [A]</strong></p>\n</td>\n<td style=\"text-align: center; width: 58.3333px;\">\n<p>0</p>\n</td>\n<td style=\"text-align: center; width: 61.6667px;\">\n<p>0.1</p>\n</td>\n<td style=\"text-align: center; width: 67.2222px;\">\n<p>0.2</p>\n</td>\n<td style=\"text-align: center; width: 71.6667px;\">\n<p>0.3</p>\n</td>\n<td style=\"text-align: center; width: 66.1111px;\">\n<p>0.4</p>\n</td>\n<td style=\"text-align: center; width: 66.1111px;\">\n<p>0.5</p>\n</td>\n<td style=\"text-align: center; width: 67.2222px;\">\n<p>0.6</p>\n</td>\n<td style=\"text-align: center; width: 67.2222px;\">\n<p>0.7</p>\n</td>\n<td style=\"text-align: center; width: 67.2222px;\">\n<p>0.8</p>\n</td>\n<td style=\"text-align: center; width: 65px;\">\n<p>0.9</p>\n</td>\n<td style=\"text-align: center; width: 77.2222px;\">\n<p>1.0</p>\n</td>\n</tr>\n<tr>\n<td style=\"width: 90.5556px;\">\n<p><strong>Armature Voltage</strong></p>\n<p><strong>VA [V]</strong></p>\n</td>\n<td style=\"width: 58.3333px; text-align: center;\">{VA[0]}</td>\n<td style=\"width: 61.6667px; text-align: center;\">{VA[1]}</td>\n<td style=\"width: 67.2222px; text-align: center;\">{VA[2]}</td>\n<td style=\"width: 71.6667px; text-align: center;\">{VA[3]}</td>\n<td style=\"width: 66.1111px; text-align: center;\">{VA[4]}</td>\n<td style=\"width: 66.1111px; text-align: center;\">{VA[5]}</td>\n<td style=\"width: 67.2222px; text-align: center;\">{VA[6]}</td>\n<td style=\"width: 67.2222px; text-align: center;\">{VA[7]}</td>\n<td style=\"width: 67.2222px; text-align: center;\">{VA[8]}</td>\n<td style=\"width: 65px; text-align: center;\">{VA[9]}</td>\n<td style=\"width: 77.2222px; text-align: center;\">{VA[10]}</td>\n</tr>\n</tbody>\n</table>\n<p style=\"text-align: center;\"></p>\n<p>The&nbsp;intrinsic resistances are:</p>\n<p>Field Resistance:&nbsp;$R_F = \\var{RF}\\ \\Omega&nbsp;$</p>\n<p>Armature Resistance:&nbsp;$R_A = \\var{RA}\\&nbsp; \\Omega&nbsp;$&nbsp;</p>\n<p>The machine is then connected as a shunt motor to a&nbsp;supply providing $\\var{VS}\\ V$.&nbsp;The motor is used to lift a weight which creates a torque of $\\var{T}\\ Nm$.</p>", "advice": "", "rulesets": {}, "extensions": [], "builtin_constants": {"e": true, "pi,\u03c0": true, "i": true}, "constants": [], 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"adaptiveMarkingPenalty": 0, "exploreObjective": null, "prompt": "<p>What is the magnetism on the machine?</p>\n<p>$k_a \\phi = $ [[0]]</p>", "stepsPenalty": 0, "steps": [{"type": "information", "useCustomName": false, "customName": "", "marks": 0, "scripts": {}, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "showCorrectAnswer": true, "showFeedbackIcon": true, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "nextParts": [], "suggestGoingBack": false, "adaptiveMarkingPenalty": 0, "exploreObjective": null, "prompt": "<ul>\n<li>Find the field current, $I_F$, using Ohm's Law.</li>\n<li>Find the speed and voltage during testing from the data at this field current.</li>\n<li>Convert the speed from $N$ in rpm to $\\omega$ in rad/s.</li>\n<li>Fill these values into $e_a=k_a\\phi\\omega$ to get the magnetism, $k_a\\phi$.</li>\n</ul>"}], "gaps": [{"type": "numberentry", "useCustomName": true, "customName": "Magnetism", "marks": 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"exploreObjective": null, "prompt": "<p>How much current is it drawing from the supply?</p>\n<p>$I_S$ =&nbsp;[[0]] $ A $</p>", "stepsPenalty": 0, "steps": [{"type": "information", "useCustomName": false, "customName": "", "marks": 0, "scripts": {}, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "showCorrectAnswer": true, "showFeedbackIcon": true, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "nextParts": [], "suggestGoingBack": false, "adaptiveMarkingPenalty": 0, "exploreObjective": null, "prompt": "<ul>\n<li>Calcuate the field current, $I_F$, as before using Ohm's Law.</li>\n<li>Find the armature current from $T=k_a\\phi I_A$.</li>\n<li>Get the supply current from Kirchhoff's Current Law.</li>\n</ul>"}], "gaps": [{"type": "numberentry", "useCustomName": true, "customName": "Current", "marks": "10", "scripts": {}, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "showCorrectAnswer": 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