EE 201 Final Exam December 17 1997 General Instructions The exam is closed book closed notes Do not open the exam until you are told to begin Fill in your name student identification number and section number in the appropriate places on the computer scan forms Time 7 30 am 9 30 am 12 30 pm 3 30 pm Instructor DeCarlo Krogmeier Krogmeier Chen Section Number 0001 0002 0003 0004 The exam consists of 30 equally weighted multiple choice questions Please keep your computer scan sheets covered while you are working on the exam 1 Problem 1 For the circuit shown below Vs is 1 60 V 4 46 V 7 100 V 2 40 V 5 20 V 5 3 20 V 6 40 V 20 V 2A Vs 3 8A Problem 2 The circuit below contains a floating voltage source It is convenient to incorporate the supernode concept in setting up the nodal equation Pick the correct nodal equation involving the supernode 1 2V1 7V2 80 5 3V1 V2 10 3 3V1 V2 40 7 7V1 2V2 40 2 2V1 7V2 50 6 7V1 2V2 70 1 2 5V V1 2V 30 A reference node 2 V2 1 4 1 3 10 V 4 3V1 V2 40 Problem 3 Consider the circuit below with voltage sources Vs1 and Vs2 and mesh currents I1 and I2 Find the correct mesh equations for the circuit 6I1 4I2 Vs1 1 4I1 7I2 Vs2 2 6I1 3I2 Vs1 2I1 7I2 Vs2 3 6I1 4I2 Vs1 4I1 7I2 Vs2 4 6I1 3I2 Vs1 2I1 7I2 Vs2 5 4I1 9I2 Vs2 6 9I1 4I2 Vs1 4I1 9I2 Vs2 7 9I1 4I2 Vs1 6I1 4I2 Vs1 4I1 7I2 Vs2 2 3 4 Vs1 I2 I1 3 V s2 Problem 4 Compute Va for the circuit drawn below Answers in Volts 1 1 5 3 2 2 6 2 3 3 7 1 3 4 0 4 2V 1V 3V 1 2 Va 2 Problem 5 In the circuit below the current source is given by is t 2 5u t A Find iC 0 in Amps 1 1 4 4 7 7 2 2 5 5 3 3 6 6 iC t 15 is t 4 0 3 F Problem 6 Find the output Vo of the ideal operational amplifier below 1 1 V 4 4 V 7 7 V 2 2 V 5 5 V 3 3 V 6 6 V 2 k 1 k ideal 2V 2 k Vo 6V Problem 7 Find the differential equation for vC t 1 dvc t dt 2vC t vs t 0 5is t 2 dvc t dt 2vC t vs t 0 5is t 3 dvc t dt vC t vs t 0 5is t 4 dvc t dt vC t vs t 0 5is t 5 dvc t dt vC t vs t 0 5is t 6 dvc t dt 2vC t vs t 0 5is t 7 dvc t dt 2vC t vs t 0 5is t 0 5 vs t vC t 2F 5 i s t Problem 8 Choose the correct Norton equivalent circuit for the network shown below a 8 8 2V 2V 2A 4 b 1 2 5 A 2 a 4 1 5 A a 2 b 3 2A b 4 a 4 2 5 A a 2 b 5 2A b 6 a 20 2A b 7 1 5 A a 2 b a 8 b 6 Problem 9 In the circuit below a capacitor of value C7 0 is connected across terminals new A B The new equivalent capacitance Ceq satisfies new 1 Ceq Ceq new 4 Ceq C7 Ceq C7 Ceq 7 none of these new 2 Ceq Ceq new 5 Ceq C7 Ceq C3 new 3 Ceq Ceq new 6 Ceq Ceq C7 A C4 C2 C eq C1 B C5 C6 Problem 10 If vin t is given by the graph to the left of the circuit below the value of vout t at t 2 seconds assuming vC 0 0 is 1 1 V 5 4 V 2 2 V 6 2 V 3 3 V 7 8 V 4 4 V v t C v in t 0 1 mF 2 5 k 1 sec 2 sec ideal t v in t vout t 2 V 7 Problem 11 In the RC circuit below vout is 1 1 V 5 8 V 2 2 V 6 12 V 3 3 V 7 15 V 4 4 V ideal 7 5 1 u t V vout 0 1 F v C 2 5 Problem 12 The voltage Vx in the circuit below is of the form Vx AIs BVs Find A and B 1 A 2R B 0 25 4 A R B 0 25 7 A 0 5R B 0 25 2 A 0 5 B R 5 A 0 5R B 0 25 Is 2R R R Vx Vs 8 3 A 2R B 0 5 6 A 1 B 1 Problem 13 In the circuit below the switch has been closed for a long time when it is opened at t 0 For t 0 find the inductor voltage vL t in Volts 1 32 e 8t 3 24 4 16e 4t 7 none of these 2 32 e 8t 3 24 5 2e t 4 16 3 16e 4t 6 2e t 4 t 0 32 V 8 2H vL t Problem 14 Find the time constant of the circuit shown below 1 0 1 s 4 0 4 s 7 0 7 s 2 0 2 s 5 0 5 s 3 0 3 s 6 0 6 s v1 10 4 v1 0 01 F 9 Problem 15 The RL circuit shown on the left has the inductor current shown in the graph on the right The value of L is 1 0 08 H 5 0 30 H 2 0 10 H 6 0 60 H 3 0 15 H 7 0 03 H 4 0 20 H Response of Undriven RL Circuit 10 9 0 25 10 e Inductor Current in Amps 8 7 0 5 10 e 6 5 1 10 e 4 3 iL 50 2 2 L 1 10 e 0 0 75 1 5 1 2 3 Time in milli seconds 4 5 Problem 16 In the circuit shown below the source voltage is given by vs t 20 10u t V Find the current iL t for t 0 in Amps 1 7 5 2 5e 2t 4 5e 0 5t 7 6 2e 0 5t 2 7 5 2 5e 0 5t 5 5e 2t 3 3 3 e 2t 6 6 2e 2t 2 5 H i L t vs t 2 10 6 Problem 17 If vC 0 0 V find the value of R in Ohms which will produce vC 0 1 10 1 e 1 V 1 1 5 50 2 2 6 100 3 10 7 200 4 20 10 u t V 0 1 F R v t C Problem 18 For what range of values of R in Ohms is the circuit …
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