天津商业大学07-08学年第1学期电路期末考试题(期末).pdf

1 2007 2008 学年第一学期 信息工程学院信息工程学院 电路电路 课程 试卷 课程 试卷 A 请考生注意 本试卷共 4 页 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 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 US IS 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 US R IS 2 2 scores The input resistance R of the following circuit is A 3 40 B 7 C 1 7 D 40 3 Answer 2S3S4S 12S R 3 3 scores the circuit is shown in the Fig Find the voltage between terminals a b then Uab is A 80 V B 0 V C 80 V D 50 V Answer a b 200V 200V 100V 50V 40k 20k 5k 60k 5 4 4 scores The parameters of the Norton equivalent circuit seen from terminals a b are as 2 4 1 A4 V6 3 A2 a b a b sc I o R 2 A1 o SC R I A 6 A1 o SC R I B 2 A7 o SC R I C 2 A1 o SC R I D 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 2 t seconds Then the time constant 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 US 10V I 2A when US 20V 6 IA If we let US 20V then the value of I is US I R N A 6 A B 10 A C 8 A D 8 A Answer 题 目 总 分 得 分 阅 卷 scores signature 装 订 线 班 级 姓 名 学 号 2 Fill the blank with the correct answer 6 problems 25 scores 1 4 scores Refer to the circuit as shown in the Fig When R 2 the power supplied by the dependent source is P W If the power absorbed by the dependent source is 4 W the value of the resistance R should be 12V2I 4V R 1 I 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 1 2 34 5 6 3 3 scores Assuming that the zero input response of a first order circuit is uCx t 5 3 eV and the zero state response is uCx t 21 3 Ve When the value of the excited voltage source is changed to three times as the original value the complete response will be ut C 4 4 scores For the circuit calculate the parameters of the Thevenin equivalent circuit The two parameters are OC U V 0 R 7V 1A 1 2A 3V 10I U 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 iL for t 0 2 Determine the initial conditions 2 6V iL 2H 2Ft 0 6 6 scores For the circuit as shown in the Fig The switch has been in position a for a long time At 0 t it switched to position b The complete response of ut C for t 0 is The steady state response is The transient response is The zero input response is The zero state response is 5V 1 001 F 2 10V t 0 uC scores signature a b 3 Fundamental calculation problems 4 problems 27 scores 1 7 scores for the circuit as shown in the Fig Using KCL and KVL find the currentI the voltage U and the power absorbed by the element X respectively X 4 1 2A 4A 6V 2 3 4A I U 2 6 scores Use equivalent transformation to simplify the following circuit Known that 4 L R calculate the current IL IL RL 2A 2 2 4 4 8V 8V 2A 3 7 scores For the circuit as shown in the Fig use mesh loop analysis to find the branch currents I1 andI2 1 2A 1V 1 1 1 1 I1 I2 4 7 scores Use nodal analysis to calculate x U and x I of the following circuit 1 2 3 V6 1 2 4 4 x U3 x U V2 x I scores signature 4 comprehensive calculation problems 3 problems 29 scores 1 9 scores Use superposition theorem to calculate the power supplied by the dependent source U2 2 U 1 4 V2 A1 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 U 1 U 4 4 4 4 R