簡單的(de)講，電源電動勢(shi)是(shi)指單位正電荷從(cong)電池(chi)的(de)負極到(dao)正極由非靜電力所作的(de)功。其數值(zhi)也可以(yi)描(miao)述為(wei)電池(chi)內各相界(jie)面上(shang)電勢(shi)差的(de)代數和(he)。

即電(dian)(dian)(dian)(dian)(dian)(dian)子運動(dong)的(de)(de)(de)(de)(de)趨勢，能(neng)(neng)夠克服導(dao)體(ti)(ti)電(dian)(dian)(dian)(dian)(dian)(dian)阻對電(dian)(dian)(dian)(dian)(dian)(dian)流的(de)(de)(de)(de)(de)阻力，使電(dian)(dian)(dian)(dian)(dian)(dian)荷在閉合的(de)(de)(de)(de)(de)導(dao)體(ti)(ti)回(hui)路(lu)中(zhong)流動(dong)的(de)(de)(de)(de)(de)一種(zhong)作(zuo)用。這種(zhong)作(zuo)用來源(yuan)(yuan)(yuan)于相應的(de)(de)(de)(de)(de)物理(li)效應或化學(xue)效應，通常(chang)還伴(ban)隨著(zhu)能(neng)(neng)量(liang)的(de)(de)(de)(de)(de)轉換，因(yin)為電(dian)(dian)(dian)(dian)(dian)(dian)流在導(dao)體(ti)(ti)中(zhong)（超導(dao)體(ti)(ti)除外）流動(dong)時要消(xiao)耗(hao)能(neng)(neng)量(liang)，這個能(neng)(neng)量(liang)必(bi)須由產生(sheng)電(dian)(dian)(dian)(dian)(dian)(dian)動(dong)勢的(de)(de)(de)(de)(de)能(neng)(neng)源(yuan)(yuan)(yuan)補(bu)償。如果(guo)電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)電(dian)(dian)(dian)(dian)(dian)(dian)動(dong)勢只發(fa)生(sheng)在導(dao)體(ti)(ti)回(hui)路(lu)的(de)(de)(de)(de)(de)一部(bu)分(fen)(fen)區(qu)域(yu)中(zhong)，就稱(cheng)(cheng)這部(bu)分(fen)(fen)區(qu)域(yu)為電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)區(qu)。電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)區(qu)中(zhong)也(ye)存(cun)在著(zhu)電(dian)(dian)(dian)(dian)(dian)(dian)阻，稱(cheng)(cheng)為電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)的(de)(de)(de)(de)(de)內阻。電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)區(qu)之外部(bu)分(fen)(fen)導(dao)體(ti)(ti)回(hui)路(lu)中(zhong)所消(xiao)耗(hao)的(de)(de)(de)(de)(de)能(neng)(neng)量(liang)，直接(jie)來源(yuan)(yuan)(yuan)于導(dao)體(ti)(ti)中(zhong)的(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)磁(ci)場，但是這時電(dian)(dian)(dian)(dian)(dian)(dian)磁(ci)場的(de)(de)(de)(de)(de)能(neng)(neng)量(liang)仍(reng)然來自電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)。

在(zai)電(dian)(dian)源內部(bu)，非(fei)靜電(dian)(dian)力把正(zheng)電(dian)(dian)荷從負極(ji)板(ban)移到正(zheng)極(ji)板(ban)時要對電(dian)(dian)荷做(zuo)(zuo)功(gong)，這(zhe)個做(zuo)(zuo)功(gong)的物理過(guo)(guo)程是(shi)產生電(dian)(dian)源電(dian)(dian)動勢的本質。非(fei)靜電(dian)(dian)力所做(zuo)(zuo)的功(gong)，反映了其他形式的能量有多少變(bian)成了電(dian)(dian)能。因此在(zai)電(dian)(dian)源內部(bu)，非(fei)靜電(dian)(dian)力做(zuo)(zuo)功(gong)的過(guo)(guo)程是(shi)能量相互(hu)轉化的過(guo)(guo)程。

電(dian)(dian)源(yuan)電(dian)(dian)動勢(shi)的(de)(de)大小等(deng)于非(fei)靜(jing)電(dian)(dian)力把單位正(zheng)電(dian)(dian)荷從電(dian)(dian)源(yuan)的(de)(de)負(fu)(fu)極(ji)，經(jing)過電(dian)(dian)源(yuan)內部移到電(dian)(dian)源(yuan)正(zheng)極(ji)所作的(de)(de)功。如(ru)設W為(wei)電(dian)(dian)源(yuan)中非(fei)靜(jing)電(dian)(dian)力（電(dian)(dian)源(yuan)力）把正(zheng)電(dian)(dian)荷量(liang)q從負(fu)(fu)極(ji)經(jing)過電(dian)(dian)源(yuan)內部移送到電(dian)(dian)源(yuan)正(zheng)極(ji)所作的(de)(de)功跟被移送的(de)(de)電(dian)(dian)荷量(liang)的(de)(de)比(bi)值。

如：電(dian)(dian)(dian)動(dong)(dong)勢為6伏說(shuo)明電(dian)(dian)(dian)源把1庫正電(dian)(dian)(dian)荷(he)從負(fu)極經內電(dian)(dian)(dian)路移動(dong)(dong)到正極時非靜電(dian)(dian)(dian)力做功6焦(jiao)。有6焦(jiao)的其他其形式能(neng)轉換為電(dian)(dian)(dian)能(neng)。

擴展資料

不同(tong)(tong)電源(yuan)非靜電力的(de)來源(yuan)不同(tong)(tong)，能量轉(zhuan)換形式也(ye)不同(tong)(tong)。

化學電動勢(shi)（干電池、鈕(niu)扣電池、蓄電池等(deng)）的非靜電力是一種切割磁場(chang)而(er)產生電動勢(shi)。

與離子的(de)(de)(de)(de)溶解(jie)和沉積過程相(xiang)聯系(xi)的(de)(de)(de)(de)化(hua)學(xue)作(zuo)(zuo)用，電(dian)動勢(shi)的(de)(de)(de)(de)大小取決于化(hua)學(xue)作(zuo)(zuo)用的(de)(de)(de)(de)種類，與電(dian)源大小無(wu)關(guan)，如干電(dian)池(chi)無(wu)論1號(hao)、2號(hao)、5號(hao)電(dian)動勢(shi)都是(shi)1.5伏(fu)。產生(sheng)化(hua)學(xue)電(dian)動勢(shi)的(de)(de)(de)(de)電(dian)池(chi)稱(cheng)為(wei)化(hua)學(xue)電(dian)池(chi)或電(dian)化(hua)電(dian)池(chi)，例如：銅鋅原(yuan)電(dian)池(chi)，電(dian)解(jie)質(zhi)溶液為(wei)硫酸銅溶液。

感生(sheng)電(dian)(dian)動(dong)勢和(he)動(dong)生(sheng)電(dian)(dian)動(dong)勢（發電(dian)(dian)機）。發電(dian)(dian)機的非靜電(dian)(dian)力(li)起源于磁場對運動(dong)電(dian)(dian)荷的作用(yong)，即洛(luo)倫茲力(li)。

根據法拉第(di)電(dian)(dian)磁(ci)(ci)感(gan)(gan)應定律：只(zhi)要穿過回路(lu)的(de)(de)磁(ci)(ci)通量發生(sheng)了(le)變化，在(zai)回路(lu)中(zhong)就會有(you)感(gan)(gan)應電(dian)(dian)動勢產(chan)生(sheng)。而(er)實際上，引起磁(ci)(ci)通量變化的(de)(de)原因不外乎兩條：其一是回路(lu)相(xiang)(xiang)對于磁(ci)(ci)場(chang)(chang)有(you)運(yun)動；其二是回路(lu)在(zai)磁(ci)(ci)場(chang)(chang)中(zhong)雖無(wu)相(xiang)(xiang)對運(yun)動，但是磁(ci)(ci)場(chang)(chang)在(zai)空間的(de)(de)分布是隨時間變化的(de)(de)，將前一原因產(chan)生(sheng)的(de)(de)感(gan)(gan)應電(dian)(dian)動勢稱為動生(sheng)電(dian)(dian)動勢，而(er)后一原因產(chan)生(sheng)的(de)(de)感(gan)(gan)應電(dian)(dian)動勢稱為感(gan)(gan)生(sheng)電(dian)(dian)動勢。

電源電動(dong)勢(shi)大小測量方法

使用電壓表

電(dian)(dian)(dian)(dian)源(yuan)(yuan)的電(dian)(dian)(dian)(dian)動(dong)勢(shi)(shi)可以(yi)(yi)用電(dian)(dian)(dian)(dian)壓表測(ce)量。測(ce)量的時候(hou)，電(dian)(dian)(dian)(dian)源(yuan)(yuan)不要接(jie)到電(dian)(dian)(dian)(dian)路(lu)中(zhong)(zhong)去(qu)，用電(dian)(dian)(dian)(dian)壓表測(ce)量電(dian)(dian)(dian)(dian)源(yuan)(yuan)兩端的電(dian)(dian)(dian)(dian)壓，所得的電(dian)(dian)(dian)(dian)壓值就(jiu)可以(yi)(yi)看(kan)作等于電(dian)(dian)(dian)(dian)源(yuan)(yuan)的電(dian)(dian)(dian)(dian)動(dong)勢(shi)(shi)。如果電(dian)(dian)(dian)(dian)源(yuan)(yuan)接(jie)在(zai)電(dian)(dian)(dian)(dian)路(lu)中(zhong)(zhong)，用電(dian)(dian)(dian)(dian)壓表測(ce)得的電(dian)(dian)(dian)(dian)源(yuan)(yuan)兩端的電(dian)(dian)(dian)(dian)壓就(jiu)會(hui)小于電(dian)(dian)(dian)(dian)源(yuan)(yuan)的電(dian)(dian)(dian)(dian)動(dong)勢(shi)(shi)。這是因為電(dian)(dian)(dian)(dian)源(yuan)(yuan)有內電(dian)(dian)(dian)(dian)阻(zu)。

使用電位差計

當有(you)限(xian)電(dian)(dian)(dian)(dian)流(liu)通過時，在(zai)電(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)內阻上要(yao)產(chan)生(sheng)電(dian)(dian)(dian)(dian)位降，從而使(shi)(shi)得兩(liang)極間的(de)(de)電(dian)(dian)(dian)(dian)位差較電(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)電(dian)(dian)(dian)(dian)動勢(shi)(shi)要(yao)小(xiao)。因此，只有(you)在(zai)沒有(you)電(dian)(dian)(dian)(dian)流(liu)通過電(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)時兩(liang)電(dian)(dian)(dian)(dian)極間的(de)(de)電(dian)(dian)(dian)(dian)位差才與電(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)電(dian)(dian)(dian)(dian)動勢(shi)(shi)相等。在(zai)精確測量(liang)時，不(bu)能(neng)直接用(yong)伏特(te)計(ji)來測量(liang)一(yi)個電(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)的(de)(de)電(dian)(dian)(dian)(dian)動勢(shi)(shi)，就是(shi)因為使(shi)(shi)用(yong)伏特(te)計(ji)時必須(xu)使(shi)(shi)有(you)限(xian)的(de)(de)電(dian)(dian)(dian)(dian)流(liu)通過回(hui)路才能(neng)驅(qu)動指針旋轉，所得結果必然不(bu)是(shi)電(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)的(de)(de)電(dian)(dian)(dian)(dian)動勢(shi)(shi)，而只是(shi)電(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)兩(liang)極間的(de)(de)路端電(dian)(dian)(dian)(dian)壓。

一般采(cai)用(yong)(yong)補償法測(ce)(ce)電(dian)(dian)池的(de)(de)(de)電(dian)(dian)動勢，常(chang)用(yong)(yong)的(de)(de)(de)儀器(qi)為電(dian)(dian)位(wei)差(cha)計。電(dian)(dian)位(wei)差(cha)計是按(an)照對消法測(ce)(ce)量原理而設計的(de)(de)(de)一種平衡式電(dian)(dian)壓測(ce)(ce)量儀器(qi)。它與標準電(dian)(dian)池、檢流計等(deng)相(xiang)配合，成為電(dian)(dian)壓測(ce)(ce)量的(de)(de)(de)基本儀器(qi)。