题目内容
两电阻R1和R2接在各自电路中,当U1:U2=2:1,I1:I2=4:1时,两电阻R1、R2阻值之比等于( )A.1:2
B.2:1
C.8:1
D.1:8
【答案】分析:知道电阻R1和R2的电压之比、电流之比,可利用公式R=
计算出电阻之比.
解答:解:
∵U1:U2=2:1,I1:I2=4:1,
∴电阻R1和R2阻值之比为:
=
=
×
=
=
.
故选A.
点评:本题考查了欧姆定律的应用,关键是对公式和公式变形的理解和应用,是一道较为简单的应用题,再代入数值的时候要注意.
![](http://thumb.1010pic.com/pic6/res/czwl/web/STSource/20131028160406882149514/SYS201310281604068821495005_DA/0.png)
解答:解:
∵U1:U2=2:1,I1:I2=4:1,
∴电阻R1和R2阻值之比为:
![](http://thumb.1010pic.com/pic6/res/czwl/web/STSource/20131028160406882149514/SYS201310281604068821495005_DA/1.png)
![](http://thumb.1010pic.com/pic6/res/czwl/web/STSource/20131028160406882149514/SYS201310281604068821495005_DA/2.png)
![](http://thumb.1010pic.com/pic6/res/czwl/web/STSource/20131028160406882149514/SYS201310281604068821495005_DA/3.png)
![](http://thumb.1010pic.com/pic6/res/czwl/web/STSource/20131028160406882149514/SYS201310281604068821495005_DA/4.png)
![](http://thumb.1010pic.com/pic6/res/czwl/web/STSource/20131028160406882149514/SYS201310281604068821495005_DA/5.png)
![](http://thumb.1010pic.com/pic6/res/czwl/web/STSource/20131028160406882149514/SYS201310281604068821495005_DA/6.png)
故选A.
点评:本题考查了欧姆定律的应用,关键是对公式和公式变形的理解和应用,是一道较为简单的应用题,再代入数值的时候要注意.
![](http://thumb2018.1010pic.com/images/loading.gif)
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两电阻R1和R2接在各自电路中,当U1∶U2=2∶1,I1∶I2=4∶1时,两电阻R1、R2阻值之比等于 [ ]
A.1∶2 | B.2∶1 | C.8∶1 | D.1∶8 |