如图所示,电源电压U保持不变,灯泡L标有“6V 3W”字样.当开关S
1 , S
2都闭合,滑片P移到最左端时,电流表的示数为I,电压表V
1、V
2和V
3的示数分别为U
1、U
2和U
3 , R1消耗的功率为P
1 , 电路消耗的总功率为P;当开关S
1闭合,S
2断开,滑片P移到最右端时,电流表的示数为I′,电压表V
1、V
2和V
3的示数分别为U
1′、U
2′和U
3′,R
1消耗的功率为P
1′,电路消耗的总功率为P′.此时灯泡L恰好正常发光.已知U
1:U
3=2:3,U
1′:U
3′=5:2. 下列表达式不正确的是( )
![](http://tikupic.21cnjy.com/60/e9/60e9763abbf3ad189aeab7ab8a4e3671.png)
- A、
=
,
= ![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmfrac%3E%3Cmn%3E2%3C%2Fmn%3E%3Cmn%3E3%3C%2Fmn%3E%3C%2Fmfrac%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
- B、
=
,
= ![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmfrac%3E%3Cmn%3E2%3C%2Fmn%3E%3Cmn%3E5%3C%2Fmn%3E%3C%2Fmfrac%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
- C、
=
,
= ![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmfrac%3E%3Cmn%3E3%3C%2Fmn%3E%3Cmn%3E5%3C%2Fmn%3E%3C%2Fmfrac%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
- D、
=
,
= ![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmfrac%3E%3Cmn%3E2%3C%2Fmn%3E%3Cmn%3E3%3C%2Fmn%3E%3C%2Fmfrac%3E%3C%2Fmrow%3E%3C%2Fmath%3E)