一只灯泡上标有“12V 12W”的字样,(若不考虑温度对灯丝电阻的影响)则(1)这只灯泡的额定电流是 __

2025-05-06 15:31:03
推荐回答(1个)
回答(1):

(1)I=

P
U
12W
12V
=1A,电阻R=
U
I
12V
1A
=12Ω

(2)分担电压U1=U-U=15V-12V=3V,串联电阻R
U1
I
3V
1A
=3Ω

(3)P
U
R
(9V)2
12Ω
=6.75W
,额定功率不变为12W.
(4)P1=I12R=(0.8A)2×12Ω=7.68W.
(5)I2= 
P2
R
 =
3W
12Ω
=0.5A

(6)P3
U
R
(
4
5
U)
2
R
16
25
×
U
R
16
25
P

故答案为:1;12;串;3;6.75;12;7.68;0.5;
16
25