两电阻R1和R2接在各自电路中,当U1:U2=2:1,I1:I2=4:1时,两电阻R1、R2阻值之比等于(  ) A.1:2 B.2:1 C.8:1 D.1:8

问题描述:

两电阻R1和R2接在各自电路中,当U1:U2=2:1,I1:I2=4:1时,两电阻R1、R2阻值之比等于(  )
A. 1:2
B. 2:1
C. 8:1
D. 1:8


∵U1:U2=2:1,I1:I2=4:1,
∴电阻R1和R2阻值之比为:

R1
R2
=
U1
I1
U2
I2
=
U1
I1
×
I2
U2
=
2×1
1×4
=
1
2

故选A.