6. 如下圖電路所示,流過 R1 及 R2 之電流比為 1:2,則 R1 及 R2 之值各為多少?
(A)R1 =18Ω、R2 =9Ω (B)R1 =20Ω、R2 =10Ω (C)R1 =16Ω、R2 =8Ω (D)R1 =30Ω、R2 =15Ω。