EE302 - Exam__1_Review_solution

# EE302 - Exam__1_Review_solution - Exam #1 Prep Questions 1....

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Unformatted text preview: Exam #1 Prep Questions 1. KVL and KCL Problems A. B. For the circuit shown i. For both switches open, what are VA and V3? ii. For both switches closed, what are VA and VB? iii. For switch A open, and switch B closed, what are VA and V3? iv. For switch B open and switch A closed, what are VA and V ? Calculate vx and ix in. the circuit below. 19 + 2A 0 O vx Exam #1 Prep Questions C. Using the labels shown below, calculate IX and Vx. D. The circuit below consists of light bulbs A and B, switches I and II, an ideal voltage source V1 , and a variable resistor R1. R1 a) Answer the following questions, using these possible responses: 1) Both light bulbs are off 2) Light bulb A is on, light bulb B is off 3) Light bulb A is off, light bulb B is 4) Both light bulbs are on and light bulb A on is brighter 5) Both light bulbs are on and light 6) Both light bulbs are on and they have bulb B is brighter the same intensity A Both switches are open _LL Switch 1 is closed, switch 11 is open JL Switch 1 is open, switch 11 is closed _f,_ Both switches are closed (33 Exam #1 Prep Questions E. Calculate the power associated with each element in the circuit below. Be certain to clearly state whether each element is absorbing or delivering power. Exam #1 Prep Questions 2. Resistors in Series and Parallel A. Determine which elements in the circuit below are in series and which elements are in parallel sews: (5am), (q“’~’;|ll3) Pasta; m,i),c..s),(2,q), “(gym (M) bales same 5 B. The circuit below has four identical light bulbs connected to an ideal battery. Exam #1 Prep Questions (i) How do the brightness of these bulbs compare? Assume brightness is directly related to power. A31), A and D brighter 'll‘a" (1)3} C173 (ii) Which light bulb(s) draws the least amount of current? Bic. (iii) What happens to the brightness of the remaining light bulbs when light bulb C is removed B iblorish'lct‘, A ClNi DGTL dimmur (iv) What happens to the brightness of the remaining light bulbs when light bulb D is removed. All liglﬁb 50 bad . Calculate the equivalent resistance for each of the following circuits. All values for resistors are in Ohms. 1k 1k 1k NR: = 5K9. i Rml —-> 1k (b 2k 1k a MI 15.0. |o_()_ I09. Exam #1 Prep Questions (Rab “- 20.0. 3. Current and Voltage Division Use voltage division and the circuit below to complete the table shown. A. Exam #1 Prep Questions B. Use current division and the circuit below to complete the table shown. C. Use voltage and/or division in order to solve for the unknowns in the circuit below using the reference direction provided. 200 R 0.1A — —> SQ 4.5V 12 £2 SQ Exam #1 Prep Questions D. Use voltage and/or division in order to solve for the unknowns in the circuit below using the reference direction provided. 109 I o n, 8 Q 209 = ‘0 A izo— '95 A E. For the circuit below, calculte ix, iv, and the power dissipated by the 3-9 resistor. 209 Exam #1 Prep Questions F. For the circuit shown below: R1 R4 A 0 R3 R7 B 0 R2 R6 (a) Calculate the expression for the e uivalent resistance seen from a~b. Rab -' R +92 + R3 ll 394+ R"; 4- Paula.) (b) Place a voltage source with voltage V at a—b, positive terminal up (Hint: re-draw the circuit). Use voltage division to write an expression for the voltage across resistor R5 in terms of V and ap ropriate r s'stor values. \1 = v (1?3 11 (94+ was“ i. , PSHPL- ws RI. +— + t 1+4- + .6.“ i. 94*,l=s+ \$35th (6) Place a current source Wﬁﬁ- current a a—bfposmve c rrent up (Hlnt: re—draw the circuit). Use current division to write an expression for the current ﬂowing through resistor R3 in terms of I and the appropriate resistor values I ( ’Rn-HQ + Rslle T95 ’- PsHap +R7+ Rsllab In the circuit below, find i1, the power dissipated in the 40 Q resistor, and the power delivered by the current source. G. @ Exam #1 Prep Questions General Problems A. B. Calculate l and V in the circuit below Calculate I and the power being delivered by the current source in the circuit below Exam #1 Prep Questions @ C. Use any method you wish in order to solve for the unknown(s) in each of the circuits below. 500 3 Q + [/3 ' 1 3A , 5009 1009 5.5 lkﬂ 2009 ' 200 eﬂw—‘Wt (a) R (b) a - \V5=t.32\l 5 ~ ﬂea ' zoo SV 2009 4009 15 mA ‘ (C) D. Calculate the change in power being delivered by the 5-V battery and the power being absorbed by the 400-9 resistor in the circuit below when the switch moves from the open position to the closed position. le 120.0 5V 0 5000 gmhlck Elﬁn smilcln closed. Pa, = 45.qu (95., = —4Q.ImVJ elven: 27%}JWJ P4009.“ 157p“, E. LE) Exam #1 Prep Questions Consider the circuit below 29 69 129 652 0 129 3) Calculate the power being generated by the current source if the 40-9 resistor is absorbing 10 mW of power. P _. ._ Q39“) b) Using the current source from part (a), calculate the new power being absorbed by the 40-0 resistor if the 5—9 resistor changes to 30-9. quﬂ : M“) In the circuit below, calculate values for v)( and V1. 3 Exam #1 Prep Questions G. Calculate the power being delivered by the dependent source in the circuit below H. Calculate the total power delivered and absorbed by each element in the circuit below. Clearly state whether each element is absorbing or delivering power. Power Delivered or Absorbed mg- Dependent _ we Dependent at. l surce V1/4 Exam #1 Prep Questions 4. Circuit Design A. A voltmeter is used to determine the voltage across R3. The voltmeter is modeled by an ideal voltmeter with a 97 k9 resistor in parallel. Let R1 = 10 k9, R2 = 40 k9, Rs = 100 k9, and Is = 90 mA. Find the percent difference in the voltage across R3 with and without the voltmeter in the circuit when: i) ii) iii) iv) R1 '5 0 R2 R3 A/o load 522.4 22441 R3 = 100 Q 5,!!va 5387’ -J% R3=1k§2 59,:av 553% - 1% R3 =10 kQ 54.2.sv 512.? — 3. 8% R3 :100 kQ jenny 2224 -38 ‘79 B. In class we talked about circuit models for voltmeters and ammeters. These two meters can be combined together to a wattmeter: a meter which directly measures the power ﬂowing through resistor R4 in the circuit below where R] = 10 k9, R2 = 120 kQ, and R3 =10 kQ. 200 V; In this problem you will put together a wattmcter from an ammetcr with an internal resistance of 10 Q and a voltage sources with an internal resistance of 100 k9. b) D. Exam #1 Prep Questions Show how you’d combine the ammeter and the voltmeter to measure the power absorbed by a resistor connected between two points, A & B. Make sure you include the internal resistance in your diagram. Provide a brief justiﬁcation for your configuration choice. In the circuit above, R4 can take on values between 1 kg and 50 k9. Calculate the maximum error you’d expect in the measurement of the power absorbed by R4 with this wattmeter. m“ Error = 73 '7, If you wished to measure R4 more accurately, what SINGLE change would you . . a 9 make to the wattmeter. Why. inamsﬁ V0 Hmebr [251,5 113 “(L In the circuit below, find R1 such that Vn = 10V. Find the power dissipated in R]. 1009 2R 0 1 R1 V0 : All of the resistors in the circuit below have the same value R. 21) Find the value of R such that the source provides LOW of power to the circuit. b) If all of the resistors are to have the same power rating, what is the minimum power rating required to avoid exceeding the maximum? Assume the power rating may change by 1/8W increments (cg. 1/8W, 1/4W, 3/8W, ete.). (Hint: identify the resistor that dissipates the most power and compute its power rating requirements.) R a) Q = IUDQ [9) mln Power ((14:11?) 5‘ 74M) ...
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## This note was uploaded on 06/19/2008 for the course EE 302 taught by Professor Mccann during the Fall '06 term at University of Texas at Austin.

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EE302 - Exam__1_Review_solution - Exam #1 Prep Questions 1....

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