图示直流电路,当R<sub>1</sub>=R<sub>2</sub>时,电阻R<sub>1</sub>两端电压为<img src="https://img.ppkao.com/2017-12/xieqiushi/2017120714504555908.jpg" />;当R<sub>1</sub>=2R<sub>2</sub>时,R<sub>1</sub>两端电压为<img src="https://img.ppkao.com/2017-12/xieqiushi/2017120714511442657.jpg" />,则<img src="https://img.ppkao.com/2017-12/xieqiushi/2017120714512334294.jpg" />等于()<br /> <img src="https://img.ppkao.com/2017-12/xieqiushi/2017120714503428497.jpg" /><p> 图示直流电路,当R<sub>1</sub>=R<sub>2</sub>时,电阻R<sub>1</sub>两端电压为<img src="https://img.ppkao.com/2017-12/xieqiushi/2017120714504555908.jpg" />;当R<sub>1</sub>=2R<sub>2</sub>时,R<sub>1</sub>两端电压为<img src="https://img.ppkao.com/2017-12/xieqiushi/2017120714511442657.jpg" />,则<img src="https://img.ppkao.com/2017-12/xieqiushi/2017120714512334294.jpg" />等于()<br /> <img src="https://img.ppkao.com/2017-12/xieqiushi/2017120714503428497.jpg" /></p>
A、A.2
B.
C.
D.