HE1fa07solutions - ECE 110 Professors Brunet and Loui HOUR...

Info icon This preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
Image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 4
Image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 6
Image of page 7
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: ECE 110 - ' . September 17, 2007 Professors Brunet and Loui ' HOUR EXAMINATION #1 1) Write your: Last Name (use capital letters): 30g“ ll 0 N S First Name (use capital letters): - _ Signature: » 2) Write your name and section at the back of the test. DONOT TURN THIS PAGE UNTIL YOU ARE TOLD A. Write or print clearly. Answer each problem on the exam itself. If you need extra paper, there is an extra sheet at the end of thisexam. Clearly identify" the problem number on any additiOnal page‘s. ' ' B. In order to receive partial or full credit, you must show all your work, e. g., your solution process, the equation(s) that you use, the values of the variables used in the equation(s), etc. You must also include the unit of measurement in each answer. Students caught cheating on this exam will earn a grade of F for the entire course. Other penalties may include suspension and/or dismissal ' from the university. Problem 1 (20 points) Consider the circuit below. a (a) [2 pts.] Write a KCL equation for node a. r“ (b) [2 pts.] Write a KVL equation that relates V1 and V2. V \ 2 \' 7. + Cl (c) [4 pts.] Use Ohm’s Law to write equations that relate the currents I 1 and 12 to the voltages V1 and V2. \J\ 3' 51‘ (d) [8 pts.] Determine the voltage V2 and the currents I 1 and I2 and I3. : \I 325 Km. \I c, . W, I: \I /§2 G/S-zl 2A 1': \I [2 = - [.524 1:43-: - — —m 31.4% °~ m =m (e) [4 pts.] Is the 4 A current source a load or source of power? Ex lain our reasonin . In SR8, tag. \I Masada. Cwnuft we: £4 ‘40", 4031; SR3 (A -(a x4=~gzl+w. 52cm W%Wuflm)fiwz¢wu Problem 2 (20 points) A periodic voltage is applied to a DC motor whose efficiency is 78%. Shown below are the graphs of motor voltage Vm and current 1",. I". (amPS) '0 I 21 31 51 61 _L_ ‘ F“ “3: goms=30xw’3.s (a) [6 pts.] Determine the period and frequency of Vm. Period = Frequency = 33 . .73 “Z (bzlf6pts'1 Determine the RMS voltage Vrm . 8‘ x20 + Gal-(”MO V‘“ Av (‘13 '= 30 27533 ‘3\ (a 94‘ \Ivms : '75. 33 ) o 10 30 M“ w— (c) [8 pts. ] Determine the time— a—veraged electrical power consumed by the motor. Show your work. , a (w a, v, I 3 ”Wk“, M3263“:— ~36,“ (9.3M 33-80“! finaCmS) > 7» ‘Slavd Paver= 3.? w Problem 3 (20 points) The three identical dashboard lights in a car are controlled by a dimer. We model the car battery by a 12 V ideal voltage source, the dashboard lights by three identical resistors in parallel, and the dimer by a variable resistor R1. Suppose the equivalent resistance of the three dashboard lights is R; = 15 Q. dimmer """""""""""""""""""""" dashboard lights Rd=15 Q - (a) [5 pts.] Determine the value of R2. PW rwfom “a“ “1 ‘1‘ “1 =- ”I I” R::(5x3‘: '45-“— I) my» (b) [6 pts. ] Using the Voltage Divider Rule, show that R1: 153—9 — 15. R‘ d lgx W- 343 V912) Vat: 12R: 1J7. :: ”2+6“ W 9 K. ‘ R" ‘ So (R +6)de (erz :\80 ‘ (8‘0 _‘g- Rug: lgO/Vd , and 2.: ”at (c) [9 pts.] Using (b), determine the value of R1 for which the total power Pd consumed by the dashboard lights is 0.4 W. Show your work. Th [9W P4=VaIJ=V4(Va/m\=\/}/RJ =O.4 W Wat VE=O~4W31g.,W \ld-‘i O.4$l§':fi w g8 FW£(b), R 23422—492: 1:9. ~(S-__ ".S—g S—{L =— Problem 4 (15 points) 1. 1) 3Q IZVG 29 A value of R was given to Sam Genius, who solved the circuit and found that the SRS power supplied by the voltage source is (—60 W). ' (a) [9 pts.] Find the current 1,, and voltage V1, and the SRS power p1 = V1 x 1,. Since, {M 5115 (2‘10: ~60, mwmd’ Io =-§fi, M I: - Io = 57*. “Men. \I; 1: x 7:- ...stz — «le Vt; V‘XI‘: (55;:- VSW (b) [6 pts.] Something does not seem to make sense. Sam must have made a mistake. Explain what does not make sense in two sentences (provide a clear, detailed argument). In ’Olu. 3.9.— (Mfof "ISW 04.42 diléipmd and sz LA Jiuim‘fifid Wm 0'60! I’m/(3'66 fi‘lfin ijwwg‘ WW raJJJ-CZJK 6 mVleageyaa—w «9.3 60W. (MSW MM 6;; Wm! 1.391111% QUESILQIS ["0 Points} What is the maximum power possible that can be supplied by the voltage source (in magnitude) for any possible value of R? For‘fim’di/m resident», Via. a NM (Manes: {A Problem 5 (10 points) The component C below has the I—V characteristic shown; the units are amps and volts. C V I=0.4V~—7.2 (a) [5 pts.] Determine the current Im measured (b) [5 pts.] Determine the voltage Vm measured by the ideal ammeter below. Explain your by the ideal voltmeter below. Explain reasoning. your reasoning. I. C‘ a *— c v a y»: b Problem 6 (15 points) Answer the following questions (check one choice for each). net (a) [2 pts.] The direction of a positive current indicates the direction of the glow of the electrons. 0 Always True UAIways False 0 It depends (b) [3 pts.] An ideal voltage source generates energy. 0 Always True 0 Always False Mt depends (c) [2 pts.] A resistor dissipates energy. Q/Always True 0 Always False 0 It depends (d) [3 pts.] KVL can be used on any circuit (with any circuit elements). ®/Always True 0 Always False 0 It depends (e) [2 pts.] The IV graph for a resistor is linear. Q/Always True 0 Always False Q It depends (f) [3 pts.] The RMS value of a signal is the peak value multiplied by «5 / 2 . 0 Always True 0 Always False (B/It depends ...
View Full Document

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern