電阻(zu)器在電路中(zhong)起(qi)什么作用呢？

將電(dian)(dian)路(lu)中(zhong)(zhong)的開關換為(wei)1個(ge)470歐(ou)姆(mu)的電(dian)(dian)位器。旋轉電(dian)(dian)位器的轉柄，小燈(deng)泡的亮度(du)要隨著電(dian)(dian)阻(zu)值的大小而改變(bian)。電(dian)(dian)阻(zu)值越(yue)大，小燈(deng)泡越(yue)暗。這說明(ming)電(dian)(dian)阻(zu)器在電(dian)(dian)路(lu)中(zhong)(zhong)可以控制電(dian)(dian)流(liu)的強弱。

電容器在電路(lu)中有什(shen)么(me)作用呢？

用電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)代替開關(guan)。接通(tong)(tong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)時，我們看到小燈(deng)泡(pao)閃(shan)亮(liang)(liang)一(yi)下(xia)后就不再亮(liang)(liang)了。這是因為電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)在充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)瞬間(jian)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)中有(you)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)。而充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)過程很快結束了，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)充(chong)(chong)滿電(dian)(dian)(dian)(dian)(dian)(dian)(dian)荷后，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)消失了。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)容(rong)量越(yue)小，充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)所用時間(jian)越(yue)短(duan)暫(zan)，可見直流(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)是不能通(tong)(tong)過電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)的(de)(de)(de)。若(ruo)將(jiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源改為交(jiao)(jiao)流(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源，小燈(deng)泡(pao)將(jiang)持續發(fa)光，若(ruo)交(jiao)(jiao)流(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)頻(pin)率可以變化，那(nei)么在相(xiang)同(tong)的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)下(xia)，高頻(pin)率交(jiao)(jiao)流(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)較低頻(pin)率交(jiao)(jiao)流(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)更易于通(tong)(tong)過同(tong)一(yi)個(ge)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)而使小燈(deng)泡(pao)更亮(liang)(liang)些。這些實驗可以說(shuo)明電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)在電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)中，可以起“隔(ge)直流(liu)，通(tong)(tong)交(jiao)(jiao)流(liu)”，“通(tong)(tong)高頻(pin)、阻(zu)低頻(pin)”的(de)(de)(de)作用。

晶體二(er)極管在電路中有什(shen)么作用呢(ni)？

我們將晶體二(er)(er)(er)極(ji)(ji)管接在(zai)電(dian)(dian)路(lu)中(zhong)的開(kai)關位置(zhi)上，燈(deng)泡(pao)發(fa)光，說明這(zhe)時二(er)(er)(er)極(ji)(ji)管導通，二(er)(er)(er)極(ji)(ji)管的電(dian)(dian)阻(zu)（稱為正向電(dian)(dian)阻(zu)）很小。若將二(er)(er)(er)極(ji)(ji)管兩極(ji)(ji)引腳對(dui)調，這(zhe)時小燈(deng)泡(pao)不亮了。這(zhe)時二(er)(er)(er)極(ji)(ji)管的電(dian)(dian)阻(zu)（稱為反向電(dian)(dian)阻(zu)）很大，電(dian)(dian)路(lu)中(zhong)幾乎(hu)沒有(you)(you)電(dian)(dian)流。這(zhe)個(ge)現象說明二(er)(er)(er)極(ji)(ji)管有(you)(you)單向導電(dian)(dian)的特性。利用二(er)(er)(er)極(ji)(ji)管的這(zhe)個(ge)特性，可使用二(er)(er)(er)極(ji)(ji)管進(jin)行檢波(bo)和整流。