两个定值电阻R1和R2,它们并联后的总电阻为R 有两个定值电阻R1和R2，有R1：R2=1：2．若把它们串联...
\u6709\u4e24\u4e2a\u5b9a\u503c\u7535\u963bR1\u3001R2\uff0c\u5b83\u4eec\u7535\u6d41\u968f\u7535\u538b\u53d8\u5316\u56fe\u8c61\u5982\u56fe\u6240\u793a\u5982\u679c\u4e32\u8054\u540e\u603b\u7535\u963b\u4e3aR\u4e32\uff0c\u5e76\u8054\u540e\u603b\u7535\u963b\u4e3aR\u5e76\uff0c\u4e0b\u5217\u6839\u636e\u4e32\u8054\u7535\u8def\u7684\u7535\u963b\u7279\u70b9\u77e5\uff0cR\u4e32\u6bd4\u6bcf\u4e00\u4e2a\u4e32\u8054\u7684\u5206\u7535\u963b\u90fd\u8981\u5927\uff0c\u6839\u636e\u5e76\u8054\u7535\u8def\u4e2d\u7535\u963b\u7684\u7279\u70b9\u53ef\u77e5\uff0cR\u5e76\u6bd4\u6bcf\u4e00\u4e2a\u5e76\u8054\u7535\u8def\u7684\u5206\u7535\u963b\u90fd\u8981\u5c0f\uff0e\u5728\u8fd9\u56db\u4e2a\u7535\u963b\u503c\u4e2d\uff0cR\u4e32\u6700\u5927\uff0cR\u5e76\u6700\u5c0f\uff0c\u6240\u4ee5\uff0c\u5f53\u5b83\u4eec\u4e24\u7aef\u52a0\u76f8\u540c\u7684\u7535\u538b\u65f6\uff0c\u901a\u8fc7R\u4e32\u7684\u7535\u6d41\u6700\u5c0f\uff0c\u6545\u5b83\u7684I-U\u56fe\u7ebf\u5728III\u533a\uff1b\u901a\u8fc7R\u5e76\u7684\u7535\u6d41\u6700\u5927\uff0c\u6545\u5b83\u7684I-U\u56fe\u7ebf\u5728I\u533a\uff0e\u7efc\u4e0a\u5206\u6790\uff0c\u6545\u9009D\uff0e
\u5df2\u77e5R1R2=12\u6240\u4ee5R2=2R1\u4e24\u7535\u963b\u4e32\u8054\u540e\u7684\u603b\u7535\u963b\u4e3aR\u4e32=R1+R2=3R1\u4e24\u7535\u963b\u5e76\u8054\u540e\u7684\u603b\u7535\u963b\u4e3aR\u5e76=R1R2R1+R2=23R1\u4e24\u7535\u963b\u4e32\u8054\u540e\u7684\u603b\u529f\u7387\u4e3aP=U2R\u4e32=U23R1\u4e24\u7535\u963b\u5e76\u8054\u540e\u7684\u603b\u529f\u7387\u4e3aP\u2032=U2R\u5e76=U223R1\u5df2\u77e5\u7535\u6e90\u7535\u538b\u4e00\u5b9a\uff0c\u6240\u4ee5P\u00d73R1=P\u2032\u00d723R1PP\u2032=23R13R1=29\u6545\u9009B
R总=R1R2/R1+R2=R2/(1+R2/R1),R1变大，R2/R1变小，(1+R2/R1)就变小，所以R总变大。是增大的 设R2不变 恒为a R1为X 并联电阻R=ax/(a+x)
化简得 R=a-a^2/(a+x) 因为a>0 x>0 在此区间内为递增函数 所以R随x增大而增大
不管串联还是并联，一个增大另一个也增大（串联R=R1+R2,并联1/R=1/R1+1/R2)。希望对你有所帮助！
任何电路，当任一个分电阻增大时，电路的总电阻都会增大。
1／R＝1/r① 1/r② . r①增大，则1/r①减小，1/R减小，最终R增大。
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绛旓細骞惰仈锛孯1,R2鐢靛帇鍊肩浉绛夛紝I1=6/4=1.5A锛孖2=I-I1=0.5A,R2=U/I2=12惟
绛旓細璁剧數婧愮數鍘嬩负E P1 = E * E / (R1 + R2)P2 = E * E / (R1*R2/(R1+R2))鍗虫瘮杈冨垎姣嶇殑澶у皬鍗冲彲 R1+R2 - R1*R2/(R1+R2)=( (R1+R2)*(R1+R2) - R1*R2 )/(R1+R2)=( R1*R1 +R1*R2 +R2*R2 )/(R1+R2)>0 鎵浠1<P2 鎴栬呬綘杩欐牱鎯 鐩稿悓鐨鐢甸樆骞惰仈鐨勮偗瀹氭瘮涓茶仈鐨勭數闃诲皬...
绛旓細涓や釜鐏场骞惰仈璧锋潵锛屽垯瀹冧滑鐨勭數鍘嬬浉绛夛紝鏈澶х數鍘嬪垎鍒负4*1=4鍜1*2=2锛屾墍浠ュ畠浠厑璁搁氳繃鐨勬渶澶х數鍘嬩负2V 锛2V鐨勭數鍘嬩笅瀹氬肩數闃籖1閫氳繃鐨勭數娴佷负0.5A锛R2涓2A锛屾墍浠ュ共璺渶澶х數娴佷笉瓒呰繃0.5+2=2.5A
绛旓細瑙:涓ょ伅涓茶仈鏃锛孯1鐨鍔熺巼涓4W锛屽垯锛歔U/(R1+R2)]^2*R1=4 ---(1)涓ょ伅骞惰仈鏃讹紝R1鐨勫姛鐜囦负9W 涓 閫氳繃R2鐨勭數娴佷负2A锛屽垯锛歎^2/R1=9 ---(2)U/R2=2 ---(3)鑱旂珛涓夊紡锛屽彲瑙ｅ緱锛歊1=9娆锛孯2=4.5娆э紝鐢垫簮鐢靛帇U=9V ...
绛旓細鏁匓姝ｇ‘锛汣銆丷2娑堣楃殑鍔熺巼P2=I2R2=(U2R2)2R2=U24R2锛鈭涓ょ數闃骞惰仈鍦║涓ょ鏃讹紝U2R2=2P1锛屸埓P2=U24R2=P12锛屾晠C姝ｇ‘锛汥銆佷袱鐢甸樆涓茶仈鏃讹紝鐢佃矾娑堣楃殑鎬诲姛鐜嘝=I2锛R1+R2锛=(U2R2)2锛2R2+R2锛=3U24R2锛屸埖U2R2=2P1锛屸埓P=3U24R2=32P1锛屾晠D閿欒锛涙晠閫塀C锛
绛旓細鏍规嵁骞惰仈鐢佃矾涓數闃荤殑鐗圭偣鍙煡锛歊骞舵瘮姣忎竴涓苟鑱旂數璺殑鍒嗙數闃婚兘瑕佸皬锛庡湪杩欎笁涓數闃鍊间腑锛孯骞舵渶灏忥紝鎵浠ワ紝褰撳畠浠袱绔姞鐩稿悓鐨勭數鍘嬫椂锛岄氳繃R骞剁殑鐢垫祦鏈澶э紝鏁呭畠鐨処-U鍥剧嚎鍦↖II鍖猴紟缁间笂鍒嗘瀽鏁呴塂锛
绛旓細瑙ｆ硶涓 鐢变簬鏄苟鑱旂數璺墍浠 璇ュ苟鑱旂數璺殑鎬鐢甸樆涓 R鎬=R1R2/锛圧1+R2锛=12娆у 瑙ｅ緱鐢垫簮鐢靛帇涓篣=I鎬*R鎬=12V 瑙ｆ硶浜 鐢变簬R1銆丷2骞惰仈浠栦滑涓ょ鐨勭數鍘嬫槸鐩哥瓑鐨 鍗砇1I1=R2I2 鎵浠2/I1=R1/R2=2:3 鍙堝洜涓篒2+I1=1A 鎵浠1=0.6A銆両2=0.4A 鎵浠ョ數婧愮數鍘婾=R1I1=0.6*20V=12V ...
绛旓細U1棰濆畾鐢靛帇=10*1=10V U2棰濆畾鐢靛帇=20*0.6=12V 骞惰仈鐨勬渶澶х數鍘嬪彧鑳戒负10V锛屾墍浠2=10/20=0.5A 鎵浠ュ共璺殑鐢垫祦鏈澶у=I1+I2=1+0.5=1.5A
绛旓細r1鍜宺2涓や釜鐢甸樆,涓攔1>r2,涓茶仈鍚庢帴鍦ㄧ數鍘嬩负u鐨勭數璺腑 鐢垫祦涓篿,骞惰仈鍚,鎺ュ湪鐢靛帇涓簎鐨勭數璺腑骞茶矾鐢垫祦涓16/3i 閭ｄ箞r1:r2鏄 --- 涓茶仈鏃讹細u=i*(r1+r2)骞惰仈鏃讹細u=(16/3)i*[(r1*r2)/(r1+r2)]涓ゅ紡鐩搁櫎锛(r1+r2)=(16/3)*[(r1*r2)/(r1+r2)](r1+r2)²=(16/3)*(r1*r2...
