電(dian)(dian)(dian)阻(zu)器(qi)是限制電(dian)(dian)(dian)流的(de)元件，通(tong)常(chang)簡稱(cheng)為電(dian)(dian)(dian)阻(zu)，是一種最(zui)常(chang)用的(de)電(dian)(dian)(dian)子元件，普遍應用在各(ge)類電(dian)(dian)(dian)子電(dian)(dian)(dian)路中。不(bu)但金屬(shu)導體(ti)有電(dian)(dian)(dian)阻(zu)，其(qi)他物(wu)體(ti)也有電(dian)(dian)(dian)阻(zu)。

簡(jian)單來說，電(dian)(dian)(dian)(dian)(dian)阻(zu)就(jiu)是(shi)指(zhi)電(dian)(dian)(dian)(dian)(dian)流(liu)在電(dian)(dian)(dian)(dian)(dian)路(lu)中所(suo)遇到(dao)的阻(zu)力(li)，或者說是(shi)指(zhi)物體對電(dian)(dian)(dian)(dian)(dian)流(liu)的阻(zu)礙才能(neng)。電(dian)(dian)(dian)(dian)(dian)阻(zu)越(yue)大，電(dian)(dian)(dian)(dian)(dian)流(liu)所(suo)遭(zao)到(dao)的阻(zu)力(li)就(jiu)越(yue)大，因而電(dian)(dian)(dian)(dian)(dian)流(liu)就(jiu)越(yue)小(xiao)(xiao)。反之，電(dian)(dian)(dian)(dian)(dian)阻(zu)越(yue)小(xiao)(xiao)，電(dian)(dian)(dian)(dian)(dian)流(liu)所(suo)遭(zao)到(dao)的阻(zu)力(li)就(jiu)越(yue)小(xiao)(xiao)，因而電(dian)(dian)(dian)(dian)(dian)流(liu)就(jiu)越(yue)大。

電阻(zu)的(de)符號是(shi)“R”。電阻(zu)的(de)單位(wei)為(wei)歐(ou)姆，簡稱歐(ou)，用(yong)(yong)字母“Ω”表示(shi)。常(chang)用(yong)(yong)的(de)電阻(zu)單位(wei)還有千歐(ou)姆（KΩ），兆(zhao)歐(ou)姆（MΩ）。