Name: (please print) Signature: ECE 2300 -- Exam #1 October 11, 2014 Keep this exam closed until you are told to begin. 1. This exam is closed book, closed notes. You may use one 8.5 x 11 crib sheet, or its equivalent. 2. Show all work on these pages. Show all work necessary to complete the problem. A solution without the appropriate work shown will receive no credit. A solution that is not given in a reasonable order will lose credit. Clearly indicate your answer (for example by enclosing it in a box). 3. It is assumed that your work will begin on the same page as the problem statement. If you choose to begin your work on another page, you must indicate this on the page with the problem statement, with a clear indication of where the work can be found. If your work continues on to another page, indicate clearly where your work can be found. Failure to indicate this clearly will result in a loss of credit. 4. Show all units in solutions, intermediate results, and figures. Units in the exam will be included between square brackets. 5. Do not use red ink. Do not use red pencil. 6. You will have 90 minutes to work on this exam. 1. /30 2. /35 3. /35 Total = 100
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ECE 2300 Exam 1 October 11, 2014 Page 3 1. {30 Points} Use the figure given below to solve this problem. Show your steps in some clear fashion. You are strongly encouraged to redraw the diagram as needed to make your work more clear. a. Find the equivalent resistance of this circuit as seen by terminals A and B. b. Find the equivalent resistance of this circuit as seen by terminals A and C.
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ECE 2300 Exam 1 October 11, 2014 Page 5 2. {35 Points} A multi-range voltmeter, shown in Figure 1, is made up of two resistors, R 1 and R 2, and a 180[mV], 7[mA] full-scale meter. This meter has two scales for reading, one from zero to -50[V] and the other from zero to -125[V], both for voltages with respect to the common terminal. This multi-range voltmeter is connected to the circuit in Figure 2, connecting terminals a to a, b to b, and c to c. a. Find the reading on the -125[V] of the multi-range voltmeter with the circuit in Figure 2 connected. b. Find the voltage at the -125[V] terminal with respect to the common terminal with the circuit in Figure 2 connected. Figure 1 Figure 2
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ECE 2300 Exam 1 October 11, 2014 Page 7 3. {35 Points} Use the node-voltage method to write a complete set of equations that could be used to solve the circuit below. Do not attempt to simplify the circuit. Do not attempt to simplify or solve the equations.
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ECE 2300 Exam 1-October11, 2014-Page 3 1. {30 Points} Use the figure given below to solve this problem. Show your steps in some clear fashion. You are strongly encouraged to redraw the diagram as needed to make your work more clear. a. Find the equivalent resistance of this circuit as seen by terminals A and B. b. Find the equivalent resistance of this circuit as seen by terminals A and C. ll[q] c D 25[Q] 23[Q] 24[Q] ~ 5[Jl1 res;.stor- i".j ~ '-f [Jl.-3 f'e.s 1'.J f- O/' i'j d~ [ ftj res,} for i's J a_ fjl) r-esr'stor... I J of e., -c1y..c"", teo1.. - ref la.ce wtt-l-i w1"re Shol't--c1'rCv.1'l-eJ.. - r~,1~c(? w1'f-j, opet\ c'if'ci.t;t short-_ c_,y..c,. 11 t-ej... _ ~f /4 c.e s hoit-- c1 re... ' e""- -,,.,.,'-t'i operi c1'rc1.11't:. t d (i I w,'fj, <?'ft",,, c,-rc"',"f ep ftce I ~ [ft] J / 2 ~ [ ~1 = I 0 ' I 0 [ Jl] IS[ Jlj J/ lb[;tj:: 7.7'-I [J>.-J ';).o [JL]/I ;i1 [JLJ = JO. ';1'-/[ft] ta);t-~ tl,e.se S~""'fJ,"f,'ca b'o"'sj /et ta.s rejv--~w. Qie r1- xt f48"v
ECE 2300 Exam 1 - October 11, 2014 -Page 4 Room for extra work th IA t- J 9 [ Jl] 11 I 0. ~ '{[ft J = b. 'C:,[ ft] a (\cl + ~ c;.. t t ~ c. t p a v-c;. /I e I Co IV\ h;t"'\"'~'o'1 i's,'vj se.,;e.i w~th l.7y[.ji] ) Let v.s (,. bf, [ J2) + I. 7Y [fl)= } '-1. lf O(Sl] I 4[Jl] E B A ll[ji) F l~[jl] c /0. JO[JL] / 7 [,n_j / f 1 i. 'ID { Jt] = 7. 79[Jlj a) for p a v" t ~) ) Yl 0 t ",'vi j,' s l.o n ri e c tej. -fu C.so we ) J;jv.ol/~ I 3[JL] f'esijtor 7. 71 [ JL) +- II [ JL] = J ~- 7'1 [fl] J 1r.?Cf [ n.] /) 1'1 [Jt] :: 'i. OJ. [fl] 'b.o?.[fl] + 10. /o[jlj = lli. Jd.[51J] h) for p qrt b) r1oth;t'\j i'.j co~t/1-ecf,j.. to BJ SD we 1j no~ t ~ e I O. I o [.52-] 'f'f.;,.. J tor J?. 79 { Jl] -1- J 'f[.fl J =- ;). I. 7 7 [ft J a L 7 1 [.n J / J Q, c _n.j) -= 7. 3 1 fl, J J.?, ) [Jl) t- I~ [ft) ::::@o. 3 J [;t,j}
ECE 2300 Exam 1 - October 11, 2014 - Page 5 2. {35 Points} A multi-range voltmeter, shown in Figure 1, is made up of two resistors, R 1 and Rb and a 180[mV], 7[mA] full-scale meter. This meter has two scales for reading, one from zero to -50[V] and the other from zero to -125[V], both for voltages with respect to the common terminal. This multi-range voltmeter is connected to the circuit in Figure 2, connecting terminals a to a, b to b, and c to c. sec.le a. Find the reading on the -125[V] of the multi-range voltmeter with the circuit in Figure 2 connected. 'I' b. Find the voltage at the -125[V] terminal with respect to the common terminal with the circuit in Figure 2 connected. ------ a -125[V] --------------- c Figure 1 t '!, e s e. v o I tet ~ e Fi ure 2 polav-;t;esj pos;t>ve. ct.cv-~-e.,,-t;j.,..,;ji /o...; v.p t'1e pe.3e. R ~?s[v] I 7[(YIA] =- J 0. 7 I [Jc.fl] ::. 7. J lf [tnj N~.,tt CbYlr'IC"c.t1'nj ) we t"ej..rc..w.j!=';fj\.\re. I t-o Fl j la. V'-l. a. TA ~ }< e y l~s to Jce.~p c.11 connec:t\or"s co.,. r- e c f:
ECE 2300 Exam 1-October11, 2014-Page 6 Room for extra work +... UA Ve. -lds[vj ~ I O.? I [ k Jl.J ISO[vJ i"' j -SO[v] +- b ifa 7.1 '-I [Jc llj c 0 rtl,.,o,, c IO[~J\.j 3. 3[t:n] Ct J 3. 3[.l:.aj a.-,.t?. I 'I [ k.fl] c..re i., f «rc..11 e I, {d h7 ~[... A]. i DR). - S[ A1( 3.~[Jcn] \ - [ lm..,, ~ 3 _?.[kn.]+- 7.l'l[kit]} - /.576 ma] lm _ tlre"'jil'i~?['"'a] -Jd,S-[ v] So J b) We \,JG.,..t l!'a ;If\.f:h< cllc..j;-~,.,, ~b 0 ve.. We. /c,.ow U(s ::-l~,,j'f[lcftj ifs =-JI. z~[vj A.. J.. U-c. ::: l O [,... AJ Io. '"7 / [".JI. j.:: I 0 7. I [ V j VA =Ile +-Vii -=- Jo7.1[11J - 11.2>[11] ={crs. irs[v])
ECE 2300 Exam 1-October11, 2014-Page 7 3. {35 Points} Use the node-voltage method to write a complete set of equations that could be used to solve the circuit below. Do not attempt to simplify the circuit. Do not attempt to simplify or solve the equations. ' 19[V] 20[.Q] I 33[.Q] 16[V] 21[.Q] 13[S]vx ~ f / ~ ll'c. +/b[v) -1- ZO[JlJ (J; lj: IF. c + c +. Id. ( + A + IZ[s] u; = ').. 7[JtJ ~3f.fl] x J. 'l[flj o LT 13 - ifc. :: I o ())< ' lf'p _ l)e =- //[fl] l G. lf'e.: -If> f v]
ECE 2300 Exam 1-October11, 2014-Page 8 Room for extra work rlr) Uv + tf:. ( J, J[..n] \ ::. 0 ~ /\ E. 31[.Sl] + d.d[jl.j) -ix + _Q - J'!.[s] UX + ~ + t 't{s]!jo.= 0 ~ b[.rj J.S[ fl.]