题目内容
(8分)某同学采用伏安法测定一段阻值约为5
左右的金属丝的电阻。有以下器材可供选择:(要求测量结果尽量准确)
A.电池组(3V,内阻约1
)
B.电流表(0—3A,内阻约0.025
)
C.电流表(0—0.6A,内阻约0.125
)
D.电压表(0—3V,内阻约3k
)
E.电压表(0—15V,内阻约15k
)
F.滑动变阻器(0—20
,额定电流1A)
G.滑动变阻器(0—1000
,额定电流0.3A)
H.开关,导线
实验时应选用的器材是 (填写各器材的字母代号)。
请在下面的虚线框中画出实验电路图。
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250030566505816.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500305666619251.png)
这位同学在一次测量时,电流表、电压表的示数如上图所示。由图中电流表、电压表的读数可计算出金属丝的电阻为
。
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003056338335.png)
A.电池组(3V,内阻约1
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003056338335.png)
B.电流表(0—3A,内阻约0.025
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003056338335.png)
C.电流表(0—0.6A,内阻约0.125
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003056338335.png)
D.电压表(0—3V,内阻约3k
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003056338335.png)
E.电压表(0—15V,内阻约15k
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003056338335.png)
F.滑动变阻器(0—20
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003056338335.png)
G.滑动变阻器(0—1000
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003056338335.png)
H.开关,导线
实验时应选用的器材是 (填写各器材的字母代号)。
请在下面的虚线框中画出实验电路图。
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250030566505816.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500305666619251.png)
这位同学在一次测量时,电流表、电压表的示数如上图所示。由图中电流表、电压表的读数可计算出金属丝的电阻为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003056338335.png)
ACDFH 电路图如下图所示 5.2Ω
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250030567131653.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250030567131653.png)
试题分析:根据欧姆定律
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003056728535.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003056760607.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003056775698.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003056791753.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003056806856.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250030568381653.png)
根据电表读数原理及要求可读出U=2.40V,I=0.46A,则
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003056853787.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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