139. 如下圖所示電路，若量測得電流 I = 4.5A，則電壓 Va 為何？統測 113 (A)4V (B)6V (C)8V (D)10V

145. 以 KCL 求解右圖示電路時，下列何者為節點 Vb 之正確表示式？初等考 114 (A)(Vb – Va)/R1 + Vb /R3 + (Vb – Vc)/R2 = 0 (B)(Vb – Va)/R1 + Vb /R3 + (Vb – Vc)/R2 + R4 = 0 (C)(Vb – Va)/R1 + Vb /R3 –(Vb – Vc)/R2 = 0 (D)(Vb – Va)/R1 + (Vb – Vc)/R2 = 0