题目内容
⑴ 如图所示,有一个表头G,满偏电流为Ig =" 1" mA,内阻Rg ="100" Ω,用它改装为有5 V和50 V两种量程的电压表,则R1 =_____________Ω、R2 = _____________Ω。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241231240271599.png)
⑵ 如图所示,有一个表头G,满偏电流Ig =" 500" mA,内阻Rg=200Ω,用它改装为有1 A和10 A两种量程的电流表,则R1 = ______Ω、R2 = ______Ω。![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241231240432929.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241231240271599.png)
⑵ 如图所示,有一个表头G,满偏电流Ig =" 500" mA,内阻Rg=200Ω,用它改装为有1 A和10 A两种量程的电流表,则R1 = ______Ω、R2 = ______Ω。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241231240432929.png)
(1) 4900 , 45000 , (2) 180 , 20
解答:解:(1)接5V量程时,为串联的R1,则R1=
-Rg=
-100=4900Ω
接10V量程时,为串联的R1和R2,则R2=
-Rg-R1=
-100-4900=45000Ω
(2)接1A量程时,为并联的R1和R2,接10A量程时,则
,为表头串联的R1,然后与R2并联,则
,联立两式可得R1 =180Ω,R2 =20Ω
故答案为:(1)4900,45000;(2)180,20
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123124058497.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123124089545.png)
接10V量程时,为串联的R1和R2,则R2=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123124105522.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123124152520.png)
(2)接1A量程时,为并联的R1和R2,接10A量程时,则
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123124167814.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123124214963.png)
故答案为:(1)4900,45000;(2)180,20
![](http://thumb2018.1010pic.com/images/loading.gif)
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