题目内容
两只电阻的伏安特性曲线如图所示,则下列说法中正确的是
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241606235497607.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241606235497607.png)
A.两电阻的阻值为R1大于R2 |
B.两电阻串联在电路中时,R1消耗的功率小于R2消耗的功率 |
C.两电阻并联在电路中时,R1的电流小于R2的电流 |
D.两电阻串联在电路中时,R1两端电压大于R2两端电压 |
B
试题分析:本题为图象分析问题,在图中任意做一条与纵轴垂直的直线,则与两图象的交点为电流相同点,对应的横坐标得出电压值,则由欧姆定律可进行比较电阻.两电阻串联在电路中时,电流相等,两电阻并联在电路中时,电压相等.
A.由下图可知,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241606236744027.jpg)
当电流相同时,R2两端的电压大于R1两端的电压,即U2>U1,由欧姆定律
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160623690429.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160623799430.png)
B.两电阻串联在电路中时,电流相等,根据P=I2R可知:R1消耗的功率小于R2消耗的功率,故B正确;
C.两电阻并联在电路中时,电压相等,根据
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160624002431.png)
D.两电阻串联在电路中时,电流相等,根据A的分析可知:即U2>U1,故D错误.
故选B.
点评:本题为图象分析问题,要能从图象中得出有效信息,两电阻串联在电路中时,电流相等,两电阻并联在电路中时,电压相等.
![](http://thumb2018.1010pic.com/images/loading.gif)
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