Positive SSL
    14.素養(4)
1 如圖所示電路,若 E 及 R1為固定值,且當 R2=2Ω時,V2=10V;當 R2=8Ω時,V2=16V。當 R2=18Ω時,則 V2為何? 112 統測
A 20V
B 19V
C 18V
D 17V

條件1:

I = 10/2 = 5A

E = 5R1 + 10 - - - (1)


條件2:

I = 16/8 = 2A

E = 2R1 + 16 - - - (2)


(2) - (1) ⟹ -3R1 + 6 = 0

R1 = 2 Ω 代入 (2)

E = 2 × 2 + 16 = 20 V


V2 = 20 × 182+18 = 18V