【正文】 ?? ???? 222 3050)( ??L? 40 ????L 已知 ? ?V 001sin2 tu S ? ， 試 求圖 中的電壓 u 。 利用分壓公式得 V45202j44 4j022j22j2j112j22j2??????????????????? mU ? ?V4510 0s in2 ??? tu 求圖 所示電路的各支路電流。 圖 習(xí)題 電路圖 習(xí)題 相量圖 解 Cmm ???????? ?? UCI ?， A)4( ti ? ???? ?? IRU ， V)4(sin20R tu ? mLm ????? ?? ILU ? ， V)904(sin20L ??? tu V3 6 . 8 72551j20j5j 2 020CmLmRmSm ??????????? ???? UUUU V)(s in25S ??? tu 利用支路電流法 求圖 中 各 支路電流。 圖 習(xí)題 電路圖 解 列 KCL 、 KVL 方程 為 ? ?? ?????????????????????????????8j4j4j40124j4802121IIIIIII 整理得 ? ? ? ?? ????????????????????2jj103j1j32121IIII j3 2j11 ????I j3 9j12 ????I 7j21 ????????? ??? III 用節(jié)點(diǎn)法求圖 中的 電壓 ?U 。 圖 習(xí)題 電路圖 解 0j1 9032j106 ?? ?????? ?????? UUU 整理得： ? ? ? ? 0j31j12261j12 ??????? ??????????? ??? ??? UUU 求得 V4523j33 ??????U 已知 ? ?A30 5sin2S1 ??? ti ， ? ?A ti ? ， 用疊加原理求圖 中的電流 i 。 圖 習(xí)題 電路圖 解 電 流 源單獨(dú)作用時(shí) ? ? 5j2j1 ????? ?????U 電壓源單獨(dú)作用 時(shí) V5032j5j 5j2 ???????U o21 ?????? ??? UUU 已知 ? ?V 4sin28S1 tu ? ， ? ?V 4sin23S2 tu ? ，試 用 戴維南定理求圖 中的 電流 i 。 圖 習(xí)題 電路圖 解 （ 1）開路電壓 OC?U 的計(jì)算 V4524j44 j48OC ???????U 等效電阻 SZ 的計(jì)算 ?????? 22j4j4 4j4SZ 短路電流 SC?I 計(jì)算 A4522j2j4 j4j2j4j 2)(j44 8SC ???????????I 其戴維南等效電路和諾頓等效電路如圖 a 和 b 所示 （ a） 戴維南等效電路 （ b） 諾頓等效電路 在圖 所示 電路中， 已知 ? ?Vcos24S tu ?? ，求 i 、 u 及電壓源提供的有功功率。燈管電壓為 V75 。 解 ??? PI 030 ???? UIP? 求 圖 所示 電路中 網(wǎng)絡(luò) N 的 阻抗、 有功功率、無功功率、功率因數(shù)和視在功率。求：（ 1）并聯(lián)電容前通過負(fù)載的電流 ?LI 及負(fù)載阻抗 Z ；（ 2）為了提高功率因數(shù)，在感性負(fù)載上并聯(lián)電容，如虛線所示，欲把功率因數(shù)提高到 1應(yīng)并聯(lián)多大電容及并上電容后線路上的電流 I 。求 諧振頻 率 、 品質(zhì)因數(shù) 、 諧振時(shí)的電流 和 電阻兩端、電感及電容兩端的電壓。 求 C 值。 圖 習(xí)題 電路圖 解 r a d / s2411110 ???? LC? A03 oSR ??? ?? II A09159012 0310j oSL ?????? ?????? ?? LIRI ? A0915031090412Cj oSC ????????????? ?? IRI ? 故 ? ?A 2sin23R ti ? A )90 (2s in215L ??? ti A )90 (2s in215C ??? ti 圖 諧振電路中， V) 1000sin(220S tu ? ,電流表讀數(shù)是 A20 ，電壓表讀數(shù)是 V200 ，求 CLR 、 的參數(shù)。 又因?yàn)? CL 00 1?? ? 所以 μF100F101010 11 42620 ????? ??LC ?。求 R 和 L 。 圖 所示對稱電路，已知 ? ???? 2j2Z ， V0220A ????U ，求每相負(fù)載的相電流及線電流。 A相負(fù)載的相電流 2j2 30380ABAB ????? ??????ZUI B 相負(fù)載的相電流 A13 4BC ?????I C 相負(fù)載的相電流 A1 34CA ????I A相 的線電流 3 2303 ABA ???????? ?? II B 相 的線電流 A1 6 3 2B ?????I C 相 的線電流 2C ????I 在 圖 所示 對稱三相電路中，已知電源 正 相序且 V0380 oAB ???U ，每相阻抗 ??? )4j3(Z 。 圖 3. 28 習(xí)題 電路圖 解 由于電源對稱且 正 相序 ，由此可得 A相電壓為 V30220303 ooABA ?????? ?? UU 4j3 30220 oAAA ???? ???????ZUI ooAoAB ???????? ??? III ooAC ????? ?? II 在圖 所示 對稱三相電路中，已知 V0380AB ????U ， ???? 60101Z ，? ???? 3j42Z ，求電流表的讀數(shù)。 to implement , do not want to, dare not, not with disciplinary ruler to supervision。 not to have conquered, but to have fought well. 2, the plain is the background of life. Live a plain life, give up on themselves is not a coward, but the wise answers。 not unrewarding perfunctorily, but calm attitude of life of unrestrained selfconfidence. Plain living, there is no noise noisy, no earthly troubles, more did not fill in the discontent of desire, some just a calm, a calm. 3, memory of heart will not good things to erase the, life is a When no movie, pain is a beginning, the struggle is a kind of process, death is a kind of ending. Give up this giving up is the helpless, do not give up the abandoned, do not give up this giving up is ignorance, do not give up should not give up is persistent. 4, a thing figured is heaven, think impassability is hell. Since the living, to live better. Sometimes we because of too narrowminded, too care around the chores and penny wise and pound foolish, not worth the candle. Some things to attract trouble and worry, pletely depends on how we look at and deal with it. Don39。t get into a blind alley, don39。t be narrowminded. Poke to care, is a kind of openminded, a free and easy. 5, I am not afraid of others behind me a knife, I afraid to look back and see stab me, is my intention to treat people。m afraid he turned to it as a joke to tell don39。 and when we are in a negative state of mind, you will find many depressed things。 loss of sink, Eritrea pany. When you are in adversity, may wish to change a point of view to think everything over to the good Think, because good mentality decided the fate of the! 7, people are tired, rest。 you pain, no one can understand. Then you only tears to smile. 8, each people have youth, Each youth are a story, the life of the world never gets easier, I want what, wish the world all know, as has been the same。s mouth, because words will reduce its importance。t envy who. Like a person is a kind of feeling, not like a person is true. The truth is easy to explain, I feel Is unspeakable. The best travel life is that you in a strange place found a long lost touched. 11, happy life not in the bustling in, and in the peace of mind。am, like a movie, learn to appreciate, learn to be grateful, learn tolerance, and goodness, helping others. Instead of accusing the society, as into one。t envy him A sum of, don39。t let everyone like you, so also do not want to do. Life is too short to go crazy to love to go to waste, to chase the dream to regret. 15, when temper, a blessing to go. A wounding elegant people, the key is to control their own emotions. With the mouth is the most stupid behavior. A control negative emotions than a can take a city more powerful water flow slow, language is expensive. People spent two years of time to learn to speak, but to spend a few years time to shut up. That is a kind of ability, that is a kind of wisdom. 16, life is not perfect, sometimes, growth is n