题目内容
近年来,酒驾几乎成为一种“社会公害”,交警用来检测酒驾的酒精测试仪的工作原理如图所示,其中P是半导体型酒精气体传感器,该传感器的电阻r′的倒数与酒精气体的浓度C成正比,R为定值电阻.以下关于电流表的示数I与酒精气体浓度C之间的关系的图象,正确的是( )![](http://thumb.1010pic.com/pic6/res/gzwl/web/STSource/20131029191400599810810/SYS201310291914005998108002_ST/images0.png)
A.
![](http://thumb.1010pic.com/pic6/res/gzwl/web/STSource/20131029191400599810810/SYS201310291914005998108002_ST/images1.png)
B.
![](http://thumb.1010pic.com/pic6/res/gzwl/web/STSource/20131029191400599810810/SYS201310291914005998108002_ST/images2.png)
C.
![](http://thumb.1010pic.com/pic6/res/gzwl/web/STSource/20131029191400599810810/SYS201310291914005998108002_ST/images3.png)
D.
![](http://thumb.1010pic.com/pic6/res/gzwl/web/STSource/20131029191400599810810/SYS201310291914005998108002_ST/images4.png)
【答案】分析:由传感器的电阻r′的倒数与酒精气体的浓度C成正比,得到
=kC,k为比例系数,根据闭合电路欧姆得出电流的表达式,根据数学知识分析电流与C是线性关系还是非线性关系.应用数学变形得出电流的倒数与C的关系,分析
与C是线性关系还是非线性关系,再选择图象.
解答:解:A、B由传感器的电阻r′的倒数与酒精气体的浓度C成正比,得到
=kC,k为比例系数,根据闭合电路欧姆得
I=
=
,可见电流与C是非线性关系,图象是曲线,故AB错误.
C、D将上式变形得
=
,可见
与
是线性关系,而且是增函数,故C正确,D错误.
故选C
点评:本题考查利用物理知识分析科技装置原理的能力,关键是应用数学变形将非线性关系变成线性关系,这种方法在一些实验中常常用到.
![](http://thumb.1010pic.com/pic6/res/gzwl/web/STSource/20131029191400599810810/SYS201310291914005998108002_DA/0.png)
![](http://thumb.1010pic.com/pic6/res/gzwl/web/STSource/20131029191400599810810/SYS201310291914005998108002_DA/1.png)
解答:解:A、B由传感器的电阻r′的倒数与酒精气体的浓度C成正比,得到
![](http://thumb.1010pic.com/pic6/res/gzwl/web/STSource/20131029191400599810810/SYS201310291914005998108002_DA/2.png)
I=
![](http://thumb.1010pic.com/pic6/res/gzwl/web/STSource/20131029191400599810810/SYS201310291914005998108002_DA/3.png)
![](http://thumb.1010pic.com/pic6/res/gzwl/web/STSource/20131029191400599810810/SYS201310291914005998108002_DA/4.png)
C、D将上式变形得
![](http://thumb.1010pic.com/pic6/res/gzwl/web/STSource/20131029191400599810810/SYS201310291914005998108002_DA/5.png)
![](http://thumb.1010pic.com/pic6/res/gzwl/web/STSource/20131029191400599810810/SYS201310291914005998108002_DA/6.png)
![](http://thumb.1010pic.com/pic6/res/gzwl/web/STSource/20131029191400599810810/SYS201310291914005998108002_DA/7.png)
![](http://thumb.1010pic.com/pic6/res/gzwl/web/STSource/20131029191400599810810/SYS201310291914005998108002_DA/8.png)
故选C
点评:本题考查利用物理知识分析科技装置原理的能力,关键是应用数学变形将非线性关系变成线性关系,这种方法在一些实验中常常用到.
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目