99-2 電機與電子群 專業科目(一) 共3 頁 第 1 頁
九十九學年四技二專第二次聯合模擬考試
電機與電子群 專業科目(一) 詳解
99-2-03-4 99-2-04-4 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 A D A C D C C A A C B D A D B A C A D B D A B C C 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 D B C D C A B A D A D C B C B A B A D B C D B D A第一部份:基本電學
1. 0.85 P 425W 500 P o 2 o =η = ⇒ = i i 2 1 i o 0.7 0.85 P P 425 P P =η ×η ⇒ = × ⇒ ≒714 W ∴Ploss=714−425≒290 W 2. 長度拉長 3 倍⇒截面積縮小為 3 1倍 R 9 A 9 A 3 1 3 ' R=ρ⋅ ⋅l = ⋅ρ⋅l = 3. 80 1 20 1 70 1 1 5 . 1 ] t 1 [ R R ] t 1 [ R R o o o 1 o o 1 2 o o 2 ⇒α = × α + × α + = ⇒ ⎩ ⎨ ⎧ ⋅ α + ⋅ = ⋅ α + ⋅ = 4. 2A ) 28 // 7 ( 4 . 2 16 IT = + = 5. 6A 8 // ] 6 ) 6 // 3 [( 2 36 IT = + + = A 3 8 8 8 A 6 I1 = + × = A 2 6 3 6 A 3 I2 = + × = ∴I=IT−I2 =6−2=4A 6. Vx=12−2×(2+2)=4V 7. 2A (6//12) 3 14 I = + = A 3 4 12 6 12 A 2 I1 = + × = ∴ W 3 16 3 ) 3 4 ( P3Ω= 2× Ω= 8 = = Ω 2 3 2 // 6 Rth V 3 Vth = 當 = = Ω 2 3 R RL th 則 = Ω × = 1.5 2 3 4 3 Pmax 2 9. 2A 5 20 I1= = , 1A 10 10 I2= = 故I1>I2⇒5 Ω/20 W 耐電流較大 10. , ∴IN= 'I+I''+ 'I''=2A 11. QT =150×[[(6+3)//18+9]//30]=1500μC C 600 ] 18 // ) 3 6 [( 9 ] 18 // ) 3 6 [( C 1500 Q18 F = μ + + + × μ = μ C 200 3 6 3 C 600 Q3 F = μ + × μ = μ 12. 3 5 2 A 2.5 10 10 2 10 5 Q F E = × × × = = −− V/m 13. LT =L1+L2+L3+2M−2M−2M H 7 2 2 2 3 6+ + − × = = J 5 . 87 5 7 2 1 I L 2 1 W 2 2 T LT = × = × × = 14. 10V 1 2 4 5 eab=− × − =− , 6V 1 2 4 3 ecd=− × − =− 16. SWÆ199-2 電機與電子群 專業科目(一) 共3 頁 第 2 頁 SWÆ2 sec) 2 1 ( e 3 ) t ( iL = ⋅ −2t τ= ∴Vo=−2×iL(t)=−6⋅e−2t ∴t 1sec V 6 e 2 0.81V o =− × =− ⇒ = − 17. SW 打開前: SW 打開後: sec 5 . 2 2 1 ) 2 3 ( + × = = τ ) V ( ) e 1 ( 18 e 12 V 2.5 t t 5 . 2 1 c − − − + ⋅ = 5 . 2 t c 2 (18 V) 322 125 e V Ω = ⋅ − + × − = ∴t=5sec,∴V2Ω =2.4⋅e−2(V) 18. ○1 SW 閉合前⇒iL =1.8A ○2 SW 閉合(瞬間) V 4 . 14 i 8 VL = × L = 19. i(t)=5sin314t(A) ) V ( ) 60 t 314 sin( 40 ) 30 t 314 cos( 40 ) t ( V =− + ° = ⋅ − ° (A) f =50Hz (B) 電路呈電容性 (C) = ∠− °Ω ° ∠ ° − ∠ = = 8 60 0 2 5 60 2 40 I V Z 20. 6 2 ) 3 1 ( 1 ) 1 ( 1 3 2 ) 3 2 ( V 2 2 2 2 rms × + × − + × + × = V 3 5 2 = 21. i1(t)=10⋅sin50t,i2(t)=10⋅sin(50t+90°) A 45 10 2 10 j 0 2 10 I I1+ 2= ∠ °+ = ∠ ° A 2 10 ) I I (1+ 2 max= 22. L L L L jX 16 jX 6 . 0 R X j R X R j R Z 6 . 0 PF + = ⇒ ⋅ + ⋅ ⋅ = = = L 2 L 2 L L jX 9.6 (0.6X ) X X 6 . 0 j 6 . 9 + ⋅ ⋅ = ⇒ + = ⇒ Ω = ⇒ = + ⇒9.62 0.36XL2 XL2 XL 12 23. 10 60 A 3 j 30 30 jX V I C C = ∠ ° − ° − ∠ = − = ° − ∠ × ° ∠ = − × ° ∠ = × =I Z 10 60 (4 j3) 10 60 5 37 V ) V ( 23 50∠ ° = ∴V(t)=50 2⋅sin(377t+23°)(V) ) V ( ) 67 t 377 cos( 2 50 − ° = 24. Z=0.5+j3.5+[(4−j3)//(3+j4)] Ω ° ∠ = + = + + + =0.5 j3.5 3.5 j0.5 4 j4 4 2 45 ∴ 45 A 2 25 45 2 4 100 Z V IT = ∠− ° ° ∠ = = 25. ○1 SW 閉合前 Ω = ⇒ = = Z 20 Z 12 Z R 6 . 0 ∴ 12−jXC =20⇒XC=16Ω ○2 SW 閉合後 Ω = ⇒ ± = Ω =20 12 jX X 16 Z ∴ 16 ) 16 X ( X 16 16 j jX ) 16 j // jX ( L L L − =m ⋅ ⇒ ± = ± = − ) )( X 16 ( ) 16 X ( XL = L− =± − L + ⇒ m 取 Ω = ⇒ =16 X 8 X 2 L L
第二部份:電子學
26. ⎪⎩ ⎪ ⎨ ⎧ μ = × = s 1 T % 100 T T % 20 P P s 5 T 2 . 0 T s 1μ = ⇒ = μ ⇒ ∴ 200kHz T 1 f = = 27. (B) 二極體在逆向偏壓時為過渡電容,範圍約為數 PF;順向偏壓時為擴散電容,範圍約為數μF 28. 原電路等效 mA 4 100 6 . 0 1 ID= − = D D D I V P = × mW 4 . 2 6 . 0 4× = =99-2 電機與電子群 專業科目(一) 共3 頁 第 3 頁 29. ≡ 1 D off,D2 ON ∴ 2.45V 5 . 8 1 5 . 1 1 8.5 5 5 . 1 2 Vo = + + = 30. 二次側峰值 22 2V 5 2 110 V2m = = (半波) 2 1 2 ) 6 . 0 V ( V(av)= π2m − × + V 2 . 6 3 2 ) 6 . 0 2 22 ( − × = π = 31. 11 2 V 10 2 110 V2m= = , V 2 2 11 V 2 1 ' V2m= 2m= V 65 . 1 3 1 2 11 10 5 5 ' V 2 VA=π 2m× + = π × = 32. ○1 Vi>0(正半週) ON D V 6 3 . 3 2 . 2 3 . 3 10 Vo= × + = ⇒ ,∴Vo(max)=+5.5V ○2 Vi<0(負半週)⇒Doff V 6 3 . 3 2 . 2 3 . 3 10 Vo(min)=− × + =− ○3 ΔVo=Vo(max)−Vo(min)=5.5−(−6)=11.5V 33. Vo=−4~+16V 34. IC=βIB+(1+β)ICBO, 99 99 . 0 1 99 . 0 1−α = − = α = β ∴IC =99×15+(1+99)×5μA=1985μA=1.985mA 37. 5 . 0 ) 100 1 ( 2 ) 2 ( 7 . 0 2 IB × + + − − − = ≒0.063 mA mA 3 . 6 I 100 IC= × B= 2 3 . 6 ) 5 . 0 2 ( 18 VCE =− + + × − ≒−4.3V 38. 99I ) 20 7 . 0 I ( 2 12 VC= − × B+ + B 7 . 0 ) 20 7 . 0 I ( 100× B+ + = mA 0257 . 0 IB= ⇒ ∴VC≒6.8 V 39. ) 100 2 2 ( 2 16 VC= − × + E R ) 100 2 2 ( 7 . 0 ) 100 2 ( 250× + + + × = E E R R 02 . 2 7 . 5 96 . 11 = + ⇒ ⇒ ≒3.1 kΩ 40. (1) 有CE:Zi=90//10//3=2.25kΩ (2) 無CE:Zi=90//10//(3+101×1)≒8.3 kΩ 41. (A) 共基極(CB)具有極低輸入阻抗與極高輸出阻抗 42. 2mA 5 7 . 0 7 . 10 IE = − = , = = =12.5Ω mA 2 mV 25 I V r E T e e C V Rr A =+α⋅ ≒ 160 5 . 12 k 2 = ∴Vo(P−P) =AV×Vi(P−P) =0.32V 43. ) mW 1 P log( 10 40= ⋅ o − ∴ 10 P 10 W 0.1 W mW 1 P 7 o 4 o = − ⇒ = − = μ 44. 6 3 3 ) 1 ( ) 1 ( 800 I I A 1 2 i o i= = = +β × +β × + ∴β1=39,β2=59 45. ) 2 // 10 // 40 ( 4 . 0 ) 2 // 10 // 40 ( 2 6 // 3 V V V V V V A s b b o s o VS= = × =−β× × + 200 2 6 . 1 250× =− − = 46. ⎩ ⎨ ⎧ ≥ < ≤ > ) ( V V V V PDMOS ) ( V V V V NEMOS P GD P GS t GD t GS 夾止區 , : 夾止區 , : ⎩ ⎨ ⎧ < ≤ ≤ < ⇒ ) PDMOS ( V 5 . 5 V V 3 ) NEMOS ( V 5 . 6 V V 3 G G ∴VG=4.5V符合 47. (A) CSÆ反相 (B) CDÆ極高輸入阻抗,極低輸出阻抗 (C) CDÆ源極隨耦器 48. (B) CMOS:交換速度慢 49. I 8 k(2.5 0.5)2 k 2 D= = − ⇒ = mA/V2 mA 18 ) 5 . 0 5 . 3 ( 2 ID= × − 2 = 50. 2 GS 2 P GS DSS DQ 4) V 1 ( 12 3 ) V V 1 ( I I − − × = ⇒ − = ∴VGS=−2V 3 ) 4 2 1 ( 4 12 2 ) V V 1 ( V I 2 g P GS P DSS m − = − − × × = − × − = mA/V