Lub transformer yog ib yam khoom siv uas siv lub hauv paus ntsiab lus ntawm electromagnetic induction los hloov alternating tam sim no voltage. Nws cov khoom tseem ceeb yog thawj kauj, theem ob, thiab cov tub ntxhais hlau (magnetic core).
Hauv cov khoom siv hluav taws xob thiab hluav taws xob hluav taws xob, cov khoom siv hluav taws xob feem ntau yog siv rau theem voltage -up/step-down, impedance matching, thiab kev ruaj ntseg cais. Hauv cov tshuab hluav taws xob, txawm hais tias lub kauj txav los ntawm qhov chaw sib nqus los yog qhov chaw sib nqus txav los ntawm lub kauj vab, lub zog hluav taws xob yog induced hauv lub kauj. Nyob rau hauv ob qho tib si, tus nqi ntawm cov hlau nplaum flux tseem nyob tas li, tab sis tus naj npawb ntawm cov hlau nplaum sib txuas nrog cov coil hloov; qhov no yog lub hauv paus ntsiab lus ntawm kev sib nrig sib induction. Transformer yog ib yam khoom siv hluav taws xob sib nqus induction los hloov voltage, tam sim no, thiab impedance.