(1)灯泡电阻R甲=
=
U
P甲
=3Ω,R乙=(6V)2 12W
=
U
P乙
=24Ω;(12V)2 6W
灯泡的额定电流I甲=
=P甲 U甲
=2A,I乙=12W 6V
=P乙 U乙
=0.5A;6W 12V
(2)两灯串联时,流过电路的电流I=I乙=0.5A,
串联电阻两端的电压U串=I(R甲+R乙)=0.5A×(3Ω+24Ω)=13.5V;
消耗的实际功率之比
=P甲 P乙
=
I2R甲
I2R乙
=R甲 R乙
=3Ω 24Ω
;1 8
(3)两灯泡并联时,
=1 R并
+1 R甲
,R并=1 R乙
=
R甲R乙
R甲+R乙