天津商业大学07-08学年第1学期电路期末考试题(期末)
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4Ω
1Ω 2A
I2
I1 1Ω 4A
1Ω 2A 1Ω
4A
3Ω I
6V
2Ω
X
U
2. (6 scores) Use equivalent transformation to simplify the following circuit. Known that R L = 4Ω , calculate the current I L .
4Ω 4Ω
°
U1 4Ω 4Ω
U1
100 V
R 20 V
° -4-
3 Ω 40 1 C. Ω 7
A.
°
Answer ( ) 5、 (4 scores) Assume that the voltage of a first-order circuit decreases exponentially, the voltage is 15V at t = 0 , and is 6V at t = 2 seconds. Then the time constant τ of the circuit is A. 0.458s B. 2.18s C. 0.2s D. 0.1s Answer ( ) 6、 (4 scores) For the circuit shown below, N is a linear active network， when U S = 10 V I = 2 A； when U S = 20 V， I = 6 A；If we let U S = −20 V, then the value of I is
2A
4．(7 scores) Use nodal analysis to calculate U x and I x of the following circuit.
2Ω Ux
1 4Ω
4Ω
2 2V Ix
2Ω
2Ω
6V
1Ω 3U x 3
4Ω 8V
8V
IL RL
4Ω 2A
-3-
Ⅳ comprehensive calculation problems (3 problems, 29 scores)
4、(4 scores) The parameters of the Norton equivalent circuit seen from terminals a-b are as： a ° 6V 4Ω 1Ω
° a
2Ω
4A
3Ω
2A
I sc
Ro b
°
学 号 ：
° b
I = −1 A A. SC Ro = 2 Ω
1Ω
+ 3V -
U
-
Ω, 1Ω R 4V 2I
5、(6 scores) the circuit has been in steady state before t = 0 − . The switch is opened at t = 0 . (1) Write the differential equation in terms of i L for t > 0 . (2) Determine the initial conditions.
I = −1 A B. SC Ro = 6 Ω
I = 7 A C. SC Ro = 2 Ω
I = 1 A D. SC Ro = 2 Ω
US
R
IS
2、(2 scores) The input resistance R of the following circuit is
I
B. 7 Ω
40 D. Ω 3
12S
Answer (
)
US
N
R
R
°
3S
4S
2S
A. -6 A B. -10 A
C. 8 A
D. -8 A
Answer (
)
-1-
Ⅱ. Fill the blank with the correct answer. (6 problems, 25 scores) 1、(4 scores)
3. (10 scores) scores signature The circuit as shown in Fig.(a), the waveform of the current source iS (t ) is as shown in Fig.(b). known that i L (0) = 2A . Find the response of u(t ) for t > 0 .
1．( 9 scores) Use superposition theorem to calculate the power supplied by the dependent source.
2Ω 2U 1Ω U 4Ω 2V 1A
u 2
iS A iL 2 1
iS 4Ω
u
4H
Ｏ
2
t s
2. (10 scores ) For the circuit, find (1) the value of R that will absorb maximum power from the circuit. (2) the value of the maximum power.
1 3 4
2Ω i L 6V
2H t=0
° °
2F
5
6、(6 scores) For the circuit as shown in the Fig. The switch has been in position a for a long time. At t = 0 , it switched to position b. The complete response of uC (t ) for t>0 is____________________________
1Ω
1V 1Ω
1．(7 scores) for the circuit as shown in the Fig. Using KCL and KVL, find the current I , the voltage U , and the power absorbed by the element X respectively.
2007-2008 学年第一学期
3、(3 scores) the circuit is shown in the Fig.. Find the voltage between terminals a-b. then U ab is A. 80 V
+200V
°
信息工程学院《电路》 （课程）试卷 A
— — — 班— 级 ： 装 订 线 — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — （请考生注意：本试卷共 4 页）
I 12 V
2、(2 scores) The graph G of a circuit as shown in the Fig.， the number of the tree branches is ______; the number of the independent loops is _______。
+ 5V _
1Ω
a
°
°
b 2Ω
_
10 V
0.01F
+ u _C
+
-2-
Ⅲ. Fundamental calculation problems (4 problems, 27 scores)
scoresLeabharlann Baidu
signature 3．( 7 scores) For the circuit as shown in the Fig. use mesh (loop) analysis to find the branch currents I 1 and I 2 .
B. 0 V
C. -80 V
°
D. -50 V
Answer (
)
+200V
试卷来源：题库 送卷人:王光艳 打印：李海丰 乔凤云 校对：滕建辅 题 得 阅 目 分 卷
Ⅰ Ⅱ Ⅲ Ⅳ 总 分
40kΩ
5Ω
20kΩ
°a
b° 5kΩ
° -50V
60kΩ -100V°
姓 名 ：
Ⅰ. In the following problems, select the correct answer (only one is correct). (6 problems, 19 scores) 1、(2 scores) Refer to the circuit, assume that R 、 U S 、 I S are all greater than zero. Consider the power supplied or absorbed by each element: A. the resistor absorbs power, and the current and voltage sources supply power simultaneously. B. the resistor and the voltage source absorb power simultaneously, and only the current source supplies power. C. the resistor and the current source absorb power simultaneously, and only the voltage source supplies power. D. the resistor absorbs power, while the current source supplies power. Power absorbed or supplied by the voltage source can not be determined. Answer ( ) scores signature
2
6
The steady-state response is ___________
_______,
The transient response is _______________________, 3、(3 scores) Assuming that the zero-input response of a first-order circuit is uCx = 5e
scores
signature
-
7V
+ 2A 1A
°
10Ω
I
°+
Refer to the circuit as shown in the Fig. When R = 2 Ω , the power supplied by the dependent source is P= the resistance R should be W; If the power absorbed by the dependent source is 4 W, the value of
t − 3 − t 3
The zero-input response is___________________，
V ，and the zero-state
The zero-state response is _____________________.
t=0
response is uCx = 2 (1 − e )V . When the value of the excited voltage source is changed to three times as the original value, the complete response will be uC ' (t ) = _______________。 4、(4 scores) For the circuit, calculate the parameters of the Thevenin equivalent circuit. The two parameters are U OC = V， R0 = Ω。
1Ω 2A
I2
I1 1Ω 4A
1Ω 2A 1Ω
4A
3Ω I
6V
2Ω
X
U
2. (6 scores) Use equivalent transformation to simplify the following circuit. Known that R L = 4Ω , calculate the current I L .
4Ω 4Ω
°
U1 4Ω 4Ω
U1
100 V
R 20 V
° -4-
3 Ω 40 1 C. Ω 7
A.
°
Answer ( ) 5、 (4 scores) Assume that the voltage of a first-order circuit decreases exponentially, the voltage is 15V at t = 0 , and is 6V at t = 2 seconds. Then the time constant τ of the circuit is A. 0.458s B. 2.18s C. 0.2s D. 0.1s Answer ( ) 6、 (4 scores) For the circuit shown below, N is a linear active network， when U S = 10 V I = 2 A； when U S = 20 V， I = 6 A；If we let U S = −20 V, then the value of I is
2A
4．(7 scores) Use nodal analysis to calculate U x and I x of the following circuit.
2Ω Ux
1 4Ω
4Ω
2 2V Ix
2Ω
2Ω
6V
1Ω 3U x 3
4Ω 8V
8V
IL RL
4Ω 2A
-3-
Ⅳ comprehensive calculation problems (3 problems, 29 scores)
4、(4 scores) The parameters of the Norton equivalent circuit seen from terminals a-b are as： a ° 6V 4Ω 1Ω
° a
2Ω
4A
3Ω
2A
I sc
Ro b
°
学 号 ：
° b
I = −1 A A. SC Ro = 2 Ω
1Ω
+ 3V -
U
-
Ω, 1Ω R 4V 2I
5、(6 scores) the circuit has been in steady state before t = 0 − . The switch is opened at t = 0 . (1) Write the differential equation in terms of i L for t > 0 . (2) Determine the initial conditions.
I = −1 A B. SC Ro = 6 Ω
I = 7 A C. SC Ro = 2 Ω
I = 1 A D. SC Ro = 2 Ω
US
R
IS
2、(2 scores) The input resistance R of the following circuit is
I
B. 7 Ω
40 D. Ω 3
12S
Answer (
)
US
N
R
R
°
3S
4S
2S
A. -6 A B. -10 A
C. 8 A
D. -8 A
Answer (
)
-1-
Ⅱ. Fill the blank with the correct answer. (6 problems, 25 scores) 1、(4 scores)
3. (10 scores) scores signature The circuit as shown in Fig.(a), the waveform of the current source iS (t ) is as shown in Fig.(b). known that i L (0) = 2A . Find the response of u(t ) for t > 0 .
1．( 9 scores) Use superposition theorem to calculate the power supplied by the dependent source.
2Ω 2U 1Ω U 4Ω 2V 1A
u 2
iS A iL 2 1
iS 4Ω
u
4H
Ｏ
2
t s
2. (10 scores ) For the circuit, find (1) the value of R that will absorb maximum power from the circuit. (2) the value of the maximum power.
1 3 4
2Ω i L 6V
2H t=0
° °
2F
5
6、(6 scores) For the circuit as shown in the Fig. The switch has been in position a for a long time. At t = 0 , it switched to position b. The complete response of uC (t ) for t>0 is____________________________
1Ω
1V 1Ω
1．(7 scores) for the circuit as shown in the Fig. Using KCL and KVL, find the current I , the voltage U , and the power absorbed by the element X respectively.
2007-2008 学年第一学期
3、(3 scores) the circuit is shown in the Fig.. Find the voltage between terminals a-b. then U ab is A. 80 V
+200V
°
信息工程学院《电路》 （课程）试卷 A
— — — 班— 级 ： 装 订 线 — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — （请考生注意：本试卷共 4 页）
I 12 V
2、(2 scores) The graph G of a circuit as shown in the Fig.， the number of the tree branches is ______; the number of the independent loops is _______。
+ 5V _
1Ω
a
°
°
b 2Ω
_
10 V
0.01F
+ u _C
+
-2-
Ⅲ. Fundamental calculation problems (4 problems, 27 scores)
scoresLeabharlann Baidu
signature 3．( 7 scores) For the circuit as shown in the Fig. use mesh (loop) analysis to find the branch currents I 1 and I 2 .
B. 0 V
C. -80 V
°
D. -50 V
Answer (
)
+200V
试卷来源：题库 送卷人:王光艳 打印：李海丰 乔凤云 校对：滕建辅 题 得 阅 目 分 卷
Ⅰ Ⅱ Ⅲ Ⅳ 总 分
40kΩ
5Ω
20kΩ
°a
b° 5kΩ
° -50V
60kΩ -100V°
姓 名 ：
Ⅰ. In the following problems, select the correct answer (only one is correct). (6 problems, 19 scores) 1、(2 scores) Refer to the circuit, assume that R 、 U S 、 I S are all greater than zero. Consider the power supplied or absorbed by each element: A. the resistor absorbs power, and the current and voltage sources supply power simultaneously. B. the resistor and the voltage source absorb power simultaneously, and only the current source supplies power. C. the resistor and the current source absorb power simultaneously, and only the voltage source supplies power. D. the resistor absorbs power, while the current source supplies power. Power absorbed or supplied by the voltage source can not be determined. Answer ( ) scores signature
2
6
The steady-state response is ___________
_______,
The transient response is _______________________, 3、(3 scores) Assuming that the zero-input response of a first-order circuit is uCx = 5e
scores
signature
-
7V
+ 2A 1A
°
10Ω
I
°+
Refer to the circuit as shown in the Fig. When R = 2 Ω , the power supplied by the dependent source is P= the resistance R should be W; If the power absorbed by the dependent source is 4 W, the value of
t − 3 − t 3
The zero-input response is___________________，
V ，and the zero-state
The zero-state response is _____________________.
t=0
response is uCx = 2 (1 − e )V . When the value of the excited voltage source is changed to three times as the original value, the complete response will be uC ' (t ) = _______________。 4、(4 scores) For the circuit, calculate the parameters of the Thevenin equivalent circuit. The two parameters are U OC = V， R0 = Ω。