電(dian)阻器(qi)在(zai)電(dian)路中起(qi)什么作用呢？

將電(dian)(dian)(dian)路中的開關換(huan)為1個470歐姆的電(dian)(dian)(dian)位器(qi)。旋轉(zhuan)電(dian)(dian)(dian)位器(qi)的轉(zhuan)柄，小燈(deng)泡的亮度要隨(sui)著電(dian)(dian)(dian)阻(zu)值(zhi)的大(da)小而改變。電(dian)(dian)(dian)阻(zu)值(zhi)越大(da)，小燈(deng)泡越暗。這說明(ming)電(dian)(dian)(dian)阻(zu)器(qi)在(zai)電(dian)(dian)(dian)路中可以控制電(dian)(dian)(dian)流的強弱。

電容(rong)器在電路(lu)中有什么作(zuo)用呢？

用(yong)電(dian)(dian)(dian)(dian)容(rong)(rong)器(qi)代(dai)替開(kai)關。接(jie)通(tong)電(dian)(dian)(dian)(dian)路(lu)時，我(wo)們看到小燈泡閃(shan)亮(liang)一下后就不再(zai)亮(liang)了(le)。這(zhe)是因為電(dian)(dian)(dian)(dian)容(rong)(rong)器(qi)在充電(dian)(dian)(dian)(dian)的(de)瞬(shun)間，電(dian)(dian)(dian)(dian)路(lu)中有電(dian)(dian)(dian)(dian)流(liu)。而(er)充電(dian)(dian)(dian)(dian)過程很快結束了(le)，電(dian)(dian)(dian)(dian)容(rong)(rong)器(qi)充滿電(dian)(dian)(dian)(dian)荷(he)后，電(dian)(dian)(dian)(dian)流(liu)消失了(le)。電(dian)(dian)(dian)(dian)容(rong)(rong)器(qi)容(rong)(rong)量越小，充電(dian)(dian)(dian)(dian)所用(yong)時間越短暫，可(ke)見直流(liu)電(dian)(dian)(dian)(dian)是不能通(tong)過電(dian)(dian)(dian)(dian)容(rong)(rong)器(qi)的(de)。若(ruo)將(jiang)電(dian)(dian)(dian)(dian)源改為交(jiao)(jiao)(jiao)流(liu)電(dian)(dian)(dian)(dian)源，小燈泡將(jiang)持續發光，若(ruo)交(jiao)(jiao)(jiao)流(liu)電(dian)(dian)(dian)(dian)頻(pin)(pin)率可(ke)以(yi)變(bian)化(hua)，那么在相同的(de)電(dian)(dian)(dian)(dian)壓下，高頻(pin)(pin)率交(jiao)(jiao)(jiao)流(liu)電(dian)(dian)(dian)(dian)較低頻(pin)(pin)率交(jiao)(jiao)(jiao)流(liu)電(dian)(dian)(dian)(dian)更易于通(tong)過同一個電(dian)(dian)(dian)(dian)容(rong)(rong)器(qi)而(er)使小燈泡更亮(liang)些。這(zhe)些實(shi)驗可(ke)以(yi)說明電(dian)(dian)(dian)(dian)容(rong)(rong)器(qi)在電(dian)(dian)(dian)(dian)路(lu)中，可(ke)以(yi)起“隔(ge)直流(liu)，通(tong)交(jiao)(jiao)(jiao)流(liu)”，“通(tong)高頻(pin)(pin)、阻低頻(pin)(pin)”的(de)作用(yong)。

晶體二極管(guan)在電(dian)路中(zhong)有(you)什么作用呢？

我們(men)將晶體(ti)二(er)(er)極(ji)管(guan)(guan)(guan)接在(zai)電(dian)(dian)(dian)路中的(de)開(kai)關(guan)位置(zhi)上(shang)，燈(deng)泡發(fa)光，說明(ming)這時二(er)(er)極(ji)管(guan)(guan)(guan)導通，二(er)(er)極(ji)管(guan)(guan)(guan)的(de)電(dian)(dian)(dian)阻(zu)（稱(cheng)為(wei)正(zheng)向(xiang)(xiang)電(dian)(dian)(dian)阻(zu)）很小。若將二(er)(er)極(ji)管(guan)(guan)(guan)兩極(ji)引腳對調，這時小燈(deng)泡不亮了。這時二(er)(er)極(ji)管(guan)(guan)(guan)的(de)電(dian)(dian)(dian)阻(zu)（稱(cheng)為(wei)反向(xiang)(xiang)電(dian)(dian)(dian)阻(zu)）很大，電(dian)(dian)(dian)路中幾(ji)乎沒有(you)電(dian)(dian)(dian)流(liu)。這個(ge)現(xian)象說明(ming)二(er)(er)極(ji)管(guan)(guan)(guan)有(you)單(dan)向(xiang)(xiang)導電(dian)(dian)(dian)的(de)特性(xing)。利用(yong)二(er)(er)極(ji)管(guan)(guan)(guan)的(de)這個(ge)特性(xing)，可使用(yong)二(er)(er)極(ji)管(guan)(guan)(guan)進行(xing)檢波和整流(liu)。