Kusekethe ye-AC, kunezinhlobo ezimbili zamandla kagesi anikezwa umthwalo ovela kugesi: enye ingamandla asebenzayo kanti enye ingamandla asebenzayo. Uma umthwalo ungumthwalo ophikisayo, amandla asetshenziswayo angamandla asebenzayo, uma umthwalo ungumthwalo othwala amandla noma obangela ukuguquka, ukusetshenziswa kwawo kungamandla asebenzayo. I-voltage yamandla asebenzayo kanye nogesi esigabeni esifanayo (amandla e-AC umehluko phakathi kwamandla asebenzayo nasebenzayo), lapho i-voltage idlula ugesi, ingamandla ayo asebenzayo avuselela ukuguquka; uma ugesi udlula ugesi, ingamandla ayo asebenzayo avuselela ukuguquka.

Amandla asebenzayo amandla kagesi adingekayo ukugcina ukusebenza okuvamile kwemishini kagesi, okungukuthi, ukuguqulwa kwamandla kagesi abe ezinye izinhlobo zamandla (amandla omshini, amandla okukhanya, ukushisa) kwamandla kagesi. Isibonelo: ama-kilowatts angu-5.5 enjini kagesi angama-kilowatts angu-5.5 wamandla kagesi aguqulwa abe amandla omshini, aqhube ipompo ukuze ipompe amanzi noma umshini wokubhula; imishini yokukhanyisa ehlukahlukene izoguqulwa ibe amandla okukhanya, ukuze abantu baphile futhi basebenze ngokukhanyisa.

Amandla asebenzayo awabonakali; ngamandla kagesi asetshenziselwa ukushintshanisa amasimu kagesi namagnetic ngaphakathi kwesekethe kanye nokusungula nokugcina insimu yamagnetic emishinini kagesi. Ayisebenzi ngaphandle, kodwa iguqulwa ibe ezinye izinhlobo zamandla. Noma iyiphi idivayisi kagesi ene-coil kagesi isebenzisa amandla asebenzayo ukuze isungule insimu yamagnetic. Isibonelo, isibani se-fluorescent esingu-40-watt sidinga ama-watt angaphezu kuka-40 wamandla asebenzayo (i-ballast nayo idinga ukusebenzisa ingxenye yamandla asebenzayo) ukuze ikhiphe ukukhanya, kodwa futhi idinga amandla asebenzayo angaba ngu-80 ukuze i-ballast coil isungule insimu yamagnetic eshintshanayo. Ngoba ayenzi umsebenzi wangaphandle, kodwa ibizwa ngokuthi “i-reactive”.