题目内容
一电流表的量程标定不准确,某同学利用图1所示电路测量该电流表的实际量程Im。所用器材有:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151632977332.jpg)
量程不准的电流表
,内阻r1=10.0
,量程标称为5.0
;
标准电流表A2,内阻r2=45,量程为1.0
;
标准电阻R,阻值10
;
滑动变阻器R,总电阻约为3000
;
电源E,电动势为3.0V, 内阻不计;
保护电阻R2;开关S;导线。
回答下列问题:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241516338513701.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241516339448318.jpg)
(1)在答题卡上(图2所示)的实物图上画出连线。
(2)开关S闭合前,滑动变阻器的滑动端c应滑动至 端。
(3)开关S闭合后,调节滑动变阻器的滑动端,使电流表A1满偏;若此时电流表A2的读数为I2,则A1的量程Im= 。
(4)若测量时,A1未调到满偏,两电流表的示数如图3所示,从图中读出A1的示数I1= ,A2的示数I2= ;由读出的数据计算得Im= 。(保留3位有效数字)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082415163396012301.jpg)
(5)写一条提高测量准确度的建议:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151632977332.jpg)
量程不准的电流表
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151632993320.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151633086333.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151633211419.png)
标准电流表A2,内阻r2=45,量程为1.0
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151633211419.png)
标准电阻R,阻值10
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151633086333.png)
滑动变阻器R,总电阻约为3000
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151633086333.png)
电源E,电动势为3.0V, 内阻不计;
保护电阻R2;开关S;导线。
回答下列问题:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241516338513701.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241516339448318.jpg)
(1)在答题卡上(图2所示)的实物图上画出连线。
(2)开关S闭合前,滑动变阻器的滑动端c应滑动至 端。
(3)开关S闭合后,调节滑动变阻器的滑动端,使电流表A1满偏;若此时电流表A2的读数为I2,则A1的量程Im= 。
(4)若测量时,A1未调到满偏,两电流表的示数如图3所示,从图中读出A1的示数I1= ,A2的示数I2= ;由读出的数据计算得Im= 。(保留3位有效数字)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082415163396012301.jpg)
(5)写一条提高测量准确度的建议:
⑴连线如图
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241516339919085.jpg)
⑵阻值最大
⑶![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151634007860.png)
⑷6.05mA
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241516339919085.jpg)
⑵阻值最大
⑶
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151634007860.png)
⑷6.05mA
⑴连线如图
⑵在滑动变阻器的限流接法中在接通开关前需要将滑动触头滑动到阻值最大端]
⑶闭合开关调节滑动变阻器使待测表满偏,流过的电流为Im。根据并联电路电压相等有
得![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151634007860.png)
⑷待测表未满偏有
,将A2的示数0.66mA和其他已知条件代入有
mA
但图中A1的示数3.0mA量程为5.0mA,根据电流表的刻度是均匀的,则准确量程为6.05mA
⑵在滑动变阻器的限流接法中在接通开关前需要将滑动触头滑动到阻值最大端]
⑶闭合开关调节滑动变阻器使待测表满偏,流过的电流为Im。根据并联电路电压相等有
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151634116778.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151634007860.png)
⑷待测表未满偏有
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151634319707.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241516344441496.png)
但图中A1的示数3.0mA量程为5.0mA,根据电流表的刻度是均匀的,则准确量程为6.05mA
![](http://thumb2018.1010pic.com/images/loading.gif)
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