一、電壓表怎么看測量對象

判斷(duan)電(dian)(dian)(dian)(dian)(dian)壓(ya)表測量的(de)(de)是電(dian)(dian)(dian)(dian)(dian)路中(zhong)哪一(yi)部(bu)分(fen)(fen)的(de)(de)電(dian)(dian)(dian)(dian)(dian)壓(ya)，這類(lei)題目在(zai)練習和試題中(zhong)頻(pin)頻(pin)出現(xian)，由于(yu)電(dian)(dian)(dian)(dian)(dian)壓(ya)表與用電(dian)(dian)(dian)(dian)(dian)器并聯，在(zai)串聯電(dian)(dian)(dian)(dian)(dian)路中(zhong)，不論是實(shi)物(wu)電(dian)(dian)(dian)(dian)(dian)路還是形式有(you)變化的(de)(de)電(dian)(dian)(dian)(dian)(dian)路圖中(zhong)，學生往往不能(neng)快速準確地判斷(duan)電(dian)(dian)(dian)(dian)(dian)壓(ya)表究竟測量的(de)(de)是哪一(yi)部(bu)分(fen)(fen)的(de)(de)電(dian)(dian)(dian)(dian)(dian)壓(ya)，基于(yu)上(shang)述原因，給出以下方(fang)法：

1、短路法

電壓表去掉，假設用導線接(jie)該位(wei)置，若此時(shi)某些用電(dian)器或電(dian)源被短路，則這些用電(dian)器或電(dian)源即為該電(dian)壓表測量(liang)的對象。

2、去源法

“去掉”電(dian)(dian)源（用手捂住(zhu)電(dian)(dian)源），再看電(dian)(dian)壓(ya)表與哪部分構成閉合回路(lu)，那(nei)么電(dian)(dian)壓(ya)表測的就(jiu)是那(nei)部分電(dian)(dian)路(lu)的電(dian)(dian)壓(ya)。

3、滑線法

電(dian)(dian)(dian)(dian)壓(ya)表兩端沿著連(lian)接(jie)的導線滑動到用(yong)電(dian)(dian)(dian)(dian)器(qi)或電(dian)(dian)(dian)(dian)源兩端。（能跨(kua)過元件：開(kai)關、電(dian)(dian)(dian)(dian)流表。不能跨(kua)過元件：電(dian)(dian)(dian)(dian)源、用(yong)電(dian)(dian)(dian)(dian)器(qi)、電(dian)(dian)(dian)(dian)壓(ya)表）。

4、特殊說明

（1）電壓表接在電路中相當于(yu)該處開路。

（2）電(dian)流表接在電(dian)路中相當于(yu)一根(gen)導(dao)線。

（3）電(dian)(dian)壓表與用(yong)電(dian)(dian)器串聯拖(tuo)后(hou)接在電(dian)(dian)源(yuan)兩端，電(dian)(dian)壓表測量的(de)是電(dian)(dian)源(yuan)電(dian)(dian)壓。

二、電壓表測量對象短路會怎么樣

被(bei)測試(shi)的用(yong)(yong)電(dian)器(qi)短(duan)路的時(shi)候(hou)，電(dian)壓(ya)表(biao)顯示為(wei)零，被(bei)測試(shi)的用(yong)(yong)電(dian)器(qi)斷路的時(shi)候(hou)，通(tong)常很多人會認為(wei)被(bei)測試(shi)是開(kai)路電(dian)壓(ya)。實際并不準確(que)，只有輸入(ru)(ru)電(dian)壓(ya)與(yu)被(bei)測試(shi)的用(yong)(yong)電(dian)器(qi)直接相連的情況(kuang)下，斷路之(zhi)后，電(dian)壓(ya)表(biao)測試(shi)出(chu)來才(cai)是開(kai)路電(dian)壓(ya)。但是如果輸入(ru)(ru)電(dian)壓(ya)與(yu)被(bei)測試(shi)的用(yong)(yong)電(dian)器(qi)之(zhi)間有其他感容(rong)電(dian)子元(yuan)件的話，受到感容(rong)電(dian)子元(yuan)件的影響，測試(shi)出(chu)來的實際是頻率電(dian)壓(ya)。