[問題] 電磁學cheng的習題題意

看板Grad-ProbAsk作者larry0208 (littleyellow)時間15年前 (2009/03/24 17:56)推噓1(1推 0噓 7→)

留言8則, 2人參與討論串1/2 (看更多)

Problem P.4-2 A long, round wire of radius "a" and conductivity "σ" is coated with a material of conductivity "0.1σ" a) What must be the thickness of the coating so that the resistance per unit length of the uncoated wire is reduces by 50% ? 關於問題a 我覺得是膠線的厚度應為多少，內部的電阻會變成原來的一半可是內部的參數(σ 面積長度)都沒變阿，外部的參數怎麼會影響內部的電阻？還是要用到電子學的觀念，電流流多的電阻變小？請眾高手幫忙解惑~"~ -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 125.230.156.236

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larry0208

03/24 18:20, , 1^F

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geminison

03/24 18:38, , 2^F

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geminison

03/24 18:39, , 3^F

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