题目内容
在测定金属丝电阻率的实验中,如图甲所示,用螺旋测微器测得金属丝的直径d=____ _____mm。如图乙所示,用多用电表的“×1”欧姆挡,调零后测得金属丝阻值R=______ ___Ω,若实验中测出金属丝的长度为L,通过伏安法测得的电阻与多用表所测非常接近,则该金属丝电阻率的表达式ρ=_________(用符号表示)。![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082412582143836366.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082412582143836366.png)
0.730 8 ![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125821469581.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125821469581.png)
用螺旋测微器测得金属丝的直径d=0.5mm+23.0×0.01mm=0.730mm
金属丝阻值R=8Ω
根据
,若实验中测出金属丝的长度为L,则该金属丝电阻率的表达式ρ=![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125821516906.png)
故答案为:0.730 8![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125821469581.png)
金属丝阻值R=8Ω
根据
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125821485590.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125821516906.png)
故答案为:0.730 8
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125821469581.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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