题目内容
现有一合金制成的圆柱体。为测量该合金的电阻率,现用伏安法测量圆柱体两端之间的电阻,用螺旋测微器和游标卡尺的示数如图(a)和图(b)所示。
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500493843333220.png)
(1)由上图读得圆柱体的直径为_________mm,长度为__________cm。
(2)若流经圆柱体的电流为I,圆柱体两端之间的电压为U,圆柱体的直径和长度分别用D、L表示,则用D、L、I、U表示的电阻率的关系式为
=____________。
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500493843333220.png)
(1)由上图读得圆柱体的直径为_________mm,长度为__________cm。
(2)若流经圆柱体的电流为I,圆柱体两端之间的电压为U,圆柱体的直径和长度分别用D、L表示,则用D、L、I、U表示的电阻率的关系式为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004938448311.png)
(1)
,
(2)![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004938511723.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004938464431.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004938495451.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004938511723.png)
试题分析:(1)螺旋测微器的读数为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250049385261122.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250049385421230.png)
(2)圆柱体的横截面积为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004938558916.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004938573590.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004938589519.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004938620827.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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