電(dian)阻器(qi)在電(dian)路中起(qi)什么作用呢？

將電(dian)(dian)(dian)(dian)路(lu)中的(de)開關(guan)換(huan)為(wei)1個470歐(ou)姆的(de)電(dian)(dian)(dian)(dian)位(wei)器(qi)(qi)。旋(xuan)轉(zhuan)電(dian)(dian)(dian)(dian)位(wei)器(qi)(qi)的(de)轉(zhuan)柄，小燈泡的(de)亮度要(yao)隨(sui)著電(dian)(dian)(dian)(dian)阻(zu)值的(de)大小而改變。電(dian)(dian)(dian)(dian)阻(zu)值越大，小燈泡越暗。這說(shuo)明電(dian)(dian)(dian)(dian)阻(zu)器(qi)(qi)在(zai)電(dian)(dian)(dian)(dian)路(lu)中可以控制電(dian)(dian)(dian)(dian)流的(de)強(qiang)弱。

電容器在電路中有什么(me)作用(yong)呢(ni)？

用電(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)(qi)代(dai)替(ti)開關。接通(tong)(tong)(tong)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)時，我們看到小燈泡(pao)(pao)閃亮一下后就不再亮了(le)。這是(shi)因為(wei)電(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)(qi)在(zai)充電(dian)(dian)(dian)(dian)(dian)的(de)瞬間(jian)(jian)，電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)中有(you)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)。而(er)充電(dian)(dian)(dian)(dian)(dian)過(guo)程很快結束了(le)，電(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)(qi)充滿(man)電(dian)(dian)(dian)(dian)(dian)荷(he)后，電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)消失了(le)。電(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)(qi)容(rong)量越(yue)小，充電(dian)(dian)(dian)(dian)(dian)所用時間(jian)(jian)越(yue)短暫(zan)，可見直流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)是(shi)不能通(tong)(tong)(tong)過(guo)電(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)(qi)的(de)。若(ruo)將電(dian)(dian)(dian)(dian)(dian)源(yuan)改為(wei)交(jiao)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)源(yuan)，小燈泡(pao)(pao)將持續發(fa)光，若(ruo)交(jiao)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)頻率(lv)可以(yi)(yi)變化，那么(me)在(zai)相同的(de)電(dian)(dian)(dian)(dian)(dian)壓下，高頻率(lv)交(jiao)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)較低頻率(lv)交(jiao)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)更易于通(tong)(tong)(tong)過(guo)同一個電(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)(qi)而(er)使小燈泡(pao)(pao)更亮些(xie)。這些(xie)實(shi)驗可以(yi)(yi)說明電(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)(qi)在(zai)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)中，可以(yi)(yi)起“隔直流(liu)(liu)，通(tong)(tong)(tong)交(jiao)流(liu)(liu)”，“通(tong)(tong)(tong)高頻、阻低頻”的(de)作用。

晶體二極管在電路中(zhong)有(you)什(shen)么作用(yong)呢(ni)？

我們將(jiang)晶體二(er)(er)極(ji)管(guan)(guan)(guan)(guan)接在(zai)電(dian)路(lu)中的(de)(de)開關位置上，燈泡發光(guang)，說明這時(shi)二(er)(er)極(ji)管(guan)(guan)(guan)(guan)導(dao)通，二(er)(er)極(ji)管(guan)(guan)(guan)(guan)的(de)(de)電(dian)阻(zu)（稱為(wei)(wei)正(zheng)向電(dian)阻(zu)）很小。若將(jiang)二(er)(er)極(ji)管(guan)(guan)(guan)(guan)兩極(ji)引腳對調，這時(shi)小燈泡不亮了。這時(shi)二(er)(er)極(ji)管(guan)(guan)(guan)(guan)的(de)(de)電(dian)阻(zu)（稱為(wei)(wei)反向電(dian)阻(zu)）很大(da)，電(dian)路(lu)中幾乎沒(mei)有電(dian)流(liu)。這個(ge)現象說明二(er)(er)極(ji)管(guan)(guan)(guan)(guan)有單(dan)向導(dao)電(dian)的(de)(de)特性。利(li)用(yong)二(er)(er)極(ji)管(guan)(guan)(guan)(guan)的(de)(de)這個(ge)特性，可使用(yong)二(er)(er)極(ji)管(guan)(guan)(guan)(guan)進行檢波和(he)整流(liu)。