Cov Greeks qub thiab Suav pom tias muaj ib lub pob zeb loj tshaj plaws hauv lub cev, hu ua "cov hlau nplaum." Lub pob zeb no tuaj yeem tuaj tos me me hlau thiab ib txwm taw tes rau qhov kev taw qhia tom qab qw qw.
Cov voj voog siv thaum ntxov no siv cov hlau nplaum no raws li lawv qhov koob tshaj plaws kom pom qhov kev taw qhia hauv hiav txwv. Tom qab txhiab xyoo ntawm txoj kev loj hlob, hnub no lub nplhaib tau dhau los ua ib qho tseem ceeb hauv peb lub neej. Cov nyhuv tib yam li cov magnetite tau ua tiav los ntawm kev siv cov khoom sib txawv ntawm cov khoom sib txawv, thiab kev sib zog sib nqus sib nqus. Cov hlau nplaum loj heev hauv xyoo pua 18th, tab sis cov txheej txheem ntawm kev sib zog sib nqus cov khoom sib nqus tau qeeb qeeb mus txog 1920s thaum Alnico tau tsim. Tom qab ntawd, Ferrite tau tsim nyob rau xyoo 1950, thiab lub ntiaj teb tsis tshua muaj hlau nplaum tau tsim nyob rau xyoo 1970s [Lub Xeeb Ntim Lub Ntiaj Teb hauv ntiaj teb nrog NdFeB thiab SmCo). Txij ntawm no mus, cov tshuab hlau nplaum tsim tau sai, thiab cov khoom sib nqus tau ua cov khoom sib cog lus dua. Dab tsi yog qhov kev taw qhia (orientation)? Feem ntau cov khoom sib nqus tuaj yeem magnetized mus rau kev xyuam xim nyob rau tib qho kev coj ua, ib qho kev hu ua "direction of direction magnetization" (orientation direction).
Ib tug hlau nplaum uas tsis muaj kev taw qhia txog kev taw qhia (tseem hu ua isotropic magnet) ntau zog tshaj li qhov kev taw qhia cov hlau nplaum (tseem hu ua ib qho anisotropic magnet). Tus qauv "North-Arctic" yog dab tsi? "Arctic" txhais tias yog lub qaum teb ntawm lub ntiaj teb taw tes rau sab qaum teb ncej ntawm lub ntiaj teb tom qab lub nplhaib tig rov qab dawb. Ib yam li ntawd, sab qab teb ncej ntawm cov hlau nplaum kuj taw rau sab qab teb ncej ntawm lub ntiaj teb. Yuav ua li cas qhia tus ncej sab qaum teb ntawm cov hlau nplaum tsis tas kos? Obviously nws yog tsis paub qhov txawv ntawm qhov muag. Koj tuaj yeem siv lub koob ntiv taw los lo rau cov hlau nplaum, thiab tus pointer mus rau sab qaum teb ncej ntawm lub ntiaj teb taw tes rau sab qab teb ncej ntawm cov hlau nplaum. Yuav ua li cas daws thiab khaws cov hlau nplaum kom zoo? Txhua zaus yuav tsum xyuam xim, raws li cov hlau nplaum yuav lo ua ke thiab yuav thim koj cov ntiv tes. Thaum cov hlau nplaum ntub dej ntau, tej zaum cov hlau nplaum yuav raug kev cuam tshuam los ntawm kev sib tsoo (qhov chaw tiaj nyom tawg los yog tawg ua tawg). Khaws cov hlau nplaum tawm ntawm cov khoom uas yooj yim magnetized, xws li cov duab Disk, credit card, computer monitors, watches, cov xov tooj ntawm tes, cov khoom siv kho mob, thiab lwm yam. Khaws cov nplhaib tawm ntawm lub pacemaker.
Rau cov hlau nplaum loj, yuav tsum muab cov yas los yog cov duab los sib txuas rau txhua ntu kom paub meej tias cov hlau nplaum yuav raug muab cais yooj yim. Lub hlau nplaum yuav tsum tau muab cia rau hauv qhov chaw qhuav, qhov kub thiab txias ntawm qhov chaw kom ntau li ntau tau. Yuav ua li cas thiaj ncav tau sib cais sib nqus? Tsuas yog cov ntaub ntawv uas yuav muaj attracted rau cov hlau nplaum yuav ua haujlwm los thaiv lub nrag hlau, thiab lub thicker cov khoom, zoo dua qhov sib sib zog nqus sib cais. Dab tsi yog qhov muaj zog tshaj hlau nplaum?
Tam sim no, qhov kev ua tau zoo tshaj plaws hlau nplaum yog lub ntiaj teb tsis tshua muaj hlau nplaum, thiab nyob hauv lub ntiaj teb tsis tshua muaj hlau nplaum, neodymium hlau boron yog cov khoob khoob loj tshaj. Txawm li cas los xij, nyob rau hauv ib puag ncig 200 degrees Celsius, samarium cobalt yog cov khoob khoob loj tshaj. Hom hlau nplaum: hlau nplaum, yuav tsum tau hu ua hlau nplaum hlau, Askiv hlau nplaum, sib nqus hlau tam sim no muab faib ua ob pawg loj, ib qho yog sib nqus nplaum, ib qho yog sib zog nqus; nplua nuj hlau xws li silicon hlau thiab cov hlau nqus hlau nplhaib; Sib zog nqus hlau nplaum xws li cov xim noom qe nickel Cobalt, samarium cobalt, ferrite thiab neodymium hlau boron, cov uas kim tshaj plaws yog samarium cobalt hlau nplaum, qhov pheej yig tshaj yog ferrite hlau nplaum, qhov kev kawm siab tshaj plaws yog NdFeB hlau, tab sis qhov kev ua haujlwm yog qhov ruaj khov, Coefficient yog AlNiCo cov hlau nplaum, cov neeg siv tau xaiv ntau hom khoom sib nqus sib txawv raws li kev xav tau sib txawv.
Yuav ua li cas txheeb xyuas cov kev ua tau zoo ntawm cov hlau nplaum? Muaj ntau qhov peb ua tau tsis zoo los txiav txim siab txog kev ua tiav ntawm cov hlau nplaum: Remanent Br: Lub dag lub nplhaib nyob rau ntawm qhov kev ua kom haum, thiab tom qab sab nraud magnetic teb raug tshem tawm, qhov khaws cia Br yog hu ua qhov seem qis ntawm kev sib nqus. Coercive quab yuam HC: Lub B ntawm cov cuab yeej txuas mus tas li magnetized rau cov kev kho mob saturation yog txo kom tsawg dua xoom. Qhov yuav tsum tau rov qab ua tau nrawm dua magnetic field lub zog yog hu ua tus quab yuam sib nqus, uas yog hu ua coercive force zog khoom BiH: nruab nrab yog cov hlau nplaum nyob hauv cov pa nruab nrab. Qhov sib txawv ntawm qhov sib txawv ntawm qhov chaw (qhov ob qhov sib nqus ncej ntawm cov hlau nplaum), uas yog, lub zog magnetostatic rau ib chav tsev ntim ntawm cov pa nruab nrab. Txij li thaum lub zog no sib npaug rau cov khoom ntawm Bm thiab Hm ntawm cov hlau nplaum, nws yog hu ua cov khoom hluav taws xob sib nqus. Sib khom qhov chaw: Qhov chaw uas khwv tau ua rau ntawm txoj kab sib nqus ncej yog lub sib nqus field.
Qhov sib nqus field: Qhov sib txawv ntawm qhov sib txawv ntawm ib txoj hauj lwm nyob rau ntawm qhov chaw mus tas li xaiv cov hlau nplaum? Ua ntej yuav txiav txim siab seb cov hlau nplaum twg xaiv, lub luag hauj lwm yog cov hlau nplaum yuav tsum ua si li cas? Lub luag haujlwm tseem ceeb: txav khoom, txav khoom lossis khoom nyom. Cov duab ntawm cov hlau nplaum uas yuav tsum tau: ib hom duab disk, ib lub zoo, ib hom duab square, ib pobzeb duab los yog ib tus qauv tshwj xeeb. Qhov loj ntawm qhov yuav tsum tau hlau nplaum: ntev, dav, qhov siab, lub cheeb thiab kam, thiab lwm yam.
