A、
=I1 I2
=
U
R1+R2
U R1
=R1
R1+R2
=2R2
3R2
.不符合题意.2 3
B、
=U1 U2
=
I1R1
I2R1
=I1 I2
.不符合题意.2 3
C、
=P P′
=
U2
R1+R2
U2
R1R2
R1+R2
=
1
R1+R2
R1+R2
R1R2
=
R1R2
(R1+R2)2
=2
R
(3R2)2
.符合题意.2 9
D、
=P1
P
=(
R1
I
R1
I
)2=(I1 I2
)2=2 3
.不符合题意.4 9
故选C.