一、電壓表怎么看測量對象
判斷電(dian)壓(ya)(ya)表(biao)測量的(de)(de)是電(dian)路(lu)中(zhong)(zhong)哪(na)一部(bu)分的(de)(de)電(dian)壓(ya)(ya),這類題目在(zai)練習和試(shi)題中(zhong)(zhong)頻頻出現,由于電(dian)壓(ya)(ya)表(biao)與用電(dian)器(qi)并(bing)聯(lian),在(zai)串聯(lian)電(dian)路(lu)中(zhong)(zhong),不論(lun)是實物電(dian)路(lu)還(huan)是形式有變化的(de)(de)電(dian)路(lu)圖中(zhong)(zhong),學(xue)生往(wang)往(wang)不能快(kuai)速準確地判斷電(dian)壓(ya)(ya)表(biao)究竟測量的(de)(de)是哪(na)一部(bu)分的(de)(de)電(dian)壓(ya)(ya),基于上述(shu)原因,給出以(yi)下(xia)方法:
1、短路法
電壓表去掉,假設(she)用導(dao)線接(jie)該位置(zhi),若(ruo)此時某些用電器或電源(yuan)被短路,則這些用電器或電源(yuan)即為該電壓(ya)表測量的對象。
2、去源法
“去掉”電(dian)源(用手捂住(zhu)電(dian)源),再看(kan)電(dian)壓(ya)表與(yu)哪部分構成閉(bi)合(he)回路(lu),那么電(dian)壓(ya)表測的就是(shi)那部分電(dian)路(lu)的電(dian)壓(ya)。
3、滑線法
電(dian)壓表兩(liang)端沿著連接的導線滑動(dong)到用電(dian)器(qi)或(huo)電(dian)源(yuan)兩(liang)端。(能跨過(guo)元(yuan)件:開關、電(dian)流表。不能跨過(guo)元(yuan)件:電(dian)源(yuan)、用電(dian)器(qi)、電(dian)壓表)。
4、特殊說明
(1)電(dian)壓(ya)表接(jie)在電(dian)路中相(xiang)當于該處開路。
(2)電流表(biao)接在電路中(zhong)相當于一根導線(xian)。
(3)電(dian)(dian)(dian)壓表與用電(dian)(dian)(dian)器串聯拖后接在電(dian)(dian)(dian)源兩端,電(dian)(dian)(dian)壓表測(ce)量的是電(dian)(dian)(dian)源電(dian)(dian)(dian)壓。
二、電壓表測量對象短路會怎么樣
被(bei)測試的(de)用(yong)電(dian)(dian)(dian)器短(duan)路(lu)(lu)(lu)的(de)時候(hou),電(dian)(dian)(dian)壓(ya)表顯示為零,被(bei)測試的(de)用(yong)電(dian)(dian)(dian)器斷(duan)(duan)路(lu)(lu)(lu)的(de)時候(hou),通常很多(duo)人(ren)會認為被(bei)測試是開路(lu)(lu)(lu)電(dian)(dian)(dian)壓(ya)。實(shi)際并不準確,只有輸(shu)入電(dian)(dian)(dian)壓(ya)與(yu)被(bei)測試的(de)用(yong)電(dian)(dian)(dian)器直接相連的(de)情況下(xia),斷(duan)(duan)路(lu)(lu)(lu)之(zhi)后,電(dian)(dian)(dian)壓(ya)表測試出(chu)來(lai)才(cai)是開路(lu)(lu)(lu)電(dian)(dian)(dian)壓(ya)。但是如果輸(shu)入電(dian)(dian)(dian)壓(ya)與(yu)被(bei)測試的(de)用(yong)電(dian)(dian)(dian)器之(zhi)間有其他感容(rong)(rong)電(dian)(dian)(dian)子(zi)元(yuan)件的(de)話(hua),受到感容(rong)(rong)電(dian)(dian)(dian)子(zi)元(yuan)件的(de)影響,測試出(chu)來(lai)的(de)實(shi)際是頻率電(dian)(dian)(dian)壓(ya)。