14. 如右圖所示之電路，試求I值為何？(A) 5 mA(B) 10 mA(C) 15 mA(D) 20 mA

21. 如右圖所示之電路，當\( Z \)為多少值時可得\( P_Z(\text{Max}) \)值？另試求\( P_Z(\text{Max}) \)值為何？ (A) \( Z = 8 - j8 \ \Omega \) 及 \( P_Z(\text{Max}) = 180 \ \text{W} \) (B) \( Z = 14 - j14 \ \Omega \) 及 \( P_Z(\text{Max}) = 500 \ \text{W} \) (C) \( Z = 14 - j8 \ \Omega \) 及 \( P_Z(\text{Max}) = 250 \ \text{W} \) (D) \( Z = 8 + j14 \ \Omega \) 及 \( P_Z(\text{Max}) = 360 \ \text{W} \)