Umlelesa
isakhi soqobo
soTho
esibangela uTho olulelesiwe ukuba lungcwethe
isiphoqi
lapho lubekwa ewongweni lenzubawonga. Umlelesa ungaba
ophikayo
noma
ovumayo
(imvama uthwalwa
izinelesi
ne
zintunge
). Imilelesa efanayo iyadudulana futhi imilelesa engafani iyahuhana. Into engenawo umlelesa owanele ibizwa engachemile
(neutral)
. Ulwazi lwangaphambilini lokuthi iziqa ezilelesiwe zinanana kanjani manje selubizwa ngokuthi ezomdikiwenzuba zakudala
(classical electrodynamics)
, futhi zisanembile ezinkingeni ezidinga ukucubungulwa zomthelela womngako
(quantum effects)
.
Umlelesa wamazuba uyisakhi esilondoloziwe; umlelesa oyisamba wesimiso esigonqiwe, inani lomlelesa ovumayo ongenakushintsha, osuswe enanini lomlelesa ophikayo. Umlelesa wamazuba uthwalwa
izinhlayiyana zechwe
.
Othweni
oluvamile, umlelesa ophikayo uthwalwa
izinzuba
, bese umlelesa ovumayo uthwalwe
izinelesi
endenini yeChwe. Uma kunezinzuba eziningi kunezinelezi ocezwini lotho, lolotho luzoba nomlelesa ophikayo, uma zimbalwa izinzuba, luzoba nomlelesa ovumayo, futhi uma izinzuba nezinelesi zilingana ngenani, utho luzoba olungachemile.