EE-201, Review Probs Test 1 page-1 Spring 98 EE-201 Review Exam I Multiple Choice (5 points each, no partial credit.) 1. The voltage Vx in the circuit below is: (1) 3V (2) 2V (3) -2V (4) 1V (5) -1V (6) None of above 2. Consider the circuit below where each shaded box is a general circuit element. What is the current I? (1) 8A (2) 7A (3) -7A (4) 3A (5) -3A (6) None of above
EE-201, Review Probs Test 1 page-2 Spring 98 3. If I in = 7A, the current I out = (in amps): (1) 3 (2) 1 (3) 14/11 (4) 4 (5) 4/7 (6) None of above 4. This is a conceptual problem and requires no calculations for the answer. Consider the circuits below. All resistors are 1Ω except the one labeled RΩ. The difference between Req1 and Req2 is the presence of the RΩ resistor between points a and b. Circuit 1 Circuit 2 The equivalent resistances seen between the inputs of circuits 1 and 2, Req1 and Req2, respectively, satisfy (1) Req1 > Req2 for any R (2) Req1 < Req2 for any R (3) Req1 = Req2 for any R (4) There is no general relationship between Req1 and Req2. It depends on the value of R. (5) None of above
EE-201, Review Probs Test 1 page-3 Spring 98 5. In this problem, we model an operational amplifier as voltage controlled voltage source having a finite voltage gain A: Suppose an operational amplifier is connected in the so called voltage follower configuration below. The voltage across the terminals of the op-amp, V+ - V-, is: (a) V+ - V- = 0 (b) V+ - V- = A Vi (c) V+ - V- = Vi / A (d) V+ - V- = Vi / (1+A) (e) None of above
EE-201, Review Probs Test 1 page-4 Spring 98 6. For the circuit below, an appropriate nodal equation at the indicated supernode is: (a) 3Va +.5Vb = 11 (b) 3Va +.5Vb = 15 (c) 1.5Va +.5Vb = -11 (d) 1.5Va + 2Vb = 11 (e) none of above 7. Referring again to the circuit of problem 6, the node voltage Vb = (in volts): (1) 1 (2) 2 (3) 4 (4) 10 (5) 0 (6) none of these 8. In the circuit below, if v1(t) = 12V and i1(t) = 6A, then vout(t) = (in volts): (1) 40 (2) 22 (3) 16 (4) 6 (5) 4 (6) none of above
EE-201, Review Probs Test 1 page-5 Spring 98 9. The mesh equations for the circuit below are: 2-4 -0.5-1.5 6.5-2.5-0.5-2.5 3.5 i 1 i 2 = i 3 v 1 -v 2 0 Then R2 = (in Ω): (1) 0.5 (2) 2.5 (3) -4.5 (4) 1.5 (5) 6.5 (6) none of these 10. For the circuit below, the contribution to the output voltage by v1 = 26V with i1 = 0 is 8V. With v1 = 0 and i1 = 13A, the contribution to the output voltage is 9 volts. If v1 = 13 volts vout = (in volts): and i1 = 26A, then (1) 20.5 (2) 22 (3) 17 (4) 34 (5) none of these
EE-201, Review Probs Test 1 page-6 Spring 98 11. Find the current iy (in Amps), for the circuit shown below. (1) 5 (2) 1 (3) -2 (4) 10 (5) none of these 12. The linear network in the box in the circuit below contains at most resistors and linear dependent sources. Two separate dc measurements are taken from the circuit. In the first experiment it is found that when Vs = 7 Volts and I s = 3 Amps the load current is I load = 1 Amp. In the second experiment it is found that Vs = 9 Volts and I s = 1 Amp yields a load current of I load = 3 Amps. Find the load current, I load, (in Amps) when Vs = 5 Volts and I s = 10 Amps Hint: Either superposition or linearity must be used to solve this problem. You should obtain two equations in two unknowns (1) -4 (2) 3/4 (3) 9/11 (4) -1/2 (5) none of these
EE-201, Review Probs Test 1 page-7 Spring 98 13. The linear network in the box contains at most resistors and linear dependent sources. For an input voltage of Vs = 10 Volts the power supplied by the voltage source is found to be 20 Watts. If the source voltage is changed to Vs = 2 Volts, find the power supplied by the voltage source (in Watts). (1) 2/3 (2) 10 (3) 4/5 (4) 4 (5) none of these 14. For the network shown below, find the Thevenin equivalent resistance (in Ohms) seen looking into terminals a-b. (1) 15 (2) 5 (3) 20 (4) 10 (5) none of these 15. For the circuit of Problem 14, find the Thevenin equivalent voltage seen looking into terminals a-b. Recall that this is the open circuit voltage, vab, labeled in the circuit of Problem 14. The choices below are given in Volts. Hint: Consider mesh analysis or voltage division. (1) -2 (2) 30 (3) -15 (4) 5 (5) none of these
EE-201, Review Probs Test 1 page-8 Spring 98 16. The linear circuit below is found experimentally to have the voltage and current relationship shown. Which of the following circuits is its Norton equivalent? (1) (2) (3) (4) (5)
EE-201, Review Probs Test 1 page-9 Spring 98 17. The current i(t) is as shown in the graph below. The charge that is transported by the current i(t) through the surface S 0 of the conductor also illustrated below during the time interval, 0 t 3 seconds is (in Coulombs): (a) 7.5 (b) -7.5 (c) 15 (d) 10 (e) none of above 18. The maximum power that can be delivered to the load, R L, is (in watts): Hint: Consider source transformations. (a) 25 (b) 5 (c) 1.25 (d) 2.5 (e) none of above
EE-201, Review Probs Test 1 page-10 Spring 98 19. For the below circuit, the voltage drop V1= (in volts): (1) 6.4V (2) -6.4V (3) 3.2V (4) -2.6V (5) none of these 20. Again consider the circuit of problem 19. The voltage drop, V 2, across the independent current source in volts is: (1) 24.8V (2) 23.2V (3) 17V (4) 41.8V (5) none of these 21. Below is the graph of a circuit. All voltages are in volts and all currents are in amps. The value of the voltage, VBE, is (in V): (1) -29 (2) -21 (3) -13 (4) -4 (5) 17 (6) 29 (7) none of above
EE-201, Review Probs Test 1 page-11 Spring 98 22. Referring again to the circuit graph of problem 21, the current ix = (in A): (1) -4 (2) -3 (3) 0 (4) 4 (5) 6 (6) cannot be determined (7) none of above 23. The power absorbed by the resistor in the circuit below is 15 watts. The value of the resistor is R = (in Ω): (1) 2/3 (2) 1.5 (3) 2.582 (4) 6.667 (5) 10 (6) 15 (7) none of above 24. The value of R which makes Req = 6Ω is (in Ω): (1) 36 (2) 12 (3) 9 (4) 6Ω (5) 15 (6) 4 (7) none of above 25. Consider the circuit below. The voltage, vx = (in V): (1) 26 (2) 20 (3) 14 (4) 11.38 (5) 10 (6) 8 (7) none of above
EE-201, Review Probs Test 1 page-12 Spring 98 26. In the circuit below, V1 = 70V and V2 = 20V. The value of R1 necessary to achieve these voltages is (in Ω): (1) 140 (2) 100 (3) 50 (4) 42 (5) 40 (6) 20 (7) none of aobve 27. The value of I x in the circuit below is (in A): (1) 48 (2) 27 (3) 18 (4) 12 (5) 9 (6) 6 (7) 3 28. In the circuit below, the value of R (in Ω) for which I 1 = 2A is: (1) 85 (2) 50 (3) 35 (4) 2.08 (5) 100 (6) 213.6 (7) none of above
EE-201, Review Probs Test 1 page-13 Spring 98 29. The equivalent resistance, Req, seen by the current source, Is, equals (in Ω): (1) -0.6 (2) 9 (3) -9 (4) -3 (5) 3 (6) 1 (7) -1 30. The value of R for which the power delivered to the 10Ω resistor is 10 watts is (in Ω): (1) 2kΩ (2) 20kΩ (3) 500Ω (4) 50Ω (5) 200kΩ (6) 4kΩ (7) none of above
EE-201, Review Probs Test 1 page-14 Spring 98 31. If the input voltage Vs1 = 10V and the input voltage Vs2 = 5V, then Vout = (in V): (1) 20 (2) 15 (3) -10 (4) 5 (5) 0 (6) -15 (7) none of above 32. The input voltage, Vs = 10V. The output voltage, Vout = (in V): (1) 2/3 (2) 14 (3) 15 (4) -150 (5) 140 (6) -140 (7) 150
EE-201, Review Probs Test 1 page-15 Spring 98 Work Out Problem: (28 pts) Consider the circuit below: (i) (2 pts) Identify the apprpriate supernode. (ii) (16 pts) Write a set of nodal equations for the circuit (iii) (4 pts) Reduce the nodal equations to a set of two equations in the variables VA and VC only. (iv) (6 pts) Solve the nodal equations of part (iii) by any means you choose. You may use the trick formula a b c d -1 = 1 ad - bc d - b - c a if you want to. Specify VA, VB, and VC.
EE-201, Review Probs Test 1 page-16 Spring 98 MC: 1 (3) 2 (4) 3 (2) 4(1) 5(4) 6 (4) 7 (5) 8 (3) 9 (4) 10(2) 11 (1) 12 (1) 13 (3) 14 (4) 15 (1) 16 (2) 17 (1) 18 (3) 19 (4) 20 (4) 21 (2) 22 (5) 23 (4) 24 (6) 25 (3) 26 (2) 27 (7) 28 (1) 29 (4) 30 (1) 31 (5) 32 (7) WO: V_A =270 V, V_B = 180 V, V_C= 90 V