電容器原理
在(zai)生產及生活實(shi)踐(jian)中,科學家(jia)們發現,凡是被絕緣隔開的(de)兩個導(dao)體之間加(jia)以電(dian)(dian)壓時,則接在(zai)高電(dian)(dian)位的(de)導(dao)體就能(neng)容(rong)納正電(dian)(dian)荷,接在(zai)低電(dian)(dian)位的(de)導(dao)體能(neng)容(rong)納負電(dian)(dian)荷。由此可見,上述(shu)導(dao)體和(he)絕緣所(suo)構成的(de)整體有容(rong)納電(dian)(dian)荷的(de)能(neng)力,這種能(neng)力叫(jiao)做電(dian)(dian)容(rong)。而這個整體就叫(jiao)做電(dian)(dian)容(rong)器。
電容計算公式
實踐證明:任一(yi)電(dian)容(rong)(rong)(rong)器容(rong)(rong)(rong)納(na)(na)電(dian)荷的(de)(de)情(qing)況(kuang)和一(yi)個籃球容(rong)(rong)(rong)納(na)(na)氣體的(de)(de)情(qing)況(kuang)類似(si)。籃球大(da)氣的(de)(de)氣壓越大(da),則容(rong)(rong)(rong)納(na)(na)的(de)(de)氣體越多(duo)(duo);電(dian)容(rong)(rong)(rong)器所(suo)加的(de)(de)電(dian)壓越大(da),則容(rong)(rong)(rong)納(na)(na)的(de)(de)電(dian)荷也越多(duo)(duo)。這樣一(yi)來,要(yao)衡量它容(rong)(rong)(rong)納(na)(na)電(dian)荷的(de)(de)本領,就必須(xu)在(zai)同一(yi)電(dian)壓下(xia)來衡量,單位(wei)電(dian)壓下(xia)所(suo)能(neng)容(rong)(rong)(rong)納(na)(na)電(dian)荷的(de)(de)多(duo)(duo)少叫電(dian)容(rong)(rong)(rong),用C表示,單位(wei)法(fa)拉:
上公式中q是電容(rong)(rong)器在外加電壓U時所容(rong)(rong)納(na)的電荷量。
實(shi)際(ji)使用中常見的(de)(de)(de)(de)電(dian)(dian)(dian)容(rong)(rong)器(qi)的(de)(de)(de)(de)容(rong)(rong)量(liang)在其被制造出來時(shi)都有表(biao)明,電(dian)(dian)(dian)容(rong)(rong)器(qi)元件(jian)表(biao)面的(de)(de)(de)(de)數字或(huo)者色(se)環就包含(han)了容(rong)(rong)量(liang)信息。1法(fa)拉等于1庫侖每(mei)伏(fu)特,即(ji)電(dian)(dian)(dian)容(rong)(rong)為(wei)1法(fa)拉的(de)(de)(de)(de)電(dian)(dian)(dian)容(rong)(rong)器(qi),在正常操(cao)作(zuo)范圍內,每(mei)增(zeng)加1伏(fu)特的(de)(de)(de)(de)電(dian)(dian)(dian)勢差(cha)可以多儲存1庫侖的(de)(de)(de)(de)電(dian)(dian)(dian)荷。
電容單位換算
電容(rong)的容(rong)量單位是(shi)(shi)法拉(用(yong)字母(mu)F表(biao)示),但是(shi)(shi)在實(shi)際應(ying)用(yong)上,法拉這一單位太大了。往往使用(yong)最多的是(shi)(shi)微法(uF)或(huo)皮法(PF)。
1F=1000,000微(wei)(wei)法=106微(wei)(wei)法(uF)
1uF=1000,000皮法(fa)=106皮法(fa)(PF)
電(dian)(dian)容(rong)的(de)大小與電(dian)(dian)容(rong)器的(de)幾何尺(chi)寸和介質的(de)性質有關。除了(le)電(dian)(dian)容(rong)器有電(dian)(dian)容(rong)外,在實際中,電(dian)(dian)氣(qi)設備(bei)、線(xian)(xian)路與部件都具有自然形成的(de)電(dian)(dian)容(rong)。如較長的(de)輸電(dian)(dian)線(xian)(xian)之(zhi)間(jian),較長的(de)電(dian)(dian)纜都具有電(dian)(dian)容(rong)。