将标有“6V,3W”、“6V,6W”的甲、乙两个灯泡,串联接在9V的电源上,它们的实际功率分别是_ W和_ W.

问题描述:

将标有“6V,3W”、“6V,6W”的甲、乙两个灯泡,串联接在9V的电源上,它们的实际功率分别是______ W和______ W.

(1)灯泡电阻R1=

U 21
P1
=
(6V)2
3W
=12Ω,R2=
U 22
P2
=
(6V)2
6W
=6Ω;
(2)两灯泡串联时,电路电流I=
U
R1+R2
=
9V
12Ω+6Ω
=0.5A;
(3)灯泡实际功率P1实=I2R1=(0.5A)2×12Ω=3W,
P2实=I2R2=(0.5A)2×6Ω=1.5W;
故答案为:3;1.5.