53. 如右圖所示之無源 RL 電路, 若 L = 2mH,R= 10Ω 及 i(0) = I0 = 5A,求電流 i(t) 之方程式? [鐵路特考 111](A)i(t) = 0.5e–5000tA(B)i(t) = 0.5e–500tA(C)i(t) = 5e–500tA(D)i(t) = 5e–5000tA