[試題] 108-2 毛紹綱電磁學(二) 小考

看板NTU-Exam作者chun10396974 (娜嗲希口老公)時間5年前 (2020/04/24 14:59)推噓0(0推 0噓 0→)

留言0則, 0人參與討論串1/1

課程名稱︰電磁學(二) 課程性質︰電機工程學系大二必修課程教師︰毛紹綱開課學院：電機資訊學院開課系所︰電機工程學系考試日期（年月日）︰2020/4/17 考試時限（分鐘）：10:20-12:10 試題 : 1. In the system shown in Fig.1, the switch is closed at t = 0. Assume source voltage Vg(t) to be a direct voltage of 60 V, please draw (a) the line vol- age and (b) the line current bounce diagrams (up to t = 5μs). Then, please sketch (c) the voltage and (d) the line current versus z for t = 2.75μs. Fig.1 https://imgur.com/1mcNQp1

Time domain analysis of a transmission-line system. 2. In the system shown in Fig.2.1, an incident wave of voltage V+(V+ = 60V) strikes the discontinuity from the left, i.e. from line 1. (a) please find the reflected wave voltage into line 1. Fig.2.1 https://imgur.com/S8h4B6a

Reflection at a transmission-line discontinuity. (b) Now, let's try to consider the transmission line system in Fig.2.2 where a (+) wave carrying power P is incident on the junction a-a'from line 1 connected to the other two lines (line 2 and line 3). Please find: (i) the power reflected into line 1; (ii) the power transmitted into line 2; (iii) the power transmitted into line 3; Fig.2.2 https://imgur.com/ohDLDIy

Reflection at a junction involving three lines. (c) Lastly, in the system shown in Fig.2.3, a (+) wave carrying power P is incident on the junction a-a' from line 1 connected to a junction cons- isting of three lines and a resistive network. Please find the value of R for which there is no reflected wave into line 1. Fig.2.3 https://imgur.com/rjxWhif

A system of three lines with a resistive network at the junction. 3. In the system shown in Fig.3, the switch S is closed at t = 0, with the lines uncharged and with zero current in the inductor. Please calculate the solution for the line voltage versus time at (a) z = 0 and (b) z = l+. Fig.3 https://imgur.com/dwL0PlQ

A system of two lines with an inductance at the junction. 4. In the system shown in Fig.4 (a), the switch S is closed at t = 0. The line voltage variations with time at z = 0 and z = l for the first 5μs are observed to be as shown in Fig.4 (b) and (c), respectively. (a) Find the values of Vo, Rg, RL, and T. (b) Plot the line current variations with time at z = 0 and z = l for the first 7μs. Fig.4 https://imgur.com/Y6GSbbW

5. The system shown in Fig.5 consists of a series inductor of value 200 nH at the junction between the two lines. Assume that the inductor is initially of zero current. (a) Please plot line voltage and current variations with time at the input z = 0. (b) Also clearly mark the steady state voltage and current. Fig.5 https://imgur.com/ZToOP9T

6. Two parallel transmission lines are aligned in the z direction as shown in Fig.6a. The distributed circuit model of weakly coupling between these two transmission line is shown in Fig.6b. Lm and Cm are per-unit-length mutual inductance and mutual capacitance, repectively. With time-domain weakly coupling analysis, we know that forward and backward crosstalk voltage are V2+(z,t) = zKfV1'(t-z/vp) V2-(z,t) = Kb[V1(t-z/vp)-V1(t-2l/vp + z/vp)] respectively. If Vg(t) in Fig.6a is 4Vo cos^2(pit/2T) , for 0 < t < T Vg(t) = 0 , otherwise please answer the following questions: (a) Find V2+(l,t) (b) Find V2-(0.75l,t) (Note:For the above two questions, you have to list all answers with its corresponding t regions respectively). (c) Plot V2+(l,t) in Fig.6a from t = 0 up to t = 2T. (d) Plot V2-(0.75l,t) in Fig.6b from t = 0 up to t = 2.5T (e) If we have known Lm = 0.16μH/m and Cm = 3.8pF/m in Fig.6b, please calculate forward and backward coefficient Kf & Kb. Assume Zo = 200Ω and vp = 0.125 × 10^9 m/s in Fig.6a. Fig.6 https://imgur.com/Hx5VzIb