几道初中物理欧姆定律计算题!(要求要写清楚步骤.)
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几道初中物理欧姆定律计算题!(要求要写清楚步骤.)
![](http://img.wesiedu.com/upload/3/ce/3ce00dae6424760b2c13aaa4cb9ad14c.jpg)
![](http://img.wesiedu.com/upload/f/9a/f9aae29deb0c2edf5b77e24cf64c0ca5.jpg)
![](http://img.wesiedu.com/upload/7/f9/7f9f301dea11da6bb155a636a496fa46.jpg)
![](http://img.wesiedu.com/upload/f/ab/fabe28a2847082f3298c14737ea4b6a9.jpg)
![](http://img.wesiedu.com/upload/e/af/eaf774d0b72ca62304c78238e597fb55.jpg)
![](http://img.wesiedu.com/upload/a/e8/ae8e095ce192495fb9a15ebbe3aaabe4.jpg)
![](http://img.wesiedu.com/upload/7/53/753ac1abad6b5322990962557c16a01b.jpg)
![](http://img.wesiedu.com/upload/7/30/730b4108f02a64be363a9d88c39a25b4.jpg)
![](http://img.wesiedu.com/upload/3/ce/3ce00dae6424760b2c13aaa4cb9ad14c.jpg)
![](http://img.wesiedu.com/upload/f/9a/f9aae29deb0c2edf5b77e24cf64c0ca5.jpg)
![](http://img.wesiedu.com/upload/7/f9/7f9f301dea11da6bb155a636a496fa46.jpg)
![](http://img.wesiedu.com/upload/f/ab/fabe28a2847082f3298c14737ea4b6a9.jpg)
![](http://img.wesiedu.com/upload/e/af/eaf774d0b72ca62304c78238e597fb55.jpg)
![](http://img.wesiedu.com/upload/a/e8/ae8e095ce192495fb9a15ebbe3aaabe4.jpg)
![](http://img.wesiedu.com/upload/7/53/753ac1abad6b5322990962557c16a01b.jpg)
![](http://img.wesiedu.com/upload/7/30/730b4108f02a64be363a9d88c39a25b4.jpg)
例3
由电路图可知,R1与R2串联,电压表测R2两端的电压,电流表测电路中的电流.
(1)当酒精气体的浓度为0时,R2的电阻为60Ω,此时电压表的示数为6V,
∵串联电路中各处的电流相等,
∴根据欧姆定律可得,电流表的示数:
I===0.1A;
(2)∵串联电路中总电压等于各分电压之和,
∴此时R1两端的电压:
U1=U﹣U2=8V﹣6V=4V,
∴R1===20Ω;
(3)调零后,R1的电阻保持不变,此时变阻器两端的电压:
U1′=I′R1=0.2A×20Ω=4V,
∴电压表的示数:
U2′=U﹣U1′=8V﹣4V=4V.
由电路图可知,R1与R2串联,电压表测R2两端的电压,电流表测电路中的电流.
(1)当酒精气体的浓度为0时,R2的电阻为60Ω,此时电压表的示数为6V,
∵串联电路中各处的电流相等,
∴根据欧姆定律可得,电流表的示数:
I===0.1A;
(2)∵串联电路中总电压等于各分电压之和,
∴此时R1两端的电压:
U1=U﹣U2=8V﹣6V=4V,
∴R1===20Ω;
(3)调零后,R1的电阻保持不变,此时变阻器两端的电压:
U1′=I′R1=0.2A×20Ω=4V,
∴电压表的示数:
U2′=U﹣U1′=8V﹣4V=4V.