如图所示,电源电压为8V,电阻R1=4R2,电流表的示数为0.2A;求电阻R1和R2的电阻值各为多少欧姆?
问题描述:
如图所示,电源电压为8V,电阻R1=4R2,电流表的示数为0.2A;求电阻R1和R2的电阻值各为多少欧姆?
答
(1)∵I=
,∴电路总电阻R=U R
=U I
=40Ω;8V 0.2A
(2)两电阻并联,则
=1 R
+1 R1
=1 R2
+1 4R2
=1 R2
,5 4R2
R2=
R=5 4
×40Ω=50Ω,R1=4R2=4×50Ω=200Ω;5 4
答:电阻R1和R2的电阻值分别是200Ω与50Ω.