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
答
∵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.