题目内容
在“探究导体电阻与其影响因素的定量关系”试验中,为了探究3根材料未知、横截面积均为S=0.20mm2的金属丝a、b、c的电阻率,采用如图所示的实验电路,M为金属丝a的左端点,O为金属丝a的右端点,P是金属丝上可移动的接触点。在实验过程中,电流表读数始终为
,电压表读数
随
间距离
的变化如下表:![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082412422662316133.png)
(1)绘出电压表读数U随OP间距离x变化的图线;
(2)求出金属丝的电阻率p,并进行比较。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124226420556.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124226435325.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124226498376.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124226576271.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082412422662316133.png)
x/mm | 600 | 700 | 800 | 900 | 1000 | 1200 | 1400 | 1600 | 1800 | 2000 | 2100 |
U/V | 3.95 | 4.50 | 5.10 | 5.90 | 6.50 | 6.65 | 6.82 | 6.93 | 7.02 | 7.15 | 7.85 |
x/mm | 2200 | 2300 | 2400 |
U/V | 8.50 | 9.05 | 9.75 |
(1)绘出电压表读数U随OP间距离x变化的图线;
(2)求出金属丝的电阻率p,并进行比较。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124226825132441.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082412422748168263.png)
分析:根据R=ρ
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124227715424.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124227746404.png)
解:(1)以OP间距离x为横轴,以电压表读数U为纵轴,描点、连线绘出电压表读数U随OP间距离x变化的图线
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082412422793338186.png)
(2)根据电阻定律R=ρ
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124227715424.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124228370426.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124227746404.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124228370426.png)
ρa=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241242284481442.png)
ρb=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241242284791438.png)
ρc=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241242284951500.png)
通过计算可知,金属丝a与c电阻率相同,远大于金属丝b的电阻率.
![](http://thumb2018.1010pic.com/images/loading.gif)
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