有三个电阻并联在电路中 一个100欧 一个300欧 一个500欧 那么总电阻是多 为什么并联电路中并联电阻个数越多总电阻越小...

\u7528\u4e09\u4e2a100\u6b27,1w\u7684\u7535\u963b\u4e32\u8054\u548c\u4e00\u4e2a300\u6b27,10w\u7684\u7535\u963b\u5e76\u8054,\u4f5c\u4e3a150\u6b27\u7684\u7535\u963b\u4f7f\u7528

\u4e09\u4e2a100\u6b27\u59c6\u4e32\u8054\uff0c\u6bcf\u4e2a\u529f\u73871w \u5219\u6b64\u652f\u8def\u51713w\u3002\u56e0\u6b64\uff0c\u4e09\u4e2a\u4e32\u8054\u7535\u963b\u4e24\u7aef\u6700\u5927\u7535\u538bu^2=pR=3*300=900
\u5219u=30v\u3002\u56e0\u4e3a300\u6b27\u59c6\u7535\u963b\u4e0e\u4e09\u4e2a\u4e32\u8054\u540e\u5e76\u8054\uff0c\u6240\u4ee5\u5b83\u4e24\u7aef\u7535\u538b\u4e5f\u4e3a30v\uff0c\u90a3\u4e48\u8fd9\u8def\u7535\u963b\u7684\u529f\u7387\u4e3a\uff1aP'=U^2/R=30^2/300=3w
\u56e0\u6b64\uff0c\u603b\u529f\u73873w+3w=6w

1.\u4e00\u4e2a1\u6b27,2\u6b27,4\u6b27\u7684\u5e76\u8054\u603b\u7535\u963b\u662f4/7,\u8fd9\u662f3\u4e2a\u7535\u963b\u5e76\u8054\uff0c\u53ef\u4ee5\u518d\u589e\u52a0\u4e00\u4e2a5\u6bb4\u7684\u7535\u963b\uff0c\u6b64\u65f6\u8fd94\u4e2a\u7535\u963b\u7684\u5e76\u8054\u7535\u963b\u662f20/39 \u80af\u5b9a\u5c0f\u4e8e\u524d\u9762\u76843\u4e2a\u7535\u963b\u5e76\u8054\u7684\u3002 \u9898\u76ee\u7684\u9690\u542b\u610f\u601d\u662f \u589e\u52a0\u65f6\u5e94\u4fdd\u5b58\u539f\u6709\u7684\u4e0d\u53d8\u3002 \u770b\u6765\u4f60\u7684\u8bed\u6587\u5e94\u8be5\u52a0\u5f3a\u3002

2.\u4f8b\u5982\u4f60\u5bb6\u6709\u5f69\u7535\u7684\u7535\u963b\u662f100\u6b27\uff0c\u5fae\u6ce2\u7089\u7684\u7535\u963b\u662f200\u6bb4\uff0c\u6d17\u8863\u673a\u662f300\u6b27\uff0c\u540c\u65f6\u5de5\u4f5c\u65f6\u662f\u5e76\u8054\u7684\uff0c3\u4e2a\u5bb6\u7528\u7535\u5668\u7684\u5e76\u8054\u7535\u963b\u662f600/11,\u4eca\u5929\u4f60\u5bb6\u53c8\u5b89\u88c5\u4e86\u7a7a\u8c03\uff0c\u7535\u963b\u662f50\u6b27\uff0c\u6b64\u65f6\u662f4\u4e2a\u5bb6\u7528\u7535\u5668\u540c\u65f6\u5de5\u4f5c\uff0c\u6b64\u65f6\u5e76\u8054\u7684\u603b\u7535\u963b\u662f600/23,\u53ef\u89c1\u4f60\u5bb6\u540c\u65f6\u5de5\u4f5c\u7684\u5bb6\u7528\u7535\u5668\u8d8a\u591a\uff0c\u5e76\u8054\u7684\u603b\u7535\u963b\u8d8a\u5c0f\uff0c\u800c\u7535\u538b\u662f220v,\u8fd9\u6837\u7535\u6d41\u5c31\u8d8a\u591a\uff0c\u7528\u7535\u5c31\u8d8a\u591a\u4e86\u3002\u6240\u4ee5\u8bf4;\u5e76\u8054\u7535\u8def\u4e2d\u5e76\u8054\u7535\u963b\u4e2a\u6570\u8d8a\u591a\u603b\u7535\u963b\u8d8a\u5c0f.

R并
= R1×R2×R3/(R2×R3+R1×R3+R1×R2)

= 100×300×500/(300×500+100×500+100×300)

= 100×3×5/(3×5+1×5+1×3)

= 1500 / 23
≈ 65.22

总电阻R=1/(1/100+1/300+1/500)=1500/23欧

1/（1/100+1/300+1/500）=65.21739130434783欧

1500/23欧姆

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