题目内容
为了测量某待测电阻Rx的阻值(约为60Ω)。有以下一些器材可供选择:
电流表:
(量程0~50mA,内阻约10Ω)
(量程0~3A,内阻约0.12Ω)
电压表:
(量程0~3V,内阻3KΩ)
(量程0~15V,15KΩ)
电源:E(电动势为约为3V,内阻约为0.2Ω)
滑动变阻器
(0~10Ω、允许最大电流2.0A) 滑动变阻器
(0~1kΩ、允许最大电流0.5A) 单刀单掷开关S一个,导线若干
(1)电流表应选_______,电压表应选_______,滑动变阻器应选________(填字母代号)。
(2)请在方框中画出测量电阻Rx的实验电路图(要求所测量值范围尽可能大)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133730864331.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133730911191.png)
(3)测得待测电阻Rx的测量值 真实值(填大于、等于或小于),引起实验误差的原因是 。
电流表:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133730381332.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133730474354.png)
电压表:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133730521344.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133730552373.png)
电源:E(电动势为约为3V,内阻约为0.2Ω)
滑动变阻器
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133730599327.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133730662361.png)
(1)电流表应选_______,电压表应选_______,滑动变阻器应选________(填字母代号)。
(2)请在方框中画出测量电阻Rx的实验电路图(要求所测量值范围尽可能大)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133730864331.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133730911191.png)
(3)测得待测电阻Rx的测量值 真实值(填大于、等于或小于),引起实验误差的原因是 。
(1)
,
,
(填写字母即可)
(2)电路图如右图所示
(4)小于,电压表的分流作用。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133730381332.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133730521344.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133730599327.png)
(2)电路图如右图所示
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241337310672837.png)
(4)小于,电压表的分流作用。
电源电动势3V,电路中最大电流为0.05A,所以电流表应选择
,电压表选
,因为要求测量范围尽可能要大一些,所以滑动变阻器选电阻小的
,测量的电阻实际上为电压表与电阻的并联电阻,测量值偏小
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133730381332.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133730521344.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133730599327.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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