{"product_id":"when-heat-defeats-magnetism","title":"When Heat Defeats Magnetism","description":"\u003ch2\u003e\n\u003cmeta content=\"text\/html; charset=utf-8\" http-equiv=\"content-type\"\u003eA paper clip hangs in midair, seemingly defying gravity.\u003c\/h2\u003e\n\u003cp data-start=\"819\" data-end=\"930\"\u003eA magnet pulls it upward while a thread pulls it downward. The forces balance, creating a delicate equilibrium.\u003c\/p\u003e\n\u003cp data-start=\"932\" data-end=\"956\"\u003eNow comes the challenge:\u003c\/p\u003e\n\u003cblockquote data-start=\"958\" data-end=\"1030\"\u003e\n\u003cp data-start=\"960\" data-end=\"1030\"\u003eCan heat destroy the magnetic attraction and make the paper clip fall?\u003c\/p\u003e\n\u003c\/blockquote\u003e\n\u003ch2 data-start=\"1037\" data-end=\"1060\"\u003eWhat You Will Observe\u003c\/h2\u003e\n\u003cp data-start=\"1062\" data-end=\"1121\"\u003eA ring magnet is suspended with its symmetry axis vertical.\u003c\/p\u003e\n\u003cp data-start=\"1123\" data-end=\"1164\"\u003eA paper clip is tied to a thread so that:\u003c\/p\u003e\n\u003cul data-start=\"1166\" data-end=\"1288\"\u003e\n\u003cli data-start=\"1166\" data-end=\"1193\"\u003eGravity pulls it downward\u003c\/li\u003e\n\u003cli data-start=\"1194\" data-end=\"1231\"\u003eMagnetic attraction pulls it upward\u003c\/li\u003e\n\u003cli data-start=\"1232\" data-end=\"1288\"\u003eThe clip remains suspended without touching the magnet\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp data-start=\"1327\" data-end=\"1368\"\u003eThe paper clip appears to float in space.\u003c\/p\u003e\n\u003ch2 data-start=\"1375\" data-end=\"1391\"\u003ePrediction\u003c\/h2\u003e\n\u003cp data-start=\"1393\" data-end=\"1471\"\u003eMost magnetic materials lose their magnetic behaviour when heated sufficiently.\u003c\/p\u003e\n\u003cp data-start=\"1473\" data-end=\"1547\"\u003eThis happens at a characteristic temperature called the Curie temperature.\u003c\/p\u003e\n\u003cp data-start=\"1549\" data-end=\"1577\"\u003eBelow the Curie temperature:\u003c\/p\u003e\n\u003cul data-start=\"1579\" data-end=\"1647\"\u003e\n\u003cli data-start=\"1579\" data-end=\"1619\"\u003eAtomic magnetic moments tend to align.\u003c\/li\u003e\n\u003cli data-start=\"1620\" data-end=\"1647\"\u003eMagnetic order dominates.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp data-start=\"1649\" data-end=\"1677\"\u003eAbove the Curie temperature:\u003c\/p\u003e\n\u003cul data-start=\"1679\" data-end=\"1769\"\u003e\n\u003cli data-start=\"1679\" data-end=\"1718\"\u003eThermal agitation disrupts alignment.\u003c\/li\u003e\n\u003cli data-start=\"1719\" data-end=\"1740\"\u003eDisorder dominates.\u003c\/li\u003e\n\u003cli data-start=\"1741\" data-end=\"1769\"\u003eFerromagnetism disappears.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp data-start=\"1771\" data-end=\"1844\"\u003eThe transition is one of the most important phase transitions in physics.\u003c\/p\u003e\n\u003ch2 data-start=\"1851\" data-end=\"1864\"\u003ePhysics\u003c\/h2\u003e\n\u003cp data-start=\"1866\" data-end=\"1934\"\u003eThe competition is between magnetic interactions and thermal motion.\u003c\/p\u003e\n\u003cp data-start=\"1936\" data-end=\"1955\"\u003eAt low temperature:\u003c\/p\u003e\n\u003cul data-start=\"1957\" data-end=\"1979\"\u003e\n\u003cli data-start=\"1957\" data-end=\"1979\"\u003eMagnetic order wins.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp data-start=\"1981\" data-end=\"2001\"\u003eAt high temperature:\u003c\/p\u003e\n\u003cul data-start=\"2003\" data-end=\"2027\"\u003e\n\u003cli data-start=\"2003\" data-end=\"2027\"\u003eThermal disorder wins.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp data-start=\"2029\" data-end=\"2086\"\u003eThe critical temperature is called the Curie temperature. \u003cmeta content=\"text\/html; charset=utf-8\" http-equiv=\"content-type\"\u003eAbove this temperature, a ferromagnetic material becomes only weakly magnetic.\u003c\/p\u003e\n\u003ch2 data-start=\"2212\" data-end=\"2243\"\u003eAttempt 1: Electrical Heating\u003c\/h2\u003e\n\u003cp data-start=\"2245\" data-end=\"2338\"\u003eThe paper clip was bent so that a battery could be connected across it using crocodile clips.\u003c\/p\u003e\n\u003cp data-start=\"2340\" data-end=\"2373\"\u003eCurrent flowed through the metal.\u003c\/p\u003e\n\u003cp data-start=\"2375\" data-end=\"2402\"\u003eThe expectation was simple:\u003c\/p\u003e\n\u003col data-start=\"2404\" data-end=\"2505\"\u003e\n\u003cli data-start=\"2404\" data-end=\"2432\"\u003eCurrent produces heating.\u003c\/li\u003e\n\u003cli data-start=\"2433\" data-end=\"2454\"\u003eTemperature rises.\u003c\/li\u003e\n\u003cli data-start=\"2455\" data-end=\"2486\"\u003eMagnetic attraction weakens.\u003c\/li\u003e\n\u003cli data-start=\"2487\" data-end=\"2505\"\u003eThe clip falls.\u003c\/li\u003e\n\u003c\/ol\u003e\n\u003cp data-start=\"2507\" data-end=\"2541\"\u003eBut something unexpected happened.\u003c\/p\u003e\n\u003cp data-start=\"2543\" data-end=\"2588\"\u003eThe clip became warm, yet remained suspended.\u003c\/p\u003e\n\u003cp data-start=\"2590\" data-end=\"2653\"\u003ePerhaps the temperature never approached the Curie temperature.\u003c\/p\u003e\n\u003cp data-start=\"2655\" data-end=\"2702\"\u003eOr perhaps something more subtle was occurring.\u003c\/p\u003e\n\u003ch2 data-start=\"2709\" data-end=\"2736\"\u003eAttempt 2: Candle Heating\u003c\/h2\u003e\n\u003cp data-start=\"2738\" data-end=\"2768\"\u003eThe next step was more direct.\u003c\/p\u003e\n\u003cp data-start=\"2770\" data-end=\"2817\"\u003eA candle flame was used to heat the paper clip.\u003c\/p\u003e\n\u003cp data-start=\"2819\" data-end=\"2859\"\u003eThe clip became much hotter than before.\u003c\/p\u003e\n\u003cp data-start=\"2861\" data-end=\"2892\"\u003eAgain the prediction was clear:\u003c\/p\u003e\n\u003cblockquote data-start=\"2894\" data-end=\"2959\"\u003e\n\u003cp data-start=\"2896\" data-end=\"2959\"\u003eHeat the clip enough, remove its magnetism, and it should fall.\u003c\/p\u003e\n\u003c\/blockquote\u003e\n\u003cp data-start=\"2961\" data-end=\"2987\"\u003eBut it still did not fall.\u003c\/p\u003e\n\u003cp data-start=\"2989\" data-end=\"3021\"\u003eThe result raises new questions.\u003c\/p\u003e\n\u003ch2 data-start=\"3028\" data-end=\"3041\"\u003eMystery\u003c\/h2\u003e\n\u003cp data-start=\"3043\" data-end=\"3076\"\u003eWhy did the clip remain attached?\u003c\/p\u003e\n\u003cp data-start=\"3078\" data-end=\"3106\"\u003eSeveral possibilities exist:\u003c\/p\u003e\n\u003ch3 data-start=\"3108\" data-end=\"3125\"\u003ePossibility 1\u003c\/h3\u003e\n\u003cp data-start=\"3126\" data-end=\"3171\"\u003eThe clip never reached its Curie temperature.\u003c\/p\u003e\n\u003cp data-start=\"3173\" data-end=\"3244\"\u003eMany steels have Curie temperatures of several hundred degrees Celsius.\u003c\/p\u003e\n\u003cp data-start=\"3246\" data-end=\"3310\"\u003eA candle flame may not have heated the entire clip sufficiently.\u003c\/p\u003e\n\u003ch3 data-start=\"3312\" data-end=\"3329\"\u003ePossibility 2\u003c\/h3\u003e\n\u003cp data-start=\"3330\" data-end=\"3363\"\u003eOnly part of the clip became hot.\u003c\/p\u003e\n\u003cp data-start=\"3365\" data-end=\"3412\"\u003eThe cooler sections may have remained magnetic.\u003c\/p\u003e\n\u003ch3 data-start=\"3414\" data-end=\"3431\"\u003ePossibility 3\u003c\/h3\u003e\n\u003cp data-start=\"3432\" data-end=\"3525\"\u003eThe magnetic field from the ring magnet may still induce magnetization in the cooler regions.\u003c\/p\u003e\n\u003ch3 data-start=\"3527\" data-end=\"3544\"\u003ePossibility 4\u003c\/h3\u003e\n\u003cp data-start=\"3545\" data-end=\"3625\"\u003eThe material of the paper clip may not behave exactly as expected under heating.\u003c\/p\u003e\n\u003ch3 data-start=\"3627\" data-end=\"3644\"\u003ePossibility 5\u003c\/h3\u003e\n\u003cp data-start=\"3645\" data-end=\"3714\"\u003eThe Curie temperature may have been reached only briefly and locally.\u003c\/p\u003e\n\u003ch2 data-start=\"3721\" data-end=\"3737\"\u003eYour Challenge\u003c\/h2\u003e\n\u003cp data-start=\"3739\" data-end=\"3788\"\u003eThis experiment is intentionally left unfinished.\u003c\/p\u003e\n\u003cp data-start=\"3790\" data-end=\"3817\"\u003eCan you make the clip fall?\u003c\/p\u003e\n\u003cp data-start=\"3819\" data-end=\"3847\"\u003ePossible approaches include:\u003c\/p\u003e\n\u003cul data-start=\"3849\" data-end=\"4065\"\u003e\n\u003cli data-start=\"3849\" data-end=\"3871\"\u003eUsing a butane torch\u003c\/li\u003e\n\u003cli data-start=\"3872\" data-end=\"3895\"\u003eUsing a propane flame\u003c\/li\u003e\n\u003cli data-start=\"3896\" data-end=\"3928\"\u003eMeasuring temperature directly\u003c\/li\u003e\n\u003cli data-start=\"3929\" data-end=\"3966\"\u003eTrying different magnetic materials\u003c\/li\u003e\n\u003cli data-start=\"3967\" data-end=\"3998\"\u003eTesting different paper clips\u003c\/li\u003e\n\u003cli data-start=\"3999\" data-end=\"4023\"\u003eUsing stronger magnets\u003c\/li\u003e\n\u003cli data-start=\"4024\" data-end=\"4065\"\u003eRecording the experiment in slow motion\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp data-start=\"4067\" data-end=\"4118\"\u003eThe goal is not simply to reproduce a known result.\u003c\/p\u003e\n\u003cp data-start=\"4120\" data-end=\"4185\"\u003eThe goal is to investigate why the expected result did not occur.\u003c\/p\u003e\n\u003ch3 data-start=\"4224\" data-end=\"4268\"\u003e\u003cstrong\u003eThis experiment connects several deep ideas:\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cdiv class=\"TyagGW_tableContainer\"\u003e\n\u003cdiv class=\"group TyagGW_tableWrapper flex flex-col-reverse w-fit\" tabindex=\"-1\"\u003e\n\u003ctable data-start=\"4270\" data-end=\"4629\" class=\"w-fit min-w-(--thread-content-width)\"\u003e\n\u003cthead data-start=\"4270\" data-end=\"4298\"\u003e\n\u003ctr data-start=\"4270\" data-end=\"4298\"\u003e\n\u003cth data-start=\"4270\" data-end=\"4280\" data-col-size=\"sm\" class=\"last:pe-10\"\u003eConcept\u003c\/th\u003e\n\u003cth data-start=\"4280\" data-end=\"4298\" data-col-size=\"md\" class=\"last:pe-10\"\u003eWhat You Learn\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody data-start=\"4328\" data-end=\"4629\"\u003e\n\u003ctr data-start=\"4328\" data-end=\"4389\"\u003e\n\u003ctd data-start=\"4328\" data-end=\"4340\" data-col-size=\"sm\"\u003eMagnetism\u003c\/td\u003e\n\u003ctd data-col-size=\"md\" data-start=\"4340\" data-end=\"4389\"\u003eMagnetic attraction and induced magnetization\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr data-start=\"4390\" data-end=\"4439\"\u003e\n\u003ctd data-start=\"4390\" data-end=\"4408\" data-col-size=\"sm\"\u003eThermal Physics\u003c\/td\u003e\n\u003ctd data-col-size=\"md\" data-start=\"4408\" data-end=\"4439\"\u003eHeating and energy transfer\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr data-start=\"4440\" data-end=\"4481\"\u003e\n\u003ctd data-start=\"4440\" data-end=\"4460\" data-col-size=\"sm\"\u003ePhase Transitions\u003c\/td\u003e\n\u003ctd data-col-size=\"md\" data-start=\"4460\" data-end=\"4481\"\u003eCurie temperature\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr data-start=\"4482\" data-end=\"4517\"\u003e\n\u003ctd data-start=\"4482\" data-end=\"4496\" data-col-size=\"sm\"\u003eEquilibrium\u003c\/td\u003e\n\u003ctd data-start=\"4496\" data-end=\"4517\" data-col-size=\"md\"\u003eBalance of forces\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr data-start=\"4518\" data-end=\"4584\"\u003e\n\u003ctd data-start=\"4518\" data-end=\"4538\" data-col-size=\"sm\"\u003eMaterials Science\u003c\/td\u003e\n\u003ctd data-col-size=\"md\" data-start=\"4538\" data-end=\"4584\"\u003eProperties of steel and magnetic materials\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr data-start=\"4585\" data-end=\"4629\"\u003e\n\u003ctd data-start=\"4585\" data-end=\"4605\" data-col-size=\"sm\"\u003eScientific Method\u003c\/td\u003e\n\u003ctd data-col-size=\"md\" data-start=\"4605\" data-end=\"4629\"\u003ePredictions can fail\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003cp\u003e\u003cmeta content=\"text\/html; charset=utf-8\" http-equiv=\"content-type\"\u003eA surprising result is often more valuable than a successful demonstration.\u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e","brand":"Geometers","offers":[{"title":"Default Title","offer_id":45914121896072,"sku":null,"price":0.0,"currency_code":"INR","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0725\/3891\/4952\/files\/1_729266dc-df11-4a9d-968c-8d41db514a38.jpg?v=1780031212","url":"https:\/\/geometers.in\/products\/when-heat-defeats-magnetism","provider":"Geometers","version":"1.0","type":"link"}