Magnet yog ib yam khoom siv thiab tseem ceeb, uas yog siv dav hauv lub neej txhua hnub thiab kev tsim khoom lag luam. Nyob rau hauv lub neej txhua hnub, cov hlau nplaum feem ntau siv los kho cov khoom, xws li lub qhov rooj sib nqus thiab lub khob nqus dej ntawm lub qhov rooj tub yees, uas tuaj yeem ua kom cov khoom noj tshiab thiab kev nyab xeeb. Tsis tas li ntawd, cov hlau nplaum kuj tau siv los ua cov khoom dai ntawm rooj tog ornaments thiab cov duab tuav ntawm cov duab phab ntsa, coj kev zoo nkauj thiab yooj yim rau lub neej. Hauv kev tsim khoom, cov hlau nplaum yog siv ntau dua. Cov hlau nplaum yog dav siv nyob rau hauv motors thiab generators, siv magnetic quab yuam kom ua tau lub zog hloov dua siab tshiab thiab txhua yam motion. Tsis tas li ntawd, cov hlau nplaum kuj tau siv rau hauv cov khoom siv sensors thiab cov cuab yeej tshawb nrhiav kom tau txais cov ntaub ntawv thiab saib xyuas kev hloov pauv ib puag ncig los ntawm kev hnov cov kev hloov pauv hauv cov hlau nplaum. Piv txwv li, lub compass yog lub sensor uas siv hlau nplaum los pab tib neeg taw qhia lawv tus kheej.