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(elec101)[2011](s)quiz1~2286^_35348.pdf
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ELEC 101 (L1) Quiz 2A April19 7:10pm-7:50pm
Name: )'0 I'" f,~ \.'1 ID No. _
Chinese Name: _
Number Max Score Score Number Max Score Score
1 1 4 4
2 1
3 8 Total 14
Useful information: 109 B G 106 B M 103 B k . 10-3 B m 10-6 B Il 10-9B n 10-12B P
.()_C dvoCt) ()_ Ldiit)
Ie t ---ve t ---dt dt
Ve(t) =Ve(O) + [Ve(oo) -Vc(O)](1-e-th)
it (t) = it (0) + (itCoo) -it (0)](1-e-tl<)
This is a CLOSED book and CLOSED notes examination.
1. Find Cell ofFig. P-1. 1mark
Dl,
4013~Fy~~:
Fig. P-l
Lf:-1M II C 3M-+
"l.cA-11 ~AA-)
[Cli~ o. ~ p> /'\ f]
ELEC 101 (L1) Quiz 2A April19 7:10pm-7:50pm
2. Find Leq of Fig. P-2. 1 mark
i'r=-~h1.. /leIM...,. l--t.<-#'4c......) Fig. P-2 15::: ~ (" MH \ ~
I,'"
3. RC Circuit: refer to Fig. P-3. 8 marks
~ R=lk
Sl let) mol
r+
Vs=4V' + c= lJ.lF --,-Vc(t)
Vc(O)=2V
..
Fig. P-3
3a. What is the time constant of the RC circuit? 1 mark
-z =-C!~ X!,1A)
-
j?" /"'5J
ELEC 101 (L1) Quiz 2A April19 7:10pm-7:50pm
3b. The capacitor is initially charged to 2V. At t==O, the switch Sj 3 marks is turned on. Sketch the output voltage Vc(t) for 8ms after switching.
v, (0) :. 2
~t)
\41'{)= 2.-r[ If -J,J(1-e ;;;
l/c-cot') =-'f
_-t:.
'" tt-2 e' 7Z, V
'r.=-,~~
\k. (/.1) Vl--( ~ /Ir)) :: V-__ 'J,.. e --
1"'1
~ 3; qq q
7Iq{tLL-~--~
. ~:::--==-
1--
trWtf--.(S)
ZM
2 marks 3c.
,~
't -V~(~) ,,2 e IWI
txt) :
'1{ A.
-JI-rf '*
2 e -;;:;
Z! 1".) :: m,l.}
-f),67.M.A.
~~)
rCo):: "J..1h A
L~ (s)
~""
ELEC 101 (L1) Quiz 2A April19 7:10pm-7:50pm
3d. What is the initial energy stored in the capacitor in Fig. P-3 if it is 1 mark initially charged to 2V?
1-J,.
[ ,-..,C V
-,'M,1fI Itt--
-J (IAA) (,2) 2-
-
1-
' ". "2-M-
f J
-I" /f/II/,-:;'
1
3e. What is the energy gained by the capacitor in Fig. P-3 ifit is fully 1 mark charged by Vs = 4V? .
j c V lElrf'76f{ "2-
~ i (1M) LY-)'-
,;-:-
~ ~4i\.-J.
I;~ C1.,)... ;-g,AI\---:l M-
et''" ~ 6k-~
ELEC 101 (L1) Quiz 2A April19 7:10pm-7:50pm
4. RL Circuit: refer to Fig. p-4. 4 marks
i(t)
+ Vs(t) =@ L=l~H Scos(2nSOt) , -
"::"
Fig. P-4
4a. Assume the inductor is initially relaxed, find the current i(t). 2 marks
;\J~(tf): i Jvte);'f .::. L JCAaC7-tf 5'0 t) rH IA/'-
:=:-_ C; _ <;,"-1 ()/fi 5'0 t) Up\.) (7--7; ~~)
l:({) ~ S-O;'O ~ 5,h (H.> -t) (t .j"
4b. What is the energy stored in the inductor when t = 5ms? 2 marks .3
~(}",,) =-',_>0 ~~. r;" C, 1i ~? C.~ (11)]
3
:: ~ (;; ')( /0 A 1\
.J, -.4 .... "1-
E-=-2--0'--A-
i Ct-11') C: P "-". 3_)1.
71
1,; =-/2-6, 1 II
..... IF Additional Paper for Rough Work or Hand Out